Psychology - Schziophrenia

Biological Explanations of Schizophrenia.


Psyhcology - Schizophrenia

One explanation is the biological explanation this is when the biological schizophrenic parents may have schizophrenia also the offspring to be put more in a risk to inherit this disorder. To support this claim many theories have been put forward to evident that if biological i.e. genetics is one of the main causes of the disorder.

Family Studies


This highlights that biological parents are 46% to develop this disorder.

Twin Studies


Gottesman and Gottesman (1991)

-         Monozygotic (MZ) twins (identical) have a 48% concordance rate of being diagnosed with schizophrenia.

-         Dizygotic (DZ) Twins (non-identical) have a 17% concordance rate being diagnosed with schizophrenia.

Adoption Studies


Schizophrenia rates are higher for schizophrenic children with schizophrenic biological parents (Kety et al 1975).

If identical twins were raised a part in different adoptive environments, can give the best evidence for genetic causes.

However genetic factors do not show a 100% concordance rate for schizophrenia. Environmental factors may also contribute to this.

Biochemical Causes


Dopamine Hypothesis – Over activity of the neurotransmitter, dopamine in the synapses of the brain caused Type 1 positive symptoms.

-         A dose of amphetamines (increase activity) creates amphetamine psychosis.

o    Acute Paranoid Schizophrenia. Small doses can trigger symptoms in schizophrenics.

Anti Schizophrenic drugs - Chlorpromazine block the post synaptic receptor sites of dopamine by reducing its activity.

-         If schizophrenics given increasing amount of these drugs. Schizophrenics develop symptoms similar to Parkinson’s disease.

Post Mortems and Positron Emission Tomography – higher amounts of dopamine and dopamine synaptic receptor sites.

Dopamine Hypothesis is an over simplistic explanation. New drugs (clozopine) work by affecting other neurotransmitters, especially serotonin.

Brain Structural Causes


Enlarged ventricles – Fluid filled cavities in the brain are larger in schizophrenics due to brain cells loss. Cell loss in the temporal lobes, are associated with negative symptoms.

Enlarged ventricles may be a symptom not cause. Non-schizophrenics can show them as well.

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