The first clue to how typical antipsychotics work came from analysis of their neurological side effects. Since these drugs produce the same effects on movement as Parkinson’s disease, which is caused by a deficiency in the modulatory neurotransmitter dopamine, scientists reasoned that the drugs might act by reducing dopamine in the brain. They also reasoned, by extension, that schizophrenia might result in part from excessive action of dopamine. In other words, reducing dopamine in the brain might account for both the drugs’ therapeutic effects and their adverse side effects.
