Cognitive training interventions and depression in mild cognitive impairment and dementia: a systematic review and meta-analysis of randomized controlled trials.

Background: Depression is common in people with cognitive impairment but the effect of cognitive training in the reduction of depression is still uncertain.
Aims: The purpose of this paper is to evaluate the effect of cognitive training interventions in the reduction of depression rating scale score in people with cognitive impairment.
Methods: Literature searches were conducted via OVID databases. Randomized controlled trials (RCTs) evaluated the effect of cognitive training interventions for the reduction of depression rating scale score in people with mild cognitive impairment (MCI) or dementia were included. Mean difference (MD) with 95% confidence interval (CI) was used to combine the results of Geriatric Depression Scale (GDS). Standardized mean difference (SMD) was used to combine the results of different depression rating scales. Subgroup analyses were conducted according to the types of cognitive training and severity of cognitive impairment, i.e. MCI and dementia.
Results: A total of 2551 people with MCI or dementia were extracted from 36 RCTs. The baseline mean score of GDS-15 was 4.83. Participants received cognitive training interventions had a significant decrease in depression rating scale score than the control group (MD of GDS-15 = -1.30, 95% CI = -2.14--0.47; and SMD of eight depression scales was -0.54 (95% CI = -0.77--0.31). In subgroup analyses, the effect size of computerized cognitive training and cognitive stimulation therapy were medium-to-large and statistically significant in the reduction of depression rating scale score.
Conclusions: Cognitive training interventions show to be a potential treatment to ameliorate depression in people with cognitive impairment.
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