Cognitive function in schizophrenia--do neuroleptics make a difference?

Valid cognitive deficits in schizophrenia are now well characterised: general poor performance with disproportionate deficits in aspects of memory and executive function. Symptomatology, motivation, institutionalization, etc. cannot explain these deficits, which are of considerable importance for both the testing of theoretical models of schizophrenia and the determination of patients' functional outcome. The receptor blocking properties of neuroleptic treatments afford them the potential for interacting with monoaminergic, indoleaminergic, and cholinergic arousal systems in the brain and, hence, for modifying cognitive processes. However, the effects of conventional neuroleptics on cognition in schizophrenia are minor according to numerous studies. Atypical neuroleptics may, owing to their novel mechanisms of action, have the capacity to remediate cognitive impairment in schizophrenia: there is some evidence that clozapine has a "cognitive sparing" effect, but further research is needed in this area, particularly with other new drugs. Future studies should employ more appropriate methodology, particularly in terms of psychological/neurophysiological sophistication, patient evaluation, and applicability to real life, and should be hypothesis driven rather than purely empirical.