Dopamine hypothesis mechanism

1. Dopamine hypothesis—The dopamine hypothesis of schizophrenia proposes that the disorder is caused by a relative excess of functional activity of the neurotransmitter dopamine in specific neuronal tracts in the brain.First, many antipsychotic drugs block brain dopamine receptors (especially D2 receptors). Second, dopamine agonist drugs (eg, amphetamine, levodopa) exacerbate schizophrenia. Third, an increased density of dopamine receptors has been detected in certain brain regions of untreated schizophrenics. The dopamine hypothesis of schizophrenia is not fully satisfactory because antipsychotic drugs are only partly effective in most patients and many effective drugs have a higher affinity for other receptors, than for D2 receptors.Phencyclidine (PCP) causes a psychotic syndrome but has no effect on dopamine receptors.