Memory impairment in schizophrenia: A meta-analysis

Objective: Memory impairment is well documented in schizophrenia. Less is k nown, however, about the exact magnitude, pattern, and extent of the impair ment. The effect of potential moderator variables, such as medication statu s and duration of illness, is also unclear. In this article, the authors pr esented meta-analyses of the published literature on recall and recognition memory performance between patients with schizophrenia and normal comparis on subjects. Method: Meta-analyses were conducted on 70 studies that report ed measures of long-term memory (free recall, cued recall, and recognition of verbal and nonverbal material) and short-term memory (digit span). Tests of categorical models were used in analyses of potential moderators (clini cal variables and study characteristics). Results: The findings revealed a significant and stable association between schizophrenia and memory impairm ent. The composite effect size for recall performance was large. Recognitio n showed less, but still significant, impairment. The magnitude of memory i mpairment was not affected by age, medication, duration of illness, patient status, severity of psychopathology, or positive symptoms. Negative sympto ms showed a small but significant relation with memory impairment. Conclusi ons: This meta-analysis documented significant memory impairment in schizop hrenia. The impairment was stable, wide ranging, and not substantially affe cted by potential moderating factors such as severity of psychopathology an d duration of illness.