Exercise gives working memory a lift in depression

Depression does not only affect mood — executive function, the set of mental skills that includes working memory, inhibition and cognitive flexibility, is among the cognitive dimensions it hits hardest. Exercise is already an established tool for mood, and there are grounds to think it might sharpen executive function too. But in adults with depression specifically, there has been no consensus on whether it actually does. This systematic review and meta-analysis set out to pin down what the controlled trials show across the three core executive domains.

The authors searched four electronic databases from inception until September 2022, combining keywords and medical subject headings. They included controlled interventions involving adults with depression that reported working memory, inhibition and/or cognitive flexibility data before and after an exercise programme. Seven studies met the criteria, together including 202 men and 457 women aged between 21.0 and 51.2 years with mild-to-moderate depression. Effect sizes were calculated as Hedges' g with 95% confidence intervals and pooled by meta-analysis.

For working memory, exercise groups showed a small, statistically significant advantage over controls (effect size 0.33; p = 0.026), though heterogeneity between trials was substantial (I2 = 64.9%). For inhibition, there was a small favouring effect (0.28) that did not reach significance. For cognitive flexibility, the effect was trivial (0.09) and also non-significant. So of the three executive domains examined, only working memory showed a reliable improvement, and even that came with considerable variation across studies.

This analysis adds behavioural evidence that exercise may benefit at least one component of executive function in depression, extending its better-known effects on mood. But the picture is narrower than enthusiasts might hope: two of the three domains showed no significant change. With only seven includable studies and high heterogeneity throughout, the authors themselves caution that the limited number of high-quality trials precludes firmer conclusions. Which exercise types, intensities and durations matter most remains an open question.

For anyone dealing with mild-to-moderate depression, this is a reason to think exercise might support certain thinking skills — particularly working memory, the ability to hold and juggle information — alongside its mood effects. It is not evidence that exercise sharpens every aspect of cognition, and the research base here is small and mixed. Exercise is best viewed as a possible complement to, not a replacement for, professional treatment for depression.