Acetyl-Cholinesterase inhibitor as Add-On Medication in Schizophrenia: A controlled study

Objective: Problem with memory and attention is a neglected aspect of schizophrenia. The most affected domains are attention, working memory and semantic memory. The impairments are, like the negative symptoms, basically stable and independent of the positive symptoms. Since such deficits do not respond to antipsychotics, during the past years some approaches have been done by different acetylcholinesterase inhibitors. Assessment of the effectiveness of rivastigmine, as an add-on therapy, on clinical symptoms of schizophrenia, was the main objective of the present study.

Methods: 46 male inpatients, with diagnosis of schizophrenia, entered a 12-week, double-blind, clinical trial for random assignment to placebo or rivastigmine, as adjuvant to their current antipsychotic medication. ‘Positive and Negative Symptom Scale (PANSS)’ and ‘Mini Mental State Examination (MMSE)’ had been used as the main outcome scales. ‘Clinical Global Impressions- Global Improvement (CGI-I)’ and ‘Extrapyramidal Symptom Rating Scale (ESRS)’ had been used as the ancillary scales.

Results: According to the findings, except than significant enhancement of MMSE by rivastigmine (p<0.001), no significant improvement in positive, negative and general psychopathology of schizophrenia was evident in the target and control groups. Also, except than significant enhancement of CGI-I by rivastigmine in intra-group analysis, no significant improvement was apparent in between- group analysis. ESRS, too, did not display any significant alteration in either group. Finally, effect size (ES) analysis exhibited a large improvement of MMSE by means of rivastigmine.

Conclusion: Disregard to positive or negative symptoms, rivastigmine can significantly improve the cognitive function of schizophrenic patients, which may be favorable for psychosocial intervention or rehabilitation of this group of patients.

Keywords: Schizophrenia; Acetylcholinesterase inhibitors; Rivastigmine