Biological explanations AO1

Explain the dopamine hypothesis

• suggests schizo is caused by abnormal dopamine levels in certain brain areas

• dopamine is neurotrasmitter associated with reward motivated behaviour

• hyperdopaminergenic activity (high levels) found in mesolimbic pathway + subcortex of brain (e.g Broca's pathway may be associated with positive symptoms of schizo like halluciantions + speech poverty

• may be due to higher D2 receptors

• hypodopaminergic activity (low levels) found in mesocortical pathway esp in frontal lobs may be associated with negative symtpms like avolition + decision making

Explain genetic link theory

• suggests schizo is passed through genes from their families and makes some people genetically predispotioned to develop it

• Gottesman conducted a meta-analysis and found strong relationship between degree of genetic similarity + shared risk of schizo

• 48% concordance rates in MZ twins 17% for DZ twins - show genetics play a role in having risk of schizo

• believed that gene for schiz is polygenic (requires may genes) which increases vulnerability to developing it + is aetologically heterogenous so has a number of conditions that could lead to dveloping it

• Ripke et al foud 108 diff genetic variations for risk of schiz

Explain nerual correlates

• suggests abnormalities in specific brain areas are associated with development of schizo

• research using non-invasive scanning like fMRIs used to compare brain functioning of sufferers of shcizo + non-sufferers to indentify linked areas

• research found schizo ppl had enlarged ventricles (fluid filled gaps) which are associated with damage to central brain = pre-frontal cortex which is linked to negative symptoms - Tomoyuki did 10 yr longitudinal MRI study on 15 patients + 12 controls found schiz ppl had ventricle enlargements but not controls

• Allen et al found positive symptoms also related to neural correlates as scanned brains of patiens experiencing auditory hallucinations + compared them to control group whilst they identified pre-recorded speech and theirs or others

• found lower activation levels in superior temporal gyrus + anterior cingulate gyrus in schiz ppl who made more errors = lower neural activity is nerual correlate to auditory hallucination

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