Two review authors selected studies for inclusion and extracted data independently. We assessed risk of bias in the included studies using the Cochrane 'Risk of bias' tool. Where clinically appropriate, we pooled data for treatment periods up to three months and from three to nine months. We used GRADE methods to assess the overall quality of the evidence.
MAIN RESULTS: We included ten studies with a total of 1592 patients. Eight included studies reported sufficiently detailed results to enter into analyses related to
antidepressant efficacy. We split one study which included two different
antidepressants and therefore had nine groups of patients treated with
antidepressants compared with nine groups receiving placebo treatment. Information needed to make 'Risk of bias' judgements was often missing.We found high-quality evidence of little or no difference in scores on depression symptom rating scales between the
antidepressant and placebo treated groups after 6 to 13 weeks (standardised mean difference (SMD) -0.10, 95% confidence interval (CI) -0.26 to 0.06; 614 participants; 8 studies). There was probably also little or no difference between groups after six to nine months (mean difference (MD) 0.59 point, 95% CI -1.12 to 2.3, 357 participants; 2 studies; moderate-quality evidence). The evidence on response rates at 12 weeks was of low quality, and imprecision in the result meant we were uncertain of any effect of
antidepressants (
antidepressant: 49.1%, placebo: 37.7%; odds ratio (OR) 1.71, 95% CI 0.80 to 3.67; 116 participants; 3 studies). However, the remission rate was probably higher in the
antidepressant group than the placebo group (
antidepressant: 40%, placebo: 21.7%; OR 2.57, 95% CI 1.44 to 4.59; 240 participants; 4 studies; moderate-quality evidence). The largest of these studies continued for another 12 weeks, but because of imprecision of the result we could not be sure of any effect of
antidepressants on remission rates after 24 weeks. There was evidence of no effect of
antidepressants on performance of
activities of daily living at weeks 6 to 13 (SMD -0.05, 95% CI -0.36 to 0.25; 173 participants; 4 studies; high-quality evidence) and probably also little or no effect on cognition (MD 0.33 point on the Mini-Mental State Examination, 95% CI -1.31 to 1.96; 194 participants; 6 studies; moderate-quality evidence).Participants on
antidepressants were probably more likely to drop out of treatment than those on placebo over 6 to 13 weeks (OR 1.51, 95% CI 1.07 to 2.14; 836 participants; 9 studies). The meta-analysis of the number of participants suffering at least one adverse event showed a significant difference in favour of placebo (
antidepressant: 49.2%, placebo: 38.4%; OR 1.55, 95% CI 1.21 to 1.98, 1073 participants; 3 studies), as did the analyses for participants suffering one event of dry mouth (
antidepressant: 19.6%, placebo: 13.3%; OR 1.80, 95% CI 1.23 to 2.63, 1044 participants; 5 studies), and one event of
dizziness (
antidepressant: 19.2%, placebo: 12.5%; OR 2.00, 95% CI 1.34 to 2.98, 1044 participants; 5 studies). Heterogeneity in the way adverse events were reported in studies presented a major difficulty for meta-analysis, but there was some evidence that
antidepressant treatment causes more adverse effects than placebo treatment does.
AUTHORS' CONCLUSIONS: The available evidence is of variable quality and does not provide strong support for the efficacy of
antidepressants for treating depression in
dementia, especially beyond 12 weeks. On the only measure of efficacy for which we had high-quality evidence (depression rating scale scores),
antidepressants showed little or no effect. The evidence on remission rates favoured
antidepressants but was of moderate quality, so future research may find a different result. There was insufficient evidence to draw conclusions about individual
antidepressant drugs or about subtypes of
dementia or depression. There is some evidence that
antidepressant treatment may cause adverse events.