- Design
- Bayesian dose-response network meta-analysis of 38 randomised trials
- Population
- Adults aged ≥60 with mild cognitive impairment
- Primary outcome
- Working memory, cognitive flexibility and inhibitory control
- Effect
- Most reliable gains at about 300–1,000 MET-min/week; plateau above
A Bayesian dose-response network meta-analysis pooled 38 randomised trials of exercise programmes in adults aged 60 or over with mild cognitive impairment, measuring working memory, cognitive flexibility and inhibitory control. Exercise dose was standardised as MET-minutes per week.
The relationship was non-linear. Moderate doses of about 300 to 1,000 MET-minutes a week gave the most reliable improvements across all three domains, with higher doses plateauing or slightly declining. Exercise combined with cognitive training helped working memory most consistently, while combined physical training and aerobic walking gave steadier effects on flexibility and inhibitory control. Certainty was low to moderate.
As a rough guide, 150 minutes a week of brisk walking falls within that window. This is reassuring for older adults who cannot manage intense programmes: more is not necessarily better.
The practical change is to prescribe exercise in specific amounts, as a dose, and to add a cognitive element (dual-task exercise) where working memory is the concern.
- Prescribe roughly 150 minutes a week of moderate activity such as brisk walking for MCI.
- Add dual-task or cognitively demanding elements to target working memory.
- Reassure patients that moderate amounts, not intense programmes, gave the best results.
- Review adherence and adjust rather than escalate intensity.
Why it matters
It turns a general exhortation to exercise into a specific, achievable dose for people with MCI.
Don't overread it
Low-to-moderate certainty, and executive function scores are not the same as preventing dementia.
The statistics, in plain English
A MET-minute combines intensity and time; brisk walking is about 3 to 4 METs, so 150 minutes a week gives roughly 450 to 600 MET-minutes. Dose-response curves from many small trials are estimates, so the window is approximate.
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