Biological Models

Biological Models

1. SMOKING

   • Initiation
     • Multiple genes - more likely A1 variant DRD2 gene.
     • Twin studies: heritability nicotine dependence: 60-70%
     • Inherited more sensitive mesolimbic dop/ path/w = higher dop/ levels.
     • Thorgeirsson et al (2008) - meta-analysis, 140,000 ppl - DNA variants ass/ smoking. Convincing = size.
       • Correlation. Genetics = predisposition, environmental trigger needed.
   • Maintenance
     • Nicotine Regulation Model: maintain nic/ levels - avoid with/d symp/s.
     • Lowered mood + concentration.
     • Drugs overstimulate dop/ path/w/s in mesolimbic reward path/w = flood brain (nucleus+NAcc) w/ dop/.
     • Dop/ = mood, emotion + motivation, reward. Inc/ = intense pleasure.
     • Schachter (1977) - double blind study. 4 weeks - low/high nicotine cigs each 1 week. Smoked more low nic/ (25% heavy smokers)
   • Relapse
     • Long-lasting changes - mesolimbic dop/ path/w deals w/ dop/.
     • Stopped = brain readjust = with/d/ symp/s. Severity = relapse.
     • MP = memory+motivation = highly sensitive to reminders, urge = vulnerable.
     • Calvert (2009) - ex-smokers: looking -cig/ packet = inc/ activity in Nacc = craving = biological trigger.
     • Lerman (2007) - abstained 1 night = inc/ blood flow - brain ass/ memory, reward, learning - active when craving.
   • Indiv/ diff/s: why some addicted, others w/ same envir/ experiences + life pressures dont. Vulnerable = gen/ predisposition.
   • Simple biol/ levels. Potential adv/s e.g...BUT ignores inf/s, social context, irrational thought processes.

2. GAMBLING

   • Initiation
     • A1 variant...Genetic component (Comings et al, 1996)
     • Slutske (2010) - concordance rates. 5000 inidiv/s, x2 MZs / DZs.
     • Not poss/ isolate genetic eff/s from environ/ + social eff/s. Diathesis Stress Model: genetics vulnerabilty + gambling role models (parents)
   • Maintenance
     • Activation dop/ system. "Buzz" = rise dop/ + adrenaline + brains reward system - need to maintain.
     • Social G's - rise in dop/ when actually gambling. Pathological - when anticipating/near stimulus.
     • To avoid with/d/ symp/s.
     • Chase + Clark (2010) - 24 G's. computerized game (slot), fMRI. Inc/ act/ - mesolimbic system - wins + near misses. Higher G severity = greater response.
     • Drugs - raise dop/ (treat Parkinsons) ass/ w/ inc/ risk impulse control disorders (gambling) (Dodd et al, 2005)
   • Relapse
     • Long-lasting changes...
     • Stopped = readjust...Severity = relapse
     • MP = areas of brain - memory, motivation = highly sensitive...
     • Same with/d/s as drugs. Wray + Dickerson (1981) - 60% Pathological G's - physical side effects (insomnia, loss appetite, muscle weakness, breathing difficulties). More severe.
   • Indiv/ diff/s: Some add/ others... Vulnerable=genetic predisposition.
   • Simple bio/ level...
   • Absolves addict of responsibility - genes/dop/ = relieves responsibility, less likely treatment successful.

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