Abstract

The accidental discovery (in the 1950s) and subsequent development of antipsychotic drugs have revolutionized the care of many patients with the schizophrenic psychoses. The first-generation antipsychotics, though effective for hallucinations, delusions, as well as a treatment of the disorder in two-thirds of patients with schizophrenia, burdened many patients with extrapyramidal effects (EPS), including dystonias, akathisia, and pseudo-Parkinsonian morbidity. Moreover, they had little or no effect on the most disabling, core symptoms associated with withdrawal of interests and interpersonal relationships. The second-generation antipsychotics, which began to appear in the late 1980s with the introduction of clozapine, had strikingly less morbidity, contributing little or no EPS and providing at least modest promise of reduction of negative symptoms and enhancement of some aspects of cognition. However, some secondgeneration antipsychotics have induced considerable weight gain, and appear to lower the threshold for the development of the metabolic syndrome, which increases cardio-vascular morbidity. The actual mechanism(s) of action of the antipsychotic drugs is still in dispute. Direct and indirect effects on dopamine transmission have been supported by much of the evidence. Direct blockade of dopamine hyperactivity and partial restoration deficient dopamine has been the standard explanation of their effects. However, dysfunctional intracellular signal transduction and dysfunction of myelin are emerging as competing pathologies upon which antipsychotics act. It is likely that the next generation of antipsychotics will act more directly and more specifically on such underlying neuropathology.

Keywords: Antipsychotics, atypical antipsychotics, dopamine, serotonin, response, psychosis, negative symptoms, neurocognition