Cognitive effects and antipsychotic treatment.

Cognitive impairment has long been recognized as central to the abnormalities that occur in schizophrenia, since neurocognitive deficits are predictive of a number of outcome indices, and they pose a significant obstacle to any attempts at social rehabilitation. This raises the possibility that treatments producing improvements in cognitive function might, in turn, prove to have synergistic effects with psychosocial interventions. Rather than improving cognitive deficits, conventional antipsychotics may instead contribute to the impairment seen in many patients with schizophrenia. These damaging effects on cognition might be expected not only when antipsychotic drugs with intrinsic anticholinergic properties are used but also when anticholinergic drugs are prescribed for the relief of treatment-emergent extrapyramidal symptoms. The atypical antipsychotic drugs may be effective in this area, either in amelioration of the cognitive impairments that occur in schizophrenia or in arresting any continuing decline. New-generation atypical agents, such as quetiapine and risperidone, have minimal intrinsic anticholinergic effects, which suggest that some of the additional negative effects on cognition can be avoided. A number of large-scale, long-term follow-up studies of atypical antipsychotics are currently underway, in 'real world' settings, to assess not only control of symptoms of schizophrenia but also improvement in social, occupational, and inter-personal functioning.