There were 24 included studies with 11959 participants in total. Many studies were of cross-over design and first-phase data were unavailable, or could not be extracted. Global impression of change (GIC) was the only outcome for which pooling of data was possible, involving only four studies. There was evidence of heterogeneity in the results, Chi2 test = 19.17 (df = 3, P < 0.001). The odds ratio ( OR ) for improvement in the piracetam group compared with placebo was 3.43 (95% confidence interval ( CI ) 2.32 to 5.07). Using a fixed-effect model, the OR for improvement with piracetam compared with placebo was 3.55 (95% CI 2.45 to 5.16). This estimate was derived from completers rather than from an intention-to-treat analysis as relevant data could not be extracted from the reports.

In the limited data available, no significant differences were found between treatment and placebo groups for cognition (immediate memory, visuospatial, Mini Mental Status Examination (MMSE), delayed memory or speech) for dependency, or for depression.