Affective Disorders - Psychiatry - Lecture Slides, Slides of Psychology

Download Affective Disorders - Psychiatry - Lecture Slides and more Slides Psychology in PDF only on Docsity! Mental Illness Schizophrenia Affective Disorders Anxiety Disorders Docsity.com  Affective Disorders  Symptoms of depression  Unipolar & Bipolar (Depression & Mania)  Antidepressants are all monoamine agonists  MAO inhibitors – iproniazid  Tricyclic antidepressants – imipramine  SSRIs – fluoxetine (Prozac)  Monoamine Theory of Depression  Cause – underactivity at NA and/or 5-HT synapses  Antidepressants act as agonists at these synapses  Mania  Lithium  Anticonvulsants, e.g. valproate  Diathesis-Stress Model of Depression  Neurogenesis Theory of Depression  Sleep and Depression  Animal models of depression Docsity.com Unipolar & Bipolar Affective Disorders • Out of those diagnosed with an affective disorder .. – Unipolar (depression only) – 60% – Bipolar (depression + mania) – 40% • Lifetime incidence of unipolar disorder – 5% – BIG sex difference ... • Lifetime incidence of bipolar disorder – 1-2% – No sex difference • ~ 10% commit suicide Docsity.com Unipolar & Bipolar Affective Disorders • As with schizophrenia, tendency to develop these problems is heritable. • Concordance rate: – 60% for identical twins – 15% for fraternal twins • Affected twins tend to suffer from the same type of disorder • Gene(s) have NOT been identified Docsity.com Causes of Depression • Stress??? • Stressful event can trigger attacks in people with depression • Little evidence that stress can increase the susceptibility to affective disorders Docsity.com MAOIs  Iproniazid (1957)  Monamine (NE, E, 5-HT) agonist  Increases the levels of monoamines by inhibiting the activity of monoamine oxidase (MAO)  MAO – enzyme that breaks down monoamine NTs in the cytoplasm of the neuron  Side effects  Cheese effect – dangerous increase in blood pressure - stroke  Foods that contain tyramine (increases blood pressure) – metabolized in the liver by MAO Docsity.com Tricyclic Antidepressants • Named on the basis of their chemical structure (3 rings) • Most block reuptake of NE & 5-HT – Imipramine (Tofranil) and Amitriptyline (Elavil) • Safer than MAOIs Docsity.com Selective Monoamine Reuptake Inhibitors SSRIs • Developed in late 1980s • Examples: – Prozac (fluoxetine), Paxil (paroxetine), Celexa (citalopram), Zoloft (sertraline), etc. – No more effective than tricyclic antidepressants – Few side effects – Effective against anxiety disorders as well as depression • Work by blocking the 5-HT transporter (5-HTT or SERT) and thereby blocking 5-HT reuptake. Docsity.com Mania • Drugs most commonly used to treat mania do not act on monoamine synapses • Metallic element – Lithium (Li) • More recently, drugs 1st used to treat epilepsy (anticonvulsants) have been used in combo with Li, e.g. Valproic acid or Valproate – GABA agonist & may also block voltage-dependent Na+ channels – reduce neural activity • These drugs are often called “mood stabilizers”. Docsity.com Effectiveness of Drugs • All drugs were equally effective • 25% of depressed subjects improve • Maintaining antidepressants after recovery or substituting cognitive behavior therapy reduces the likelihood of relapse Docsity.com Theories of Depression • Monoamine theory of depression • Diathesis-stress theory of depression • Neurogenesis theory of depression Docsity.com Monoamine Theory of Depression Pinel (2006)’s critique • “Overall, support for the monoamine theory of depression is weak. • “The main problem is that it is largely based on the fact that monoamine agonists are used to treat depressed patients, but this evidence is not so convincing when one considers that only about 25% of patients are actually helped by these treatments.” • Is this statement correct? Docsity.com Diathesis-Stress Model of Depression • Inherit a diathesis (genetic susceptibility) – incapable of initiating the disorder by itself • If susceptible individuals are exposed to stress early in life, their systems become permanently sensitized, and they overreact to mild stressors for the rest of their lives. • Support for this theory – Depressed people tend to release more stress hormones – Self reports Docsity.com Neurogenesis Theory of Depression • Exercise – Reduces depression – Increases adult neurogenesis in the hippocampus • Antidepressants increase adult hippocampal neurogenesis • Depression is associated with reductions in neurogenesis in the adult hippocampus Docsity.com