Role of the cholinesterase inhibitors in the treatment of schizophrenia.

The effects of cognitive impairment on the occupational functioning, social activity, and economic life of patients with schizophrenia constitute major obstacles to recovery. Currently, the standard biological treatment for schizophrenia consists of antipsychotic medications, which results in significant improvements in psychotic symptoms such as delusions and hallucinations via a high affinity for numerous neurotransmitter receptors. However, the effects of antipsychotics on cognitive dysfunction appear very limited or minimal in clinical practice. In fact, according to recent clinical trials, newer antipsychotics, which have little effect on cholinergic receptors but potent antagonistic effects on the serotonin-7 receptor (5-HT(7); e.g., lurasidone), may ameliorate cognitive defects in patients with schizophrenia. It has been consistently reported that both nicotinic and muscarinic receptors play crucial roles in cognition and, thus, that they may be considered potential therapeutic targets for new drugs designed to decrease cognitive deficits. Accordingly, cholinesterase inhibitors (ChEIs) may be effective in enhancing the cognitive functioning of patients with schizophrenia. Not surprisingly, such drugs have been utilized to treat cognitive deficits in patients with schizophrenia in a handful of clinical trials. This paper reviews a brief background information and discusses current clinical issues regarding the use of ChEIs in patients with schizophrenia.