Biological Explanations for SZ

Stephanie Bates
Mind Map by , created over 5 years ago

A level Psychology A2 (Schizophrenia) Mind Map on Biological Explanations for SZ, created by Stephanie Bates on 04/03/2014.

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Stephanie Bates
Created by Stephanie Bates over 5 years ago
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Biological Explanations for SZ
1 GENETIC EXPLANATIONS
1.1 Genome scanning - 100s genes implicated. Advances - type 3 dopamine receptor gene (DRD3), type 2A serotonin receptor (HTR2A)
1.2 SZ run in families, controlled genetic studies - risk developing SZ inc/s w/ degree of genetic relatedness. Twin studies - conc/ rate higher MZs/DZs. Gottesman (1991) review studies since 1966 - conc/ rate MZs - 50%, DZs (children 1 affected parent) - 17%. Gen/ Pop? - 1%
1.3 MZs - not 100%. Other factors (environment)
1.4 MZs rare in population - of these 1% expected SZ. Sample sizes small. Cautious drawing conclusions.
1.5 Diff/ distinguish MZs + DZs. Rigorous study - Cardno et al (2002), Maudsley Twin Register, strict diagnostic criteria for SZ + accurate zygosity assessment - MZs-26.5%, DZs-0%
1.6 Adoption studies
1.6.1 Disentangle genetics / environmental factors - born to SZ parents, brought by ppl w/ no history of D
1.6.1.1 Tienari (1991) - Finnish Adoption Study - 155 adopt/d child/ - biological mothers had SZ. Compared to matched group adopted children - no fam/ hist/ SZ. 10% mothers SZ developed SZ, 1% 2nd Group.
1.6.1.1.1 Not complete explanation
2 BIOCHEMICAL EXPLANATIONS
2.1 Dopamine - neurotransmitter, limbic centre of brain.
2.2 Dop/ Hypothesis - SZ - excess dop/ activity at certain synaptic sites caused by:
2.2.1 Release excess dop/ by presynaptic neurons
2.2.2 Excess dop/ on receiving neurons = more dop/ binding to receptors = more neurons firing.
2.2.3 Oversensitivity in dop/ recep/s
2.3 Dop/ neurons - key role in guiding attention. Disturbances = probs w/ perception, attention + thought characteristics of SZs (Comer, 2003). Imbalance = inherited (genetic app/ (DRD3) or environment.
2.4 Antipsychotic drugs (dop/ antagonists e.g. phenothiazines) reduce symptoms. Block activity of dop/ - reduceing stimulation of dop/ system. Effectiveness = dop/ imbalance = sig/ contributory factor.
2.5 Post-Mortems - inc/ dop/ in left amygdala. Seeman (1987) - reviewed studies - inc/ dop/ receptor density, 60-100% / control groups.
2.6 Not all benefit phenothiazines - pos/ symptoms not neg/. Diff/ types SZ - Diff/ causes. Clozapine - oneof most clinically effective - bind dop/ + serotonin receptors. Serotonin imp/.
2.7 Post-Mortem - neuroleptic drugs. Inc/ dop/ = drugs? SZ?
2.8 Cause + Effect - correlated. dop/ = SZ or SZ = excess dop/, receptors more responsive. May be unknown variable.
3 Interaction - biol/+environment. Diathesis stress model - genetic vulnerability = physiological weakness (dop/ sys/). =process info abnormally. + disrupted fam/ communications