Chronic Stress and Impulsivity
Effect in Obesity
Imelda Medina, MD

1
Chronic Stress

Impulsivity

Food Intake

2
Hypothalamic Pituitary Adrenal Axis

3
Stress and biological response

Impact of uncontrollability and social evaluative elements
Meta-analysis review of 208 lab...
Impulsivity
• Impulsivity, "a force that moves something along" is a personality

trait which varies among individuals. Im...
Impulsivity-Significance
As stated in the DSM-IV

•

Impulse control disorders include:
ADHD
Intermittent explosive disord...
Impulsivity-Significance
• The essential feature of Impulse-control disorders is the

failure to resist an impulse, drive,...
How does Chronic Stress effects
Impulsivity?
• Pre-clinical and clinical studies have converged to show that

monoaminergi...
Dopamine Hypothesis of
Reward
• Postulates that the actions of drugs of

abuse are rewarding as a consequence of
activatio...
Obesity and Brain Reward

Human dopamine projections:
(1) The nigrostriatal projection, which is concerned with movement ....
Dopamine receptors and
obesity
(a) The upper pair of images
show dopamine receptor
availability in control and obese
parti...
What is the relationship between
Dopamine and Obesity?
• Obesity Song

– “What if you lack a
dopamine receptor,
that would...
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Chronic stress and impulsivity effect in obesity

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Chronic stress and impulsivity effect in obesity

  1. 1. Chronic Stress and Impulsivity Effect in Obesity Imelda Medina, MD 1
  2. 2. Chronic Stress Impulsivity Food Intake 2
  3. 3. Hypothalamic Pituitary Adrenal Axis 3
  4. 4. Stress and biological response Impact of uncontrollability and social evaluative elements Meta-analysis review of 208 laboratory studies of acute psychological stressors Dickerson SS and Kemeny ME 2004 Mean cortisol effect size for studies using cognitive tasks, public speaking/verbal interaction tasks, public speaking/cognitive combination tasks, noise exposure, and emotion induction. Public speaking/cognitive task combination yields the highest response. Mean cortisol effect size for studies using passive tasks, motivated performance tasks, uncontrollable motivated performance tasks, motivated performance tasks with social-evaluative threat, and uncontrollable motivated performance tasks with social-evaluative threat. Mean ACTH and cortisol effect sizes for motivated performance tasks with social-evaluative threat and uncontrolability and for tasks without both characteristics (ACTH =white column; cortisol=dark column). 4
  5. 5. Impulsivity • Impulsivity, "a force that moves something along" is a personality trait which varies among individuals. Important for normal behavior and adaptation. • Recent theories have decomposed impulsivity into 4 dimensions which include urgency, lack of premeditation (the inability to anticipate consequences), lack of perseverance (the inability to stick to one's task) and Sensation-seeking (the experience positive feelings towards risky actions). • Abnormal impulse control is central feature of multiple mental health conditions. • Impulsivity has been shown to be positively related to food intake. 5
  6. 6. Impulsivity-Significance As stated in the DSM-IV • Impulse control disorders include: ADHD Intermittent explosive disorder Kleptomania Pyromania Pathological gambling Trichotillomania Impulse-control disorder not otherwise specified • The following ocnditions may have features that involve problems of impulse control: Substance-related disorders paraphilias antisocial personality disorder conduct disorder schizophrenia mood disorders 6
  7. 7. Impulsivity-Significance • The essential feature of Impulse-control disorders is the failure to resist an impulse, drive, or temptation to perform an act that is harmful to the person or to others. • Usually, the individual feels an increasing sense of tension or arousal before committing the act and then experiences pleasure, gratification, or relief at the time of committing the act. • Following the act there may or may not be regret, selfreproach, or guilt. • Excessive food intake has been positively linked with dysfunctional impulsivity. 7
  8. 8. How does Chronic Stress effects Impulsivity? • Pre-clinical and clinical studies have converged to show that monoaminergic neurotransmitter systems (eg. dopamine) and the cortico-striatal circuitry are essential to impulse control. Basically, most evidence points toward that brain dopamine levels are inversely related to impulsivity. Low activity dopamine states are positively related to higher levels of impulsivity. • Pre-clinical and clinical evidence shows that chronic stress and resulting glucocorticoids affect the dopaminergic reward mesolimbic pathway. Chronic stress leads to a state of low dopamine activity in the brain and it has been observed to increase impulsivity. One of the possible ways is through its effect on dopaminergic neurons degeneration. 8
  9. 9. Dopamine Hypothesis of Reward • Postulates that the actions of drugs of abuse are rewarding as a consequence of activation of dopamine in the mesolimbic dopamine system. • A similar mechanism occurs with amphetamine, cocaine, nicotine and food. 9
  10. 10. Obesity and Brain Reward Human dopamine projections: (1) The nigrostriatal projection, which is concerned with movement . (2) and (3) The mesolimbic dopamine projection, which is involved in rewardrelated functions. 10
  11. 11. Dopamine receptors and obesity (a) The upper pair of images show dopamine receptor availability in control and obese participants. Note the clear difference between them. The lower pair of images show brain metabolic activity. Note that there is no difference between them. (b) The relationship between brain dopamine receptor availability and the degree of obesity. (Want GJ, Volkow ND et al 2001; Volkow ND and Wise RA 2005) 11
  12. 12. What is the relationship between Dopamine and Obesity? • Obesity Song – “What if you lack a dopamine receptor, that would hold back the feeling of rapture, and here is the case about dopamine secretion, you are more receptive to an obese transformation”. • http://www.youtube.co m/watch? v=bEfcwltXZ2Q 12
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