Trials were identified from the Cochrane
Dementia and Cognitive Improvement Group's Specialised Register, which is frequently updated from the major healthcare databases (MEDLINE, EMBASE, CINAHL, PsycINFO and Lilacs) as well as trial registers and grey literature.
SELECTION CRITERIA: Data were extracted from the published reports of the included studies, combined by meta-analysis where appropriate, and treatment efficacy and risk of adverse events were estimated.
MAIN RESULTS: Nine studies (from eight published reports) of 5149 individuals with
mild cognitive impairment (however defined) were included in the review. Limited pooling of results was possible owing to different lengths of trials. Meta-analysis of the three studies reporting conversion to
dementia gives no strong evidence of a beneficial effect of
cholinesterase inhibitors on the progression to
dementia at one, two or three years. The risk ratio (RR) for conversion at two years was significantly different from unity (0.67; 95% confidence interval (CI) 0.55 to 0.83), but this is based on only two studies reported in the same article. There was essentially no effect of
cholinesterase inhibitors on cognitive test scores.Based on the results from 4207 individuals, there were significantly more adverse events in the
cholinesterase inhibitor groups (RR 1.09; 95% CI 1.02 to 1.16), but no more serious adverse events or deaths. Gastrointestinal side effects were much more common (diarrhoea: RR 2.10; 95% CI 1.30 to 3.39;
nausea: RR 2.97; 95% CI 2.57 to 3.42;
vomiting: RR 4.42; 95% CI 3.23 to 6.05). Cardiac problems were no more likely in either group (RR 0.71; 95% CI 0.25 to 2.02). Other side effects reported significantly more often in the
cholinesterase inhibitor group were
muscle spasms/leg
cramps (RR 7.52; 95% CI 4.34 to 13.02),
headache (RR 1.34; 95% CI 1.05 to 1.71),
syncope or
dizziness (RR 1.62; 95% CI 1.36 to 1.93),
insomnia (RR 1.66; 95% CI 1.36 to 2.02) and abnormal dreams (RR 4.25; 95% CI 2.57 to 7.04).
AUTHORS' CONCLUSIONS: