Biological Approach to SZ Psychology

Biological explanation of Sz The dopamine hypothesis if the oldest and most established hypothesis of sz Dopamine is a neurotransmitter which is a chemical messenger transmitted across the brain It is believed that there is an excess of d2 receptors causing an excess of dopamine at the post- synaptic membrane- the receiving end of a neurone There is a different number of D2 receptors in different parts of the brain which is why schizophrenics suffer from a range of different symptoms

It is believed that the mesolimbic pathway (midbrain- known as the reward pathway) may be responsible for positive symptoms. Mesocortical pathway (frontal lobe-motivation, emotion and thought) may be responsible for negative symptoms Pet scans, twin studies, animal studies, post mortems and drug treatment have all been used to investigate this hypothesis. Evidence and validation for this hypothesis has come from treatments for sz such as antipsychotics.

Evaluation- strengths Research into the dopamine hypothesis have used a range of different methods to collect data, PET scans, twin studies, animal studies etc this improves Many studies have been replicated and similar results found i.e. an excess of d2 receptors. This therefore means that the hypothesis can be considered Donnelly et al measures homovanillic acid in szchizophrenic sufferes which is a waste product of dopamine. They found an increase in the acid in comparison to non-schizophrenic suffers

Evaluation- weaknesses Some of the research on the dopamine hypothesis has involved animals. However whilst there are differences between humans and animals there are some structures that are very similar such as biological structures and nervous systems. This approach fails to take into account that social and environmental factors may contribute to the development of sz. The social drift hypothesis states that

Antipsychotic drugs used to reduce symptoms of sz immediately block dopamine receptors in the brain but the symptoms (positive) take a few days to reduce. This may therefore mean that the dopamine hypothesis may not be the only explanation Is an excess of dopamine the cause of the disorder or the effect of having sz?

Over to you Read the handout on the Social Drift hypothesis and identify key features of the Social Drift hypothesis. Identify similarities and differences between the biological approach and the social drift hypothesis in explaining sz