The impact of atypical antipsychotic medications on long-term memory dysfunction in schizophrenia spectrum disorder: a quantitative review

¹ Department of Psychology, Simon Fraser University; Burnaby, B.C., Canada V5A 1S6, Centre for Complex Disorders, Vancouver General Hospital; Vancouver, B.C., Canada V52 1M9 and Department of Medicine and Research, Riverview Hospital, Coquitham, B.C., Canada, V3C 4J2.
² Department of Psychology, Simon Fraser University; Burnaby, B.C., Canada, V5A 1S6
³ Department of Psychology, Simon Fraser University; Burnaby, B.C., Canada, V54 1S6.
⁴ Department of Psychiatry, University of British Columbia; Vancouver, B.C., Centre for Complex Disorders, Vancouver General Hospital; Vancouver, B.C. and Department of Medicine and Research, Riverview Hospital, Coquitham, B.C. Canada V3C 4J2.

^* To whom correspondence should be addressed.

	Abstract

This meta-analytic review examines the efficacy of antipsychotic medications in ameliorating schizophrenia-related long-term memory (LTM) impairments. Twenty-three studies were reviewed that compared schizophrenia spectrum patients treated (a) with atypical versus typical antipsychotic medications, or (b) with various atypical treatments. In 17 atypical versus typical trials aggregating 939 participants, superior overall (verbal and nonverbal) LTM was detected in patients assigned to atypical trials. However, this difference was small (effect size estimate (ES) 0.17; 95% Confidence Interval (CI) 0.04 to 0.31) and specific to certain atypical treatments. Relative to typical antipsychotic trials, LTM superiority was marginally significant for risperidone trials (ES 0.20; 95% CI -0.03 to 0.44) and significant for olanzapine trials (ES 0.29; 95% CI 0.08 to 0.49). In contrast, clozapine trials did not produce a LTM advantage over typical trials (ES -0.06; 95% CI -0.35 to 0.23). Due to the lack of available studies, the effect of quetiapine was indeterminate. Direct comparison between atypical trials revealed a similar effect pattern. A marginally significant superiority in overall LTM was detected for risperidone and olanzapine compared to clozapine (ES 0.28; 95% CI -0.04 to 0.59), which reached significance for verbal LTM (ES 0.36; 95% CI 0.04 to 0.67). Finally, the beneficial impact of antipsychotic medications emerged as a function of differences in the anticholinergic properties of the treatment arms being compared.

Key Words: schizophrenia, memory, cognition, atypical antipsychotic, pharmacotherapy, meta-analysis

First published on September 20, 2005, doi:10.1177/0269881105057002

Journal of Psychopharmacology 2006;20:335.

A more recent version of this article appeared on May 1, 2006


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