Theoretical Models of Depression:A. Biological Model1. Genetics- Heritability estimate: 30-40% female; 20-30% male- Serotonin transporter gene (chromosome 17)Long versus short versions: long (L) = protective; short (S) = risk4+ severe negative events: LL = 17% depressed; SS = 43% depressed2. Neurobiology- Multiple neurotransmitter systems involved- Serotonin: social drive, stress response, amygdala, anterior cingulate- Dopamine: pleasure/reward, goal-directed activity, initiative, motivation(also Glutamate, Norepinephrine, Acetylcholine, etc.)- CRH – “master protein” regulates neurotransmitter function in brain, coordinates stress response 3. Neuroendocrine (hormones)- Cortisol (stress hormone)Runaway stress response body shutdown Toxic to brain – reduced BDNF (brain-derived neurotophic factor)- Inflammatory hormones: promote brain’s stress response shutdown 4. Frontal Cortex – reduced left frontal activity 5. Sleep Architecture – increased REM, decreased slow wave sleepB. Environmental Mutation (Ilardi)- Humans lived in hunter-gatherer conditions for 99% of existence- Modern-day aboriginal peoples (e.g., Kaluli of New Guinea) rarely get depressed- The more “modern” a society, higher rate of depression(U.S. today = 23%; U.S. 1940s = 2-3%; developing nat. = 2-5%; Amish = 2%)- Why? Built-in antidepressant and protective features of ancient life:1. aerobic exercise (increases BDNF, serotonin & dopamine function)2. omega-3 fatty acids (1000-2000 mg EPA, also DHA)3. natural sunlight (10,000 lux): reset body clock, make Vitamin D especially for seasonal onset depression4. sleep (target 8 hrs)5. social connection/community6. engaging activity vs. idle alone time (rumination)- Therapeutic Lifestyle Change (TLC): www.psych.ku.edu/TLCC. Psychodynamic Model- For Freud, depression = “anger turned inward”- Personality factors: oral or anal fixation --> dependency, perfectionismD. Cognitive Model- Beck’s model: depression caused by negatively biased thoughts- Automatic thoughts – involuntary negative interpretation of events- Logical errors – give rise to automatic thoughts (ex: “all-or-nothing thinking”)- Schemas – core beliefs, taken as a given (“I’m a loser; No one will ever love me”)Treating Depression:A) Drug Treatments:1. SSRIs (Prozac, Paxil, Zoloft, Celexa, Lexapro)SNRIs (Effexor/Pristiq, Cymbalta)- Short term: Full recovery: 20-35%; “favorable response”: 40-60%- Across 47 studies in FDA database, meds beat placebo in fewer than half of studies: overall, placebo ~ 80% of drug response-For depression of mild, moderate, seveere severity, SSRI/SNRI roughly equal to placebo (sugar pill) in response rates-Only in very severe depression: meds clearly superior to placebo-High relapse rates when SSRI/SNRI discontinued-STAR*D Trial: > 4000 patients, start on Celexa, keep trying new meds until patient recovers: < 6% of all patients fully recover for 1 year-Standard of care: 1 year for 1st depression; 2 years for 2nd; 5+ years for 3rd2. Tricyclics (imipramine/Tofranil, amitriptyline/Elavil)- Similar response rate as SSRI, but lethal overdose potential- Until 20 years ago, most popular antidepressant; now less widely used 3. Atypical antidepressants (Wellbutrin, Remeron, etc.)- Wellbutrin works on dopamine/reward circuits (spontaneous orgasm)- Remeron hits dopamine & serotonin circuits, evidence of highest responserate (but major weight gain) 4. St. John’s Wort (hypericum)- Largest U.S. study: St. John’s = placebo, but both = Zoloft!)B) Electroconvulsive Therapy (ECT):- Electric current passed through cortex convulsive seizures- Typical ECT regimen: 3 times per week, 2-4 weeks- 80% response rate, but only 50% of med non-responders- Used lots with elderly- Very high relapse rates (most relapse in year following treatment)- Permanent cognitive impairment (especially memory)C) Psychotherapy1. Cognitive Therapy (CT)- Aaron Beck – developed in 1960’s- Most widely researched form of psychotherapy – dozens of well-conducted research studies- 16-20 sessions over 3-4 months- 50-60% favorable response rates (short term)- Focus on cognitive modification (i.e., identify and change negative thoughts) and behavioral activation2. Interpersonal Therapy (IPT)- Psychodynamic, short-term- Less well researched, but available evidence suggests
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