Effects of reducing sedentary behaviour by increasing physical activity, on cognitive function, brain function and structure across the lifespan: a systematic review and meta-analysis.

Objective: To examine the acute and chronic effects of reducing prolonged sedentary time (ST) with physical activity (PA) on cognitive and brain health.
Design: Systematic review and meta-analysis.
Data Sources: PubMed, Scopus, CINAHL, PsycINFO, SPORTDiscus, Web of Science, and ProQuest Dissertation and Theses.
Eligibility Criteria: Randomised controlled trials (RCTs) published from inception to 17 June 2024, with healthy participants without cognitive impairment or neurological conditions that affect cognitive functioning, aged ≥4 years, testing acute and chronic effects of reducing ST and/or prolonged ST by reallocating ST to PA on cognitive function, brain function, and structure.
Results: We included 25 RCTs (n=1289) investigating acute (21 studies) and chronic (4 studies) effects on cognitive function (acute: n=20, chronic: n=4) and brain function (acute: n=7, chronic: n=1); there were no studies on brain structure. Acutely interrupting continuous ST with either multiple or a single PA bout improved cognitive function measured from 3 hours to three consecutive days based on 91 effect sizes ( g =0.17, 95% CI: 0.05 to 0.29, p=0.005, I ² =45.5%). When comparing single versus multiple PA bouts, only multiple PA bouts yielded a positive effect on cognitive function based on 72 effect sizes ( g =0.20, 95% CI: 0.06 to 0.35, p=0.006; I ² =48.8%). Chronic studies reported null findings on cognitive function (n=4), with some evidence of improved neural efficiency of the hippocampus (n=1).
Conclusion: Interrupting ST with PA acutely improves cognitive function. The evidence from chronic studies remains inconclusive.
Systematic Review Registration: PROSPERO CRD42020200998.
Competing Interests: Competing interests: None declared.
(© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)