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Unit 5 epidemiology schizophrenia

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Unit 5 epidemiology schizophrenia

  1. 1. The Epidemiology of Schizophrenia
  2. 2. Prevalence <ul><li>Following the introduction of the DSM-III, the prevalence of schizophrenia is estimated at 1.4 to 4.6 per 1,000 (Jablensky 2000) </li></ul><ul><li>In 1990, the US National Comorbidity Survey (NCS) estimated lifetime prevalence to be 1.4 per 1,000 </li></ul>Source: Bromet EJ, Dew MA, Eaton WW. Epidemiology of psychosis with special reference to schizophrenia. In: Textbook in Psychiatric Epidemiology , MT Tsuang and M Tohen, eds. Wiley-Liss Inc., 2002: NY.
  3. 3. Incidence <ul><li>Median annual incidence rate per 1,000 from studies published between 1950 and 1986 (Eaton et al., 1988): </li></ul><ul><ul><li>0.2 (11 case register studies) </li></ul></ul><ul><ul><li>0.22 (8 sites in the World Health Organization DOSMED study) </li></ul></ul><ul><ul><li>0.35 (4 community studies) </li></ul></ul><ul><li>Median annual incidence rate per 1,000 from studies published after 1985 (Eaton 1999) </li></ul><ul><ul><li>0.16 </li></ul></ul><ul><ul><li>Lower due to narrowing of diagnostic criteria </li></ul></ul>Source: Bromet EJ, Dew MA, Eaton WW. Epidemiology of psychosis with special reference to schizophrenia. In: Textbook in Psychiatric Epidemiology , MT Tsuang and M Tohen, eds. Wiley-Liss Inc., 2002: NY.
  4. 4. Age of Onset (AOO) <ul><li>Age at onset typically based on studies that use age at first hospitalization </li></ul><ul><li>Males develop schizophrenia at an earlier age than females </li></ul><ul><ul><li>Onset: early 20s in males </li></ul></ul><ul><ul><li>Late 20s to early 30s in females </li></ul></ul>Source: Bromet EJ, Dew MA, Eaton WW. Epidemiology of psychosis with special reference to schizophrenia. In: Textbook in Psychiatric Epidemiology , MT Tsuang and M Tohen, eds. Wiley-Liss Inc., 2002: NY.
  5. 5. Sociodemographic Factors Associated with Schizophrenia <ul><li>Social class </li></ul><ul><ul><li>Low socioeconomic status is associated with an elevated risk of schizophrenia </li></ul></ul><ul><ul><li>It is unclear whether low socioeconomic status precedes schizophrenia, or is the result of the early stages of illness </li></ul></ul><ul><li>Age </li></ul><ul><li>Gender </li></ul>
  6. 6. Risk Factors for Schizophrenia <ul><li>Family history (Jones and Cannon 1998; Murray et al. 1986) </li></ul><ul><ul><li>Overall heritability estimate: 60-70% of the variance in liability to schizophrenia is attributable to genetic factors </li></ul></ul><ul><ul><li>Risk in monozygotic twins was found to be >50% </li></ul></ul><ul><ul><li>Risk in dizygotic twins and siblings: 15% </li></ul></ul><ul><ul><li>Risk in children of two schizophrenic parents: 46.3% </li></ul></ul><ul><ul><li>Risk in children of one schizophrenic parent: 12.8% </li></ul></ul>Source: Bromet EJ, Dew MA, Eaton WW. Epidemiology of psychosis with special reference to schizophrenia. In: Textbook in Psychiatric Epidemiology , MT Tsuang and M Tohen, eds. Wiley-Liss Inc., 2002: NY.
  7. 7. Potential Risk Factors for Schizophrenia <ul><li>Season of birth </li></ul><ul><ul><li>5 to 15% higher risk for those born during winter </li></ul></ul><ul><ul><li>Weak association; may be a proxy for underlying factors like viral infections or diet during pregnancy </li></ul></ul><ul><li>Obstetric / birth complications </li></ul><ul><ul><li>Twofold increase in risk for offspring of nutritionally deprived mothers during the Dutch Hunger Winter of 1944-1945 </li></ul></ul><ul><li>Substance abuse </li></ul><ul><li>Stress </li></ul>Source: Bromet EJ, Dew MA, Eaton WW. Epidemiology of psychosis with special reference to schizophrenia. In: Textbook in Psychiatric Epidemiology , MT Tsuang and M Tohen, eds. Wiley-Liss Inc., 2002: NY.
  8. 8. Potential Risk Factors for Schizophrenia <ul><li>Geographic location </li></ul><ul><ul><li>World Health Organization found similar incidence in diverse populations around the world </li></ul></ul><ul><ul><li>Urban environment poses greater risk than rural </li></ul></ul><ul><ul><li>Patients in developing countries tend to have a more benign course of illness </li></ul></ul>Source: Bromet EJ, Dew MA, Eaton WW. Epidemiology of psychosis with special reference to schizophrenia. In: Textbook in Psychiatric Epidemiology , MT Tsuang and M Tohen, eds. Wiley-Liss Inc., 2002: NY.

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