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The document presents a doctoral thesis on the roles of CYP2A6 gene polymorphism in nicotine dependence treatment. It discusses background topics like nicotine metabolism pathways, nicotine dependence assessment tools, and current treatment limitations. The study aims to evaluate how CYP2A6 gene variants and their interaction with CYP2B6*6 impact nicotine dependence treatment outcomes. Data was collected from 1862 participants and analyzed using logistic regression. Results found significant associations between CYP2A6 slow metabolizer variants and nicotine withdrawal/dependence symptoms on treatment outcomes.
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yawoakrodouoraldefensedraft101614r2pptnew-160213083313
- 1. Doctoral Thesis Presentation Title: Roles of CYP2A6 Gene Polymorphism in Treatment of Nicotine Dependence. Yawo Mawuli Akrodou October 2014 Walden University College of Health Sciences
- 2. Presentation Overview • Problem statement. • Study background. • Data collection, processing and analyses results. • Research questions and hypotheses. • Presentation of findings and their implications. • Study limitations, recommendations, and social implications. 2
- 3. Background: Problem Statement • General Problem: Lack of systematic nicotine dependence treatment. Classic nicotine therapies provide only temporary abstinence. More than 80% nicotine dependent treated relapse within a year (Foulds, 2006, p. 1). • Specific Problem: Difficulty to translate CYP2A6 gene variants nicotine metabolizers capability of metabolism into nicotine dependence treatment. Inconsistent information, interindividual variability, different genes frequencies, and study design issues (Kortmann et al., 2010). 3
- 4. Background: Tobacco Harm and Related Diseases • Association of tobacco’s chemicals with pulmonary cancers. 1950s Doll and Bradford study in United Kingdom (Medical Research Council [MRC], 2013). 1950s Hammond and Horn study in United States (Schneider, 2006). • Current high prevalence of nicotine and nicotine related diseases. The prevalence of nicotine is stalled at 20% 400 thousand deaths from nicotine-related diseases in US (CDC, 2011). 6 million people deaths from tobacco smoking (WHO, 2012). More than 26% of heart attacks, 12% to 19% of strokes attributable to smoking. http://galleryhip.com/nicotine-gum-cancer.html 4
- 5. Difference X-ray of smokers organs and Nonsmokers ones. • http://addictionblog.org/ 5
- 6. Background: Nicotine Metabolism Pathways • Nicotine: Powerful psychoactive chemicals or mood-altering drug. • Approximately 1.0-1.5mg of nicotine is absorbed in the lung with pKa = 0.8. • Transits by the blood-stream to the brain in 10 seconds. (Remington et al., 2010). • Biologically, 70%-80% of nicotine is catalyzed by the enzyme cytochrome P450 2A6 (CYP2A6). • Cotinine is completely transformed by CYP2A6 into trans-3-hydroxycotinine (Hukkanen et al, 2005). 6
- 7. Background: Nicotine Dependence • Nicotine Dependence: State of switching from regular smoking to permanent nicotine user. NB: Nicotine dependence is assessed using nicotine withdrawal syndrome scale nicotine dependence Syndrome scale. 7
- 8. Background: Nicotine Dependence Assessment Instruments • Fagerström Test of Nicotine Dependence (FTND; Piper et al., 2008). • Diagnostic and Statistical Manual [DSM-IV]) criteria (Mezzich, 2002). • Nicotine Dependence Syndrome Scale (NDSS; Shiffman, Waters, & Hickcox, 2004). • Wisconsin Inventory of Smoking Dependence Motives (WISDM; Piper et al., 2004). 8
- 9. Background: Nicotine Dependence Treatment Nicotine Dependence Pharmacotherapies • Nicotine replacement therapy (NRT). Patch, spray, gum, chewing gum, transdermal patches, nasal sprays, vapor inhalers, and sublingual tablets and lozenges. • Pharmacology (FDA approved drugs) Bupropion (Zyban®), and Varenicline (Champix ®) Cognitive behavioral therapy • Advising and motivational techniques. Hukkanen et al. (2005). 9
- 10. Background: Treatment Limitation Facts • More than 80% of nicotine dependents treated relapse within 6 months or 1 year • Stall of the decrease of the prevalence of nicotine dependence at 20% in USA. • 400 thousand nicotine dependence-related deaths a year. • More than $176 billion yearly nicotine-related disease treatments’ expenses labor and work loss hours. Center of Diseases Control and Protection (2011). 10 Oral Defense
- 11. Background: Lack of Personalized Treatment • Lack of effective and personalized treatment. • One size fits all paradigm. • Difficulty using genes information in treatment. Example of Nicotine Genes. DRD4: Reinforce nicotine dependence MA-O: Predispose to nicotine dependence CYP2A6: Dependence and Cessation CYP2B6: Cessation Ho et al.(2010). 11
- 12. Example of Nicotine Genes Table Example of Nicotine Genes 12
- 13. Background : Cytochrome P450 CYP 2A6 (CYP2A6) • CYP2A6 Polymorphisms Influences on nicotine metabolism Decrease nicotine metabolism. CY2A6*4A : Deleted , no function decrease. CYP2A*1H, *9A, &*12A: At least one loss-of-function allele. Normal Metabolizers CYP2A6*1A full function alleles. Increase nicotine metabolism. CPY2B6*6 : Nicotine dependence cessation. Mroziewicz & Tyndale (2010). Figure. CYP2A6 Molecular Location on chromosome 19: base pairs 40,843,537 to 40,850,446 http://ghr.nlm.nih.gov/gene/CYP2A6 13
- 14. Example of CYP2A6 Variants 14 Table Example of CYP2A6 Variants
- 15. Cytochrome P450 CYP 2B6 (CYP2B6) • Cytochrome P450 CYP2B6 (CYP2B6) CYP2B6 is known as a nicotine gene candidate that interacts with CYP2A6 and is responsible for bupropion metabolism and influence nicotine cessation. (National Center of Biotechnology Information [NCBI], 2012). 15
- 16. Background: Study Purpose Statement Quantitative Cross-sectional study design to evaluate variables correlation. Assess CYP2A6 variants impact on nicotine treatment. Assess the interaction of CYP2A6 gene variants, and CYP2B6*6 variant impact in nicotine treatment. 16
- 17. Study Research Questions 1 and 2 •Research Question 1:How do the associations between CYP2A6 slow nicotine metabolizer gene variants, nicotine dependence syndrome or nicotine withdrawal syndrome, and therapy type (bupropion or NRT) affect nicotine dependence treatment outcome? •Research Question 2: How do the associations between CYP2A6 normal nicotine metabolizer gene variants, nicotine dependence syndrome or nicotine withdrawal syndrome, and therapy type (bupropion or NRT) affect nicotine dependence treatment outcome? 17
- 18. Study Research Questions 2 and 3 • Research Question 3: How does an interaction between CYP2A6 slow nicotine metabolizer gene variants, gene variant CYP2B6*6, and therapy type affect nicotine dependence treatment outcome? • Research Question 4: How does an interaction between CYP2A6 normal nicotine metabolizer gene variants, gene variant CYP2B6*6, and therapy type (bupropion or NRT) affect nicotine dependence treatment outcome? 18
- 19. Study Hypotheses 1 and 2 19 Hypothesis 1 Ho: The associations between CYP2A6 slow nicotine metabolizer gene variants, nicotine dependence syndrome or nicotine withdrawal syndrome, and therapy type (bupropion, or NRT) do not have a significant impact on nicotine dependence treatment outcome. Ha: The associations between CYP2A6 slow nicotine metabolizer gene variants, nicotine dependence nicotine or nicotine withdrawal syndrome, and therapy type (bupropion or NRT) have a significant impact on nicotine dependence treatment outcome. Hypothesis 2 Ho: The associations between CYP2A6 normal nicotine metabolizer gene variants, nicotine dependence syndrome, or nicotine withdrawal syndrome and therapy type do not have a significant impact on nicotine dependence treatment outcome. Ha: The associations between CYP2A6 normal nicotine metabolizer gene variants, nicotine dependence syndrome or nicotine withdrawal syndrome and therapy type (bupropion or NRT) have a significant impact on nicotine dependence treatment outcome.
- 20. Hypotheses 3 and 4 Hypothesis 3 Ho: CYP2A6 slow metabolizer gene variants of nicotine interaction with gene variant CYP2B6*6 and therapy type do not have a significant impact on nicotine dependence treatment outcome. Ha: CYP2A6 slow metabolizer of nicotine gene variant interaction with gene variant CYP2B6*6 and therapy type have a significant impact on nicotine dependence treatment outcome. Hypothesis 4 Ho: CYP2A6 normal metabolizer of nicotine gene variants’ interaction with gene variant CYP2B6*6 and therapy type do not have a significant impact on nicotine dependence treatment outcome. Ha: CYP2A6 normal metabolizer of nicotine gene variants’ interaction with gene variant CYP2B6*6 and therapy type have a significant impact on nicotine dependence treatment outcome. 20
- 21. Theoretical Foundation Theoretical Foundation: Behavioral genetic theory developed in 1869 by Galton in United Kingdom. Theory Principle • Causal relationships between genes and behavior. • Gene-genes, and gene-environmental interactions influences. • Genes use in diseases treatments. 21
- 22. Factors Influencing Nicotine Behavior and Metabolism Rate 22 Note. Environmental and biological factors that influence nicotine behavior and modulate nicotine metabolism. Figure 1. Factors influencing nicotine behavior and metabolism rate
- 23. Theoretical Framework Theoretical Framework: Personalized treatment concept. • Genetic makeup of individuals contributes to the liability to nicotine, or drug addictions (Hall et al. 2002). • Two individuals are 99.9% identical. • Zero one point % difference in DNA constitutes the origin of profound variation, diverse behavior, and visible traits. • Treatment tailoring to patient genotype. • Medication selection to maximize successful treatment odds. 23
- 24. Schema illustrating personalized medicine concept and its difficulties 24 Note. Dash lines indicate difficulties achieving personalized medicine. Figure 2. Schema illustrating personalized medicine concept and its difficulties
- 25. Study Method/Design • The study used cross-sectional quantitative method research study. • Allow to exanimate the correlation of independent and dependent variables in a clinical setting (Checkwoay, Pearce, & Kriebel 2004) • Increase the study power to detect association and to find interactions between gene variants (Cordell, 2009). • Aim to characterize and substantiate gene-gene and gene-environmental interactions (Cordell, 2009). 25
- 26. Study Participants and Sample size Population: Participants were drawn from nicotine-dependent individuals seeking cessation treatment in Madison and Milwaukee, WI, USA. More than 9,000 adult smokers between the ages of 18 and 80 were sampled (NCBI, 2011) as participants for randomized clinical trials organized by UW-TTURC from 2001–2009. Approximately 2,575 individuals were enrolled in randomized clinical trials involving different medication treatments and have provided blood samples. The sample size consists of to 1,862 participants. This number is based on calculation using Quanto Version 1.2 genetic software for genes-genes and genes-environmental effect determination in clinical treatment. 26
- 27. Study Variables Dependent variable: Quitting Status (QS) Independent variables SM: Slow major nicotine metabolizer genes NM: Normal major nicotine metabolizers genes WS: Withdrawal syndrome Score low score 0-4 and high score is 5-10 on scales ND: Nicotine dependence score the same Th: Treatment type (NRT, Bupropion, and Placebo) • Covariate: Age, Education Attainment, Ethnicity/Race and Gender 27
- 28. Data Sources • Clinical Studies of Wisconsin Transdisciplinary Tobacco Use Research Center (UW-TTURC) from 2001–2009 in Madison and Milwaukee, WI, USA (NCBI, 2011). Approval and Permission • Walden University Internal Review Board approval. • National Health Institute permission. 28
- 29. Data Sources: Original Clinical Trial Studies Description 29 Table 7 Original Clinical Trial Studies Description
- 30. Data Collection Methods • Survey questionnaires • Alveolar carbon monoxide (CO) level testing to confirm level of CO in the blood. • Genotyping using 96 well plates using the Illumine HumanOmni2.5-4v1 D array. • Gene sampling and clustering using GenomeStudio version 2010.2 Genotyping Module version 1.7.4 and GenTrain version 1.0. Genotyping call rates for all SNPs were >> 98.71% Mean = 0.99, SD = 0.0071, max = 1.00, min = 0.85. National Center of Bioinformation (2011). 30
- 31. Data Analysis Methods • Descriptive statistic was used to process and to determine: sample composition, Percentage of dependence and withdrawal syndrome scores. • Beagle and Plink software were used to predict participants genotype. • Chi-square (χ2) test was used to verify genotype normal distribution in the population. • Logistic regression model was used to test hypotheses. 31
- 32. Data Processing Results 32 Original sample N = 1, 972 Missing dependence score = 6 Missing Withdrawal score = 28 Mismatched and genotypes = 51 Unknown = 55 Other races = 4 FTND: Dependence scores Mean = 4.92, SD = 1.31 WS: Withdrawal score Mean = 5.41, SD = 2.15 Final Sample N = 1862
- 33. Data Processing Results 33 Table Data Processing Results
- 34. Data Analysis Results: Sample Demographics The study Sample is composed by the most 1099(59.0%) participants of 31-50 of age. 262 (14.1%) African Americans. 1600 (85.59%) Caucasians. 802 (43.1%) Graduates. 772 (41.4%) Females. 1090 (58.6%) Males. 34
- 35. Study Sample Demographics 35 Table. Sample Demographics
- 36. Data Analysis Results : FTND and WS Scores FTND: Nicotine Dependence • Thirty-two point one percent (32.1%) of participants reported a low level of nicotine dependence, and 67.9% reported a high level of nicotine dependence. WS: Withdrawal Syndrome • Forty point eight percent (40.8%) of all participants reported experiencing nicotine withdrawal syndrome during treatment, and 59.2% reported craving. 36
- 37. Low and High Dependence Subgroups 37
- 38. Data Analysis Results : Genotype Distribution Frequency, Treatment Group, Quiting Status. Nicotine Genes Variant Carriers • Normal Metabolizer (NM): CYP2A6*1A: 69.1% • Slow Nicotine Metabolizers Carrier CYP2A6*4A: 56.5% CYP2A6*1H: 46.9% CYP2A*9: 38.2% CYP2A6*12A: 58.6% CYP2B6*6: 48.1% Treatment Group • Receive Nicotine replacement therapies (NRT): 45.1% Received bupropion: 35% Received placebo: 10.5% placebo. Quitting Status within 6 months Reported quitting: 29.4% Did not quit : 70.6% 38
- 39. Genotype distribution frequency in the whole population 39 Figure 4. Genotype distribution frequency in the whole population
- 40. Hypothesis 1: Test Result for Nicotine Syndrome Association Slow Metabolizers •Research Question 1: How do the associations between CYP2A6 slow nicotine metabolizer gene variants, with nicotine withdrawal syndrome or nicotine dependence syndrome, and therapy type (bupropion or NRT) affect nicotine dependence treatment outcome? Result: Significant impact with CYP2A6*1H (OR = 1.55, 95% CI [1.12-1.90] ; p < 0.001). CYP2A6*4A (OR = 1.60, 95% CI [ 1.13-1.95] ; p < 0.001). CYP2A6*9A (OR = 1.35, 95% CI [1.10-1.65] ; p < 0.001). CYP2A6*12A ( OR = 1.46, 95% CI[1.18-1.80] ; p < 0.001). Conclusion: Participants carrying one of these slow nicotine metabolizer gene variants were 1.35, 1.46, 1.55, or 1.60 times more likely to maintain abstinence 6 month posttreatment. 40
- 41. Hypothesis 1: Test Result for Withdrawal Syndrome Association with Slow Metabolizer Result : Significant impact with: CYP2A6*1H (OR = 1.54, 95% CI [1.26-1.89] ; p < 0.001). CYP2A6*4A, (OR = 1.59, CI [1.30-1.95] ; p < 0.001). CYP2A6*9A (OR = 1.45, CI[1.18-1.80]; p < 0.001). CYP2A6*12A( OR = 1.46, CI[0.10-1.65] ; p = 0.001). Conclusion: Participants carrying one of these slow nicotine metabolizer gene variants were 1.35, 1.45, 1.54, or 1.59 more likely to maintain abstinence 6 month posttreatment. 41
- 42. Hypothesis 2: Test Result for Nicotine and withdrawal Syndromes Association with Normal Metabolizers • Research Question 2: How do the associations between CYP2A6 normal nicotine metabolizer gene variants, nicotine dependence syndrome, or withdrawal dependence syndrome, and therapy type (bupropion or NRT) affect nicotine dependence treatment outcome? Result: Significant impact on nicotine dependence treatment outcome with CYP2A6*1A (OR = 1.35, 95% CI [1.11-1.70]; p < 0.003) for nicotine dependence syndrome. CYP2A6*1A (OR = 1.40, 95% CI [1.11-1.75]; p < 0.004). nicotine withdrawal syndrome. Conclusion: Participants carrying CYP2A6*1A were 1.35 times more likely to maintain abstinence 6 month posttreatment period, and were 1.40 times more likely to maintain abstinence 6 month posttreatment period for those who had experienced nicotine withdrawal syndrome during treatment. 42
- 43. Hypothesis 3: Test Result for Nicotine Syndrome Association with Slow Metabolizer • Research Question 3: How does an interaction between CYP2A6 slow nicotine metabolizer gene variants, gene variant CYP2B6*6, and therapy type affect nicotine dependence treatment outcome? Result : Significant impact on treatment outcomes with: CYP2A6*1H (OR = 1.56, 95% CI: [1.26-1.90] ; p < 0.001). CYP2A6*4A (OR = 1.61, 95% CI [ 1.31-1.96] ; p < 0.001). CYP2A6*9A (OR = 1.47, CI [1.18-1.88] ; p < 0.001). CYP2A6*12A (OR = 1.35, CI[ 1.11-6.7] ; p=0.004). Conclusion: Participant having one of these specific gene variants were 1.35, 1.47, 1.56 or 1.61 times more likely to maintain abstinence for s 6 month posttreatment period. 43
- 44. Hypothesis 3: Test Result for Withdrawal Syndrome Association with Slow Metabolizer Result : Significant impact for each slow nicotine metabolizer gene variant: CYP2A6*1H (OR = 1.57, 95% CI:[1.13-1.89] ; p < 0.001). CYP2A6*4A (OR = 1.70, 95% CI [01.15-1.95] ; p < 0.001). CYP2A6*9A (OR = 1.44, 95% CI [1.17-1.95] ; p < 0.001). CYP2A6*12A (OR = 1.32, 95% CI[1.10-1.64] ; p < 0.003). Conclusion: Participant having one of these specific slow nicotine metabolizer gene variants and gene variant CYP2B6*6 were 1.32, 1.44, 1.57, or 1.70 times more likely to maintain abstinence for six month posttreatment period. 44
- 45. Hypothesis 4: Test Result for Nicotine or Withdrawal Syndromes Association with NM • Research Question 4: How does an interaction between CYP2A6 normal nicotine metabolizer gene variants, gene variant CYP2B6*6, and therapy type (bupropion or NRT) affect nicotine dependence treatment outcome? Result 1: Significant impact on nicotine treatment outcome with: CYP2A6*1A (OR = 1.37, 95% CI [1.10-1.69]; p < 0.003) for nicotine dependence syndrome. Conclusion: Normal nicotine metabolizer CYP2A6*1A gene variant and CYP2B6*6 gene variant carriers were 1.37 times more likely to maintain abstinence for 6 month posttreatment period. Result 2: Significant impact on nicotine treatment outcome with: CYP2A6*1A (OR = 1.39, 95% CI [1.07-1.72] ; p < 0.004) nicotine withdrawal syndrome. Conclusion: Patients carrying normal nicotine metabolizer CYP2A6*1A gene variant and CYP2B6*6 gene variant were 1.39 times more likely to maintain abstinence for 6 month posttreatment period. 45
- 46. ANOVA (3x2) Genes Interaction Main Effect Testing for Hypotheses 3 and 4 • For hypothesis 3 slow nicotine metabolizers CYP2A6*4A and CYP2A6*12A interactions’ main effects with CYP2B6*6 were significant CYP2A6*4A, F (1, 50.2) = 134.49, partial η² = 0.068, p < 0.001, and CYP2A6*12, F (1, 34.9) = 132.38, partial η² = 0.059, p < 0.001. CYP2A6*4A and CYP2A6*12 tended to have a greater main effect with CYP2A6*6 in nicotine dependence treatment. • For Hypothesis 4, ANOVA result indicated a significant interaction main effect between normal nicotine metabolizer CYP26*1A and CYP2B6*6 gene variants, F (1, 38.2) = 127.72 partial η² = 0.065, p < 0.001 in nicotine dependence treatment. Both gene variants tended to generate a greater main effect on nicotine dependence treatment. 46
- 47. Findings and Previous Studies • How do findings related to the literature ? Nakajima et al. (2006) and Ho et al. (2010) case-control studies finding. Slow nicotine metabolizers carriers were 1.7 times more likely to quit smoking than noncarriers. • Epistasis consists of the interaction of many genes to express a specific phenotype or to play a specific function” (Russell, 2002). • Ring and Valdez (2007) finding.CYP2B6 interacted with CYP2A6 (p < 0.002 and 0.003) to clear nicotine from the organism. 47
- 48. Findings Related to Theoretical and Conceptual Framework. • How do findings relate to conceptual/theoretical framework? Gene-genes interaction impacts on nicotine treatment outcome. CYP2A6 and CYP2B6*6 interact to increase successful nicotine treatment. outcome as suggested by Ring and Valdez (2007) . Gene-gene environmental interaction . Education level, nicotine exposure to nicotine association impact nicotine treatments. 48
- 49. Example of Testing Among Different Subgroups • Example of Logistic regression analysis of the association of slow nicotine metabolizer gene variant CYP2A6*4A with nicotine dependence syndrome High odd ratios-61 to 80 years old (OR= 1.83, 95% CI[1.12-2.78], p = 0.002). Lower odd ratios 31-50 years old (OR = 1.57, 95% CI [1.20-2.02] ; p < 0.001). Lower female subjects ( OR = 1.27, 95% CI[ 0.93-1.75], p < 0.001) than for male subjects ( OR = 1.86, 95% CI[ 1.40-2.42] ; p < 0.001). Higher odds ratio for college graduates (OR = 1.30, 95% CI [0.10-1.63] ; p = 0.001) than for other educational background groups. Higher odds ratio for Caucasian descendants (OR = 1.63, 95% CI[ 0.93-2.0] ; p < 0.085) than for African American descendants (OR = 1.59, 95% CI [1.28-1.98] ; p = 0.001) . 49
- 50. Limitations • Correlational designed limitation. • Use of secondary datasets. • Environmental factor influence on genes. • Extreme variability of CYP2A6 and CYP2B6 gene variants and variability of genes frequencies (Khoury et al., 2010). • Limited subsets of ethnicities used (Caucasian and African American descendants). • Study design issues. 50
- 51. Recommendations for action • Replication of the current study in other populations with more diverse ethnicities. • Bigger sample sizes use. • Use of wide range of sets of alleles. • Pharmacogenomics: Assess the strength of medication used. • Use of cognitive variables. • Incorporate gene therapies in treatments. 51
- 52. Social Change Implications • Improve genetic profiling, gene screening, and gene testing results interpretations. • Better assessment of nicotine gene risk factors. • Advance individualized disease treatment. • Motivate population and parents gene screening. • Strengthen cognitive behavioral therapy. • Promote healthcare policy making. 52
- 53. Abstract – see notes section on components for abstract • Statement: Existing nicotine dependence therapies have decreased smoking prevalence in the United States, but the decline in the number of adult smokers is stalling, due, in part, to the limited efficacy of current therapies that lack treatment personalization. Cytochrome P450 2A6 (CYP2A6) gene variants are known to metabolize nicotine and possibly influence nicotine dependence treatment. These genes’ inconsistent information, interindividual variability, interactions with other genes, and environmental factors have made it difficult to use their information to improve nicotine dependence therapy. • Method and Design: This cross-sectional study based on behavioral genetic theory stating that environmental and genetic factors cause behavioral disorders, assessed the impact of slow nicotine metabolizers (CYP2A6*1H, CYP2A6*4A, CYP2A6*9, and CYP2A6*12A) and normal (fast) nicotine metabolizers (CYP2A6*1A) gene variants and their interactions with CYP2B*6 associated with nicotine therapy type and nicotine dependence and withdrawal syndromes on nicotine dependence outcome. • Results: CYP2A6*4A (OR = 1.60, CI [1.13-1.95]; p < 0.001) and CYP2A6*9A (OR = 1.47, CI[1.18-1.88] ; p < 0.001) were the most linked to the highest odds of successful treatment outcome, indicating that carriers of slow nicotine metabolizers were more likely to maintain abstinence 6 months post period treatment than normal (fast) metabolizer CYP2A6*1A (OR = 1.35, 95% CI[ 1.11-1.70] ; p < 0.003) carriers. • Social Implications: Study findings may be useful in gene counseling and nicotine gene therapy to tailor individualized nicotine clinical treatments, to increase smoking quit rates, and to induce positive social change by improving the lives of smokers and their families. 53
- 54. Thank you and questions • Chair: Dr. Peter Anderson • 2nd committee member: Dr. Sandra • URR: Dr. Roland Thorpe Questions? 54
Editor's Notes
- Slide 1: Title
- Slide 3: Presentation Overview. The overview consists of problem statement, study background, data collection and analyses results, research questions and hypotheses, findings and their implications. The study limitations, recommandations, and social implications, and at the end we have the listing of the abstract.
- Slide 4: Background- Problem Statement The Prevalence of nicotine dependence and related diseases and corresponding rates of mortality and morbidity are still high worldwide. Yet systematic nicotine dependence therapies that can provide a long-term cure have not been identified. Currently, there is not enough evidence to show that a specific nicotine therapy provides successful long-term abstinence. More than 80% nicotine dependent treated relapse within a year (Foulds, 2006, p. 1). Currently, the most studied and best known nicotine candidate genes are cytochrome P450 2A6 (CYP2A6) polymorphisms, which are the main nicotine metabolizing enzymes affecting nicotine pharmacokinetics and pharmacodynamics. These genes’ inconsistent information, interindividual variability, interactions with other genes, and environmental factors have made it difficult to use their information to improve nicotine dependence therapy.
- Slide 5: Background- Tobacco Harm and Related Diseases In the 1950s, Doll and Bradford found that the death rate from lung cancer among smokers was about 20 times higher than among nonsmokers in England (Medical Research Council [MRC], 2013). A similar study was conducted in the United States in the same period when epidemiologists Cuyler Hammond and Horn, who followed 188 thousand tobacco users over 3 years and 8 months, realized that most of the deaths in their study were related to lung cancer (Schneider, 2006). Since then, health institutes in England and the United States have placed nicotine cessation and treatment among their primary public heath priorities. According to the World Health Organization (WHO) more than 6 million people die each year from tobacco smoking (WHO, 2012). In the United States, the prevalence of smoking is 20%, and more than 26% of heart attacks, 12% to 19% of strokes, and 4 thousand deaths are attributable to smoking and nicotine-related diseases each year.
- Slide 6:Difference X-ray of smokers organs and Nonsmokers ones
- Slide 7: Background-Nicotine Metabolism Pathways Nicotine is powerful psychoactive chemicals or mood-altering drug, an alkaloid found in the nightshade family of plants (Solanaceae) that constitutes approximately 0.6%–3.0% of the dry weight of tobacco. According to Hukkanen et al. (2005), 1.0-1.5mg of nicotine is readily absorbed during smoking and passes through the lung alveoli membrane easily because nicotine is a weak base, with pKa = 0.8; the absorption of nicotine through the lung membrane is facilitated by pH level, then nicotine transits by the blood-stream to the brain within 10 seconds to induce pleasurable sensations in the brain. Biologically, 70%-80% of nicotine inhaled is turned into cotinine, and 90% of this reaction occurs under the influence of the enzyme cytochrome P450 2A6 (CYP2A6); the cotinine is then completely transformed by CYP2A6 into trans-3-hydroxycotinin.
- Slide-8: Nicotine Dependence Nicotine Dependence begings with an addiction to tobacco products caused by one of its main ingredients, the drug nicotine, which is a psychoactive or mood-altering drug with pleasurable, stimulant and depressive effects. These effects are temporarily pleasing, making people want to use it more and more, which leads people to switch from experimental smoking to regular nicotine use, and, finally, to nicotine dependence. Nicotine dependence and withdrawal syndromes scales are used to quantify patient nicotine dependence state.
- Slide 9: Background- Nicotine Dependence Assessment Instruments They are devices consist of a diagnostic scale used to provide a quantitative evaluation of the severity of tobacco dependence. The Fagerström Test for Nicotine Dependence (FTND). FTND has high test-retest reliability. It is an acceptable and a valid measure in terms of prediction of individual attempts to quit smoking or likelihood of relapse in smoking cessation, intervention and treatment Diagnostic and Statistical Manual IV (DSM-IV). Formal nicotine-diagnostic systems, such as the Diagnostic Statistical Manual-IV (DSM-IV) and the International Classification of Diseases-10 (ICD) evaluate different aspects of smoking behavior leading to nicotine dependence (Piper et al., 2008). Nicotine Dependence Syndrome Scale (NDSS) and the Wisconsin Inventory Smoking Dependence Motive (WISD-68). In addition, two comprehensive and multiple-dimensional nicotine-dependence scales, the Nicotine Dependence Syndrome Scale (NDSS) and the Wisconsin Inventory Smoking Dependence Motive (WISD-68), are evaluated using questionnaires about smoking behavior (Piper et al., 2008). These instruments help to determine the level of nicotine dependence in an individual. Silde 8: Background- Nicotine Dependence Treatments Nicotine Dependence Pharmacotherapies Nicotine-replacement therapy (NRT), Bupropion (Zyban®), Varenicline (Champix ®) are three types of drug-based aid used in smoking cessation that are approved by the Food and Drug Administration (FDA) in the US and by Health Canada (Kortmann, et al., 2010) and may be used in different forms. Nicotine-replacement therapy (NRT). NRT partially replaces nicotine to reduce cravings and withdrawal symptoms (Stead et al., 2008). NRT exists in various formulations, such as chewing gum, transdermal patches, nasal sprays, vapor inhalers, and sublingual tablets and lozenges. These NRT consist of buffered alkaline pH that increases the absorption of nicotine through cell membranes, mimicking the gradual rise of nicotine in the brain and blood levels, without reaching the sharp peaks observed in real smoking that leads to addiction liability (Hukkanen et al., 2005). Nevertheless, NRT provides only temporary relief in nicotine dependence treatment. Also, a meta-analysis of 132 trials result showed that the relative risk of abstinence for any form of NRT compared with placebo control was RR = 1.58, 95% CI [1.50; 1.66] (Stead et al., 2008). Bupropion Zyban®. Bupropion is commercially called Zyban® and was originally formulated as an atypical antidepressant. Since then, it has been effective in the treatment of nicotine dependence and depression (Hughes, Stead, & Lancaster, 2007). Specifically, it decreases cravings and treats nicotine dependence and withdrawal symptoms associated with smoking-related symptoms such as mood disturbances, difficulty concentrating and irritability (Durcan et al., 2002). The neurobiological mechanisms and processes by which bupropion aids smoking cessation are unclear (Kortmann et al., 2010). In comparison, bupropion relative risk for long-term abstinence (1.69) in nicotine dependence treatment is slightly higher than NRT (relative risk 1.66). In conclusion, both treatments provide temporary relief in nicotine dependence treatment. Varenicline Champix ®.Varenicline is also known as Champix ® and consists of a partial agonist for the α4β2 nAChRs (McNeil et al. 2010). Randomized and clinical trials have shown that varenicline provides relatively long-term abstinence rates after 6 months of treatment, approximately 26%, compared with 11% for placebo treatment (McNeil et al., 2010). This result shows that varenicline is slightly more effective nicotine medication than bupropion. Cognitive behavioral therapy (CBT) Cognitive behavioral therapy (CBT) consists of advising and motivational interventions that are usually combined with pharmacological therapy to treat nicotine dependence. CBT is designed to provide moral and material support, to help the nicotine-dependence high-risk populations to bypass social and economic pressure and to have self-efficacy to avoid nicotine in the first place, or to quit it at once (Ahluwalia et al., 2006). The combination of counseling and pharmacotherapy was more effective in nicotine treatment than pharmacotherapy alone with OR = 1.4, 95% CI [1.2-1.6] (Fiore et al., 2008; Hajek et al., 2009). CBT therapy also provides only temporary relief.
- Slide 10: Background- Nicotine Dependence Treatments Nicotine Dependence Pharmacotherapies Nicotine-replacement therapy (NRT), Bupropion (Zyban®), Varenicline (Champix ®) are three types of drug-based aid used in smoking cessation that are approved by the Food and Drug Administration (FDA) in the US and by Health Canada (Kortmann, et al., 2010) and may be used in different forms. Nicotine-replacement therapy (NRT). NRT partially replaces nicotine to reduce cravings and withdrawal symptoms (Stead et al., 2008). NRT exists in various formulations, such as chewing gum, transdermal patches, nasal sprays, vapor inhalers, and sublingual tablets and lozenges. These NRT consist of buffered alkaline pH that increases the absorption of nicotine through cell membranes, mimicking the gradual rise of nicotine in the brain and blood levels, without reaching the sharp peaks observed in real smoking that leads to addiction liability (Hukkanen et al., 2005). Nevertheless, NRT provides only temporary relief in nicotine dependence treatment. Also, a meta-analysis of 132 trials result showed that the relative risk of abstinence for any form of NRT compared with placebo control was RR = 1.58, 95% CI [1.50; 1.66] (Stead et al., 2008). Bupropion Zyban®. Bupropion is commercially called Zyban® and was originally formulated as an atypical antidepressant. Since then, it has been effective in the treatment of nicotine dependence and depression (Hughes, Stead, & Lancaster, 2007). Specifically, it decreases cravings and treats nicotine dependence and withdrawal symptoms associated with smoking-related symptoms such as mood disturbances, difficulty concentrating and irritability (Durcan et al., 2002). The neurobiological mechanisms and processes by which bupropion aids smoking cessation are unclear (Kortmann et al., 2010). In comparison, bupropion relative risk for long-term abstinence (1.69) in nicotine dependence treatment is slightly higher than NRT (relative risk 1.66). In conclusion, both treatments provide temporary relief in nicotine dependence treatment. Varenicline Champix ®.Varenicline is also known as Champix ® and consists of a partial agonist for the α4β2 nAChRs (McNeil et al. 2010). Randomized and clinical trials have shown that varenicline provides relatively long-term abstinence rates after 6 months of treatment, approximately 26%, compared with 11% for placebo treatment (McNeil et al., 2010). This result shows that varenicline is slightly more effective nicotine medication than bupropion. Cognitive behavioral therapy (CBT) Cognitive behavioral therapy (CBT) consists of advising and motivational interventions that are usually combined with pharmacological therapy to treat nicotine dependence. CBT is designed to provide moral and material support, to help the nicotine-dependence high-risk populations to bypass social and economic pressure and to have self-efficacy to avoid nicotine in the first place, or to quit it at once (Ahluwalia et al., 2006). The combination of counseling and pharmacotherapy was more effective in nicotine treatment than pharmacotherapy alone with OR = 1.4, 95% CI [1.2-1.6] (Fiore et al., 2008; Hajek et al., 2009). CBT therapy also provides only temporary relief
- Slide 11: Background -Treatment Limitation Facts Smoking cessation has major health benefits for men and women of all ages. However, a long-term cure for nicotine-dependence remains difficult to achieve since more than 80% of moderate-to-heavy smokers who seek treatment relapse within 1 year (Hughes et al., 2004). Comnnsequently there are 400 thousand death in United States and 6 million worlde wide. Beyond these, high mortality and morbidity rates, expenditure on treatment of smoking-related conditions, and productivity loss from premature deaths, illnesses, and disabilities cost more than $178 billion annually
- Slide 12: Background- Lack of Personalized Treatment Today, the search for novel and targeted nicotine dependence treatment is focused on treatment strategies that integrate relevant information regarding nicotine gene variants for use in diagnostics and prognostics and treatment, since classic nicotine dependence treatment programs (cognitive behavioral therapy, pharmacology therapy) are rooted in a “one size fits all” paradigm and cannot be readily tailored to the unique needs of patients based on their constellations of behavioral, biological, and clinical characteristics. Genes-genes and genes environmental interations complicate the personalized treatment.
- Slide-13: Example of Nicotine Genes
- Slide12: Background - Cytochrome P450 CYP 2A6 (CYP2A6) Currently, the research objectives of pharmacogenetics and pharmacogenomics are to translate the relevant functions of polymorphisms of CYP2A6 into clinical practices, as they variably convert nicotine to cotinine at 78%, which is further transformed into tran-3-hydroxycotinine (3HC; Ho & Tyndale, 2008). The evaluation of the enzymatic activities of CYP2A6 in in vitro and in vivo experiments has shown that CYP2A6 polymorphisms can alter or enhance the pharmacokinetics of nicotine, according to their structure (deleted/decreased or full function), thus confirming their propensity to predispose or protect individuals from nicotine dependence (Mroziewicz & Tyndale, 2010) and multiple experiment results show that some of CYP2A6 alleles encode for enzymes that have no function (e.g., CYP2A6*2, CYP2A6*4), others have reduced activity (e.g., CYP2A6*9, CYP2A6*12), and others have gene duplication alleles (CYP2A6*1x2A,*1x2B) that increase enzymatic activity.
- Slide 15: Example of CYP2A6 Variants
- Slide 16: Background- Cytochrome P450 CYP 2B6 (CYP2B6) The fact that CYP2B6 is found close to CYP2A6 suggests that they may interact in nicotine metabolism. Currently, there are findings that some of its variants are involved in nicotine drug metabolism, such as bupropion such as CYP2B6*6.
- Slide 17: Background-Study Purpose Statement The purpose of this cross-sectional study was to assess the impact of the associations of major CYP2A6 gene variants, nicotine dependence and withdrawal syndrome, CYP2B6*6 gene variant, and therapy type on nicotine dependence treatment outcome. The enzymatic activities of CYP2A6 genes are significantly associated with the metabolism of nicotine to cotinine, and they are capable of inhibiting or enhancing nicotine (Ho et al., 2010).
- Slide 18 : Study Research Questions 1 and 2. Research Question 1:How do the associations between CYP2A6 slow nicotine metabolizer gene variants, nicotine dependence syndrome or nicotine withdrawal syndrome, and therapy type (bupropion or NRT) affect nicotine dependence treatment outcome? Research Question 2: How do the associations between CYP2A6 normal nicotine metabolizer gene variants, nicotine dependence syndrome or nicotine withdrawal syndrome, and therapy type (bupropion or NRT) affect nicotine dependence treatment outcome?
- Slide 19: Study Research Questions 2 and 3. Research Question 3: How does an interaction between CYP2A6 slow nicotine metabolizer gene variants, gene variant CYP2B6*6, and therapy type affect nicotine dependence treatment outcome? Research Question 4: How does an interaction between CYP2A6 normal nicotine metabolizer gene variants, gene variant CYP2B6*6, and therapy type (bupropion or NRT) affect nicotine dependence treatment outcome?
- Slide 20: Hypotheses 1 and 2 Hypothesis 1 Ho: The associations between CYP2A6 slow nicotine metabolizer gene variants, nicotine dependence syndrome or nicotine withdrawal syndrome, and therapy type bupropion, or NRT) do not have a significant impact on nicotine dependence treatment outcome. Ha: The associations between CYP2A6 slow nicotine metabolizer gene variants, nicotine dependence nicotine or nicotine withdrawal syndrome, and therapy type (bupropion or NRT) have a significant impact on nicotine dependence treatment outcome. Hypothesis 2 Ho: The associations between CYP2A6 normal nicotine metabolizer gene variants, nicotine dependence syndrome, or nicotine withdrawal syndrome and therapy type do not have a significant impact on nicotine dependence treatment outcome. Ha: The associations between CYP2A6 normal nicotine metabolizer gene variants, nicotine dependence syndrome or nicotine withdrawal syndrome and therapy type (bupropion or NRT) have a significant impact on nicotine dependence treatment outcome.
- Slide 21.-Hypotheses 2 and 3 Hypothesis 3 Ho: CYP2A6 slow metabolizer gene variants of nicotine interaction with gene variant CYP2B6*6 and therapy type do not have a significant impact on nicotine dependence treatment outcome. Ha: CYP2A6 slow metabolizer of nicotine gene variant interaction with gene variant CYP2B6*6 and therapy type have a significant impact on nicotine dependence treatment outcome. Hypothesis 4 Ho: CYP2A6 normal metabolizer of nicotine gene variants’ interaction with gene variant CYP2B6*6 and therapy type do not have a significant impact on nicotine dependence treatment outcome. Ha: CYP2A6 normal metabolizer of nicotine gene variants’ interaction with gene variant CYP2B6*6 and therapy type have a significant impact on nicotine dependence treatment outcome.
- Slide 22: Theoretical Foundation The theoretical foundation of this study is rooted in behavioral genetic theory (BGT). BGT emphasizes the influence of the behavior of genes and their direct contact with environmental forces in the expression of a phenotype, as well as the relation between genes and disease development and treatment (Bassett, 2008).
- Slide 22: Factors Influencing Nicotine Behavior and Metabolism Rate
- Slide 24: Conceptual Framework The 0.1% difference in human DNA also dictates the individual’s susceptibility to disease, or the development of individual character. This slim difference in genotype not only serves as biometric identification, but also explains why we act differently or are differently susceptible to a disease treatment, defying successful individualized treatment.
- Slide 25: Schema illustrating personalized medicine concept and its difficulties
- Slide 26: Study Method/Design The study used cross-sectional quantitative method research study which allows to exanimate the correlation of independent and dependent variables in a clinical setting (Checkwoay, Pearce, & Kriebel 2004); and to increase the study power to detect association and to find interactions between gene variants (Cordell, 2009). This methodology is often used to characterize and substantiate gene-gene and gene-environmental interactions (Cordell, 2009).
- Slide 27: Study Participants and Sample size Population: Participants were drawn from nicotine-dependent individuals seeking cessation treatment in Madison and Milwaukee, WI, USA. More than 9,000 adult smokers between the ages of 18 and 80 were sampled (NCBI, 2011) as participants for randomized clinical trials organized by UW-TTURC from 2001–2009. Approximately 2,575 individuals were enrolled in randomized clinical trials involving different medication treatments. The sample size consists of to 1,862 participants. This number is based on calculation using Quanto Version 1.2 genetic software for genes-genes and genes-environmental effect determination in clinical treatment.
- Slide 28.-Study Variables Study variables consist of dependent variable: Quitting Status (QS), independent variables. SM: Slow major nicotine metabolizer genes, NM: Normal major nicotine metabolizers genes,WS: Withdrawal syndrome Score, ND: Nicotine dependence score and Th: Treatment type (NRT, Bupropion, and Placebo) and Covariate: Age, Education Attainment, Ethnicity/Race and Gender.
- Slide 29.-Data Sources Data used was provided by NIH after Walden unversity IRB aproval and NIH study approval. Data were collected from clinical studies of Wisconsin Transdisciplinary Tobacco Use Research Center (UW-TTURC) from 2001–2009 in Madison and Milwaukee, WI, USA (NCBI, 2011).
- 30-Data Sources: Original Clinical Trial Studies Description
- Slide 31.-Data Collection Methods Survey questionnaires, alveolar carbon monoxide (CO) level testing to confirm level of CO in the blood, genotyping using 96 well plates using the Illumine HumanOmni2.5-4v1 D array, gene sampling and clustering using GenomeStudio version 2010.2 Genotyping Module version 1.7.4 and GenTrain version 1.0. Genotyping call rates for all SNPs were &gt;&gt; 98.71% Mean = 0.99, dev. = 0.0071, max = 1.00, min = 0.85.
- Slide 32.-Data Analyses Methods Data methods consist of descriptive statistic used to process and to determine: sample composition, percentage of dependence and withdrawal syndrome scores. Beagle and Plink software were used to predict participants genotype. Chi-square (χ2) test was used to verify genotype normal distribution in the population. Logistic regression model was used to test hypotheses.
- Slide 33: Data Processing Results Original sample was N = 1972 and after excluding redundancy, missing data value and non-used participants the final sample was 1986. FTND: Dependence scores Mean = 4.92, SD = 1.31 and WS: Withdrawal score Mean = 5.41, SD = 2.15.
- Slide 34: Data Processing Results
- Slide 35: Data Analyses Results The study sample is composed by the most 1099(59.0%) participants of 31-50 of age, 262 (14.1%) African Americans, 1600 (85.59%) Caucasians, 802 (43.1%) Graduates, 772 (41.4%) Females and 1090 (58.6%) Males.
- Slide 36: Study Sample Demographics
- Slide 37: Data Analysis Results: FTND and WS Scores. FTND: Nicotine Dependence score: Thirty-two point one percent (32.1%) of participants reported a low level of nicotine dependence, and 67.9% reported a high level of nicotine dependence. WS: Withdrawal Syndrome Forty point eight percent (40.8%) of all participants reported experiencing nicotine withdrawal syndrome during treatment, and 59.2% reported craving.
- Slide 38: Low and High Dependence Subgroups
- Slide 39: Data Analysis Results: Data Analysis Results: Genotype Distribution Frequency, Treatment Group, Quiting Status. Based on multiple statistical analyses using BEAGLE utility “gprobs2linkage” software, 69.1% of all participants were identified as carriers of normal nicotine metabolizer gene variant CYP2A6*1A. For the slow nicotine metabolizer gene variant, of all participants, 46.9% were carriers of CYP2A6*1H, 56.5% were carriers of CYP2A6*4A, 38.2% were carriers of CYP2A*9, 58.6% were carriers of CYP2A12, and 48.1% were carriers of gene variant CYP2B6*6. For treatment groups, 45.1% of participants received nicotine replacement therapies (NRT), 35% received bupropion, and 10.5% received placebo. Of all participants, 29.4% reported quitting smoking, and 70.6% did not quit after 6 months of nondrug follow-up treatment.
- Slide 40: Genotype distribution frequency in the whole population
- Slide 41: Hypothesis 1: Test Result for Nicotine Syndrome Association Slow Metabolizers. After, adjusting for age, educational background, gender, and ethnicity, logistic regression analysis was significant for each CYP2A6*1H (OR = 1.56, 95% CI: [1.26-1.90] ; p &lt; 0.001), CYP2A6*4A (OR = 1.61, 95% CI [ 1.31-1.96] ; p &lt; 0.001), CYP2A6*9A (OR = 1.47, CI [1.18-1.88] ; p &lt; 0.001), and CYP2A6*12A (OR = 1.35, CI[ 1.11-6.7] ; p = 0.004) interaction with CYP2B6*6 gene variant associated with nicotine dependence syndrome and therapy type. Participants carrying one of these slow nicotine metabolizer gene variants were 1.35, 1.46, 1.55, or 1.60 times more likely to maintain abstinence 6 month posttreatment.
- Slide 42: Hypothesis 1: Test Result for Withdrawal Syndrome Association Slow Metabolizers After adjusting for age, education, ethnicity and gender in overall group of treatment, logistic regression results indicated that each slow nicotine metabolizer gene variants associated with nicotine withdrawal syndrome, and therapy type was significant, CYP2A6*1H (OR = 1.54, 95% CI [1.26-1.89] ; p &lt; 0.001); CYP2A6*4A, (OR = 1.59, CI[1.30-1.95] ; p &lt; 0.001), CYP2A6*9A (OR = 1.45, CI[1.18-1.80]; p &lt; 0.001) and CYP2A6*12A( OR = 1.46, CI[ 0.10-1.65] ; p = 0.001). Logistic regression results showed that participants carrying one of these slow nicotine metabolizer gene variants were 1.35, 1.45, 1.54, or 1.59 more likely to maintain abstinence 6 month posttreatment.
- Slide 43: Hypothesis 2: Test Result for Nicotine and Withdrawal Syndromes Association with Normal Metabolizers Syndrome logistic regression results indicated that normal nicotine metabolizer gene variant CYP2A6 *1A associated with nicotine dependence syndrome, and therapy type, had a significant impact on nicotine dependence treatment outcome CYP2A6*1A (OR = 1.35, 95% CI [1.11-1.70]; p &lt; 0.003) and nicotine withdrawal syndrome CYP2A6*1A (OR = 1.40, 95% CI [1.11-1.75]; p &lt; 0.004). This model predicted that participants carrying normal nicotine metabolizer gene variant CYP2A6 were 1.35 times more likely to maintain abstinence 6 month posttreatment period, and were 1.40 times more likely to maintain abstinence 6 month posttreatment period for those who had experienced nicotine withdrawal syndrome during treatment.
- Slide 44- Hypothesis 3: Test Result for Nicotine Syndrome Association with Slow Metabolizer Logistic regression analysis was performed to test this hypothesis. After, adjusting for age, educational background, gender, and ethnicity, logistic regression analysis was significant for each CYP2A6*1H (OR = 1.56, 95% CI: [1.26-1.90] ; p &lt; 0.001), CYP2A6*4A (OR = 1.61, 95% CI [ 1.31-1.96] ; p &lt; 0.001), CYP2A6*9A (OR = 1.47, CI [1.18-1.88] ; p &lt; 0.001), and CYP2A6*12A (OR = 1.35, CI[ 1.11-6.7] ; p = 0.004) interaction with CYP2B6*6 gene variant associated with nicotine dependence syndrome and therapy type. This model predicted that patients who carried one of these slow nicotine metabolizer gene variants and CYP2B6*6 gene variant were 1.35, 1.47, 1.56 or 1.61 times more likely to maintain abstinence for 6 month posttreatment period.
- Slide 45- Hypothesis 3: Test Result for Withdrawal Syndrome Association with Slow Metabolizer Also, after, adjusting for age, educational background, gender, and ethnicity, logistic regression analysis was significant for each slow nicotine metabolizer gene variant CYP2A6*1H (OR = 1.57, 95% CI:[1.13-1.89] ; p &lt; 0.001), CYP2A6*4A (OR = 1.70, 95% CI [01.15-1.95] ; p &lt; 0.001), CYP2A6*9A (OR = 1.44, 95% CI [1.17-1.95] ; p &lt; 0.001), and CYP2A6*12A (OR = 1.32, 95% CI[1.10-1.64] ; p &lt; 0.003) associated with CYP2B6*6 nicotine withdrawal syndrome, and therapies. This model predicted that patients who carried one of specific slow nicotine metabolizer gene variants and gene variant CYP2B6*6 were 1.32, 1.44, 1.57, or 1.70 times more likely to maintain abstinence for 6 month posttreatment period
- Slide 46 . – Hypothesis 4 : Test Result for Nicotine or Withdrawal Syndromes Association with Normal Metabolizer. After adjusting with age, education, ethnicity and gender, logistic regression analysis of the interaction of normal nicotine metabolizer gene variant CYP2A6*1A (OR = 1.37, 95% CI [1.10-1.69]; p &lt; 0.003) with CYP2B6*6 associated with nicotine dependence syndrome and therapy type had a significant impact on nicotine dependence treatment outcome. This model predicted that patients who carried normal nicotine metabolizer CYP2A6*1A gene variant and CYP2B6*6 gene variant were 1.37 times more likely to maintain abstinence for 6 month posttreatment period. Also, after adjusting for age, education, ethnicity and gender, logistic regression analysis for CYP2A6*1A (OR = 1.39, 95% CI [1.07-1.72] ; p &lt; 0.004) interaction with CYP2B6*6 gene variant associated with nicotine withdrawal syndrome and therapy type had a significant impact on nicotine dependence treatment outcome. This model predicted that patients who carried normal nicotine metabolizer CYP2A6*1A gene variant and CYP2B6*6 gene variant were 1.39 times more likely to maintain abstinence for 6 month posttreatment period
- Slide 47: ANOVA (3x2) Genes Interaction Main Effect Testing for Hypotheses 3 and 4 For hypothesis 3 slow nicotine metabolizers CYP2A6*4A and CYP2A6*12A interactions’ main effects with CYP2B6*6 were significant CYP2A6*4A, F (1, 50.2) = 134.49, partial η² = 0.068, p &lt; 0.001, and CYP2A6*12, F (1, 34.9) = 132.38, partial η² = 0.059, p &lt; 0.001. CYP2A6*4A and CYP2A6*12 tended to have a greater main effect with CYP2A6*6 in nicotine dependence treatment. For Hypothesis 4, ANOVA result indicated a significant interaction main effect between normal nicotine metabolizer CYP26*1A and CYP2B6*6 gene variants, F (1, 38.2) = 127.72 partial η² = 0.065, p &lt; 0.001 in nicotine dependence treatment. Both gene variants tended to generate a greater main effect on nicotine dependence treatment.
- Slide 48: Findings and Previous Studies Findings of this study were related to previous study. For examples : 1-Nakajima et al. (2006) and Ho et al. (2010) case-control studies finding. Slow nicotine metabolizers carriers were 1.7 times more likely to quit smoking than noncarriers as this study has found also. Epistasis consists of the interaction of many genes to express a specific phenotype or to play a specific function” (Russell, 2002). Ring and Valdez (2007) finding.CYP2B6 interacted with CYP2A6 (p &lt; 0.002 and 0.003) to clear nicotine from the organism.
- Slide 49: Findings Related to Theoretical and Conceptual Framework These theoritical consist of gene-genes interaction impacts on nicotine treatment outcome and has found that CYP2A6 and CYP2B6*6 interact to increase successful nicotine treatment. outcome as suggested by Ring and Valdez (2007) . and Also the study found that gene-environmental interaction . For example, education level, nicotine exposure to nicotine association impact nicotine treatments.
- Slide 50: Example of Testing Among Different Subgroups. Logistic regression analysis of the association of slow nicotine metabolizer gene variant CYP2A6*4A with nicotine dependence syndrome and therapy type indicated higher odds ratio for 61 to 80 year old subjects (OR= 1.83, 95% CI[1.12-2.78], p = 0.002) and lower odds ratio for subjects between 31-50 years old (OR = 1.57, 95% CI [1.20-2.02] ; p &lt; 0.001), lower odds ratio for female subjects ( OR = 1.27,95% CI[ 0.93-1.75], p &lt; 0.001) than for male subjects ( OR = 1.86, 95% CI[ 1.40-2.42] ; p &lt; 0.001); higher odds ratio for college graduates (OR = 1.30, 95% CI [0.10-1.63] ; p = 0.001) than for other educational background groups and higher odds ratio for Caucasian descendants (OR = 1.63, 95% CI[ 0.93-2.0] ; p &lt; 0.085) than for African American descendants (OR = 1.59, 95% CI [1.28-1.98] ; p = 0.001) . The results showed a different odds ratio in each group which could be associated to social, cultural, environmental, and economic, educational and genetically different frequencies in allele’s risk factors in ethnicities. Based on these results the null hypothesis was rejected indicating that the alternative Hypothesis 1 was supported.
- Slide 51: Study Limitations The study used a correlational analysis approach, and did not analyze the causation between variables, and had provided only the significance of the associations between dependent and independent variables. The study statistical analyses were based on secondary datasets which were collected partially by self-reported responses. These factors might impact the internal validity of this study (Frankfort-Nachimias & Nachimias, 2008). Change in environmental, social, cultural, economic, geographical location, and demographic factors that affect genes structure and function in other populations might prevent the generalizability of findings from this study. The extreme variability of CYP2A6 and CYP2B6 gene variants across ethnicities and variability of genes frequencies might also limit the generalizability of these results (Khoury et al., 2010). Participants in this study were recruited from the population of nicotine dependent persons who wanted to be treated, creating low sample size, and power, and small genetic effect size problems which might limit the generalizability of findings (Kortmann, L.G., Dobbler, C. J., Bizarro, L., & Bau, H. D. C. et al., 2010). Only two subsets of ethnicities (Caucasian and African American descendants) were represented in this study limiting the application of these findings to others ethnicities.
- Slide 52. Recommendations for action Although, the results of this study could be used to design successful nicotine addiction treatment, many obstacles remain to be overcome to fully integrate findings in successfully individualized medicine and public health practice. Therefore, (a) the study should be replicated in other populations with more diverse ethnicities, (b) with bigger sample sizes, and (c) using more sets of alleles to test other gene-gene and gene-environmental interactions.
- Slide 53: Social Implications Today, there is a lack of translating gene variants clinical potential and health benefit information into treatment and health problems assessment due to the complexity of gene-gene and environmental factors . Findings of this study could be used to improve genetic profiling, gene screening, and testing results interpretation and facilitate individualized nicotine dependence treatment planning, and improve the assessment of nicotine gene risk factors in diagnosis and treatment. May help to understand genes clinical potential and advance individualized disease treatment. The study could motivate parents to use the screening and gene testing results of their children to guide and advise them to avoid nicotine exposure (if they are carriers of normal nicotine metabolizers) since most of adults who are nicotine dependent were adolescents who had been exposed to smoking at an earlier age (Remington, Brownson, & Wegner, 2010). Also, cognitive behavioral therapy which consists of advising and motivational interventions might also use these study findings as treatment guidelines.
- Slide 54-Statement: Existing nicotine dependence therapies have decreased smoking prevalence in the United States, but the decline in the number of adult smokers is stalling, due, in part, to the limited efficacy of current therapies that lack treatment personalization. Cytochrome P450 2A6 (CYP2A6) gene variants are known to metabolize nicotine and possibly influence nicotine dependence treatment. These genes’ inconsistent information, interindividual variability, interactions with other genes, and environmental factors have made it difficult to use their information to improve nicotine dependence therapy. Method and Design: This cross-sectional study based on behavioral genetic theory stating that environmental and genetic factors cause behavioral disorders, assessed the impact of slow nicotine metabolizers (CYP2A6*1H, CYP2A6*4A, CYP2A6*9, and CYP2A6*12A) and normal (fast) nicotine metabolizers (CYP2A6*1A) gene variants and their interactions with CYP2B*6 associated with nicotine therapy type and nicotine dependence and withdrawal syndromes on nicotine dependence outcome. Results: CYP2A6*4A (OR = 1.60, CI [1.13-1.95]; p &lt; 0.001) and CYP2A6*9A (OR = 1.47, CI[1.18-1.88] ; p &lt; 0.001) were the most linked to the highest odds of successful treatment outcome, indicating that carriers of slow nicotine metabolizers were more likely to maintain abstinence 6 months post period treatment than normal (fast) metabolizer CYP2A6*1A (OR = 1.35, 95% CI[ 1.11-1.70] ; p &lt; 0.003) carriers. Social Implications: Study findings may be useful in gene counseling and nicotine gene therapy to tailor individualized nicotine clinical treatments, to increase smoking quit rates, and to induce positive social change by improving the lives of smokers and their families.
- Slide: 55 End note and Questions. Thank you for all you have done for me to make this project a success.