- Design
- Systematic review and dose-response meta-analysis of RCTs
- Population
- 27 RCTs, 2034 adults aged ≥60 with mild cognitive impairment
- Primary outcome
- Global cognition and cognitive domains
- Effect
- Global cognition g 0.67 (0.49–0.78); processing speed g 0.45 (0.30–0.60); 240 min/week g 0.37 with ≥11 weeks
This meta-analysis pooled 27 randomised trials (2034 people aged 60 or over with mild cognitive impairment) of mind-body exercise — tai chi, qigong, yoga and similar — and modelled how dose related to effect.
Global cognition improved (Hedges g 0.67, 95% CI 0.49 to 0.78) and processing speed improved (0.45, 0.30 to 0.60), on moderate-certainty evidence. The dose-response for global cognition was U-shaped: around 240 minutes a week still gave a significant effect (0.37), provided the programme ran for at least 11 weeks. Memory showed a similar pattern at very low certainty.
The practical message is duration over intensity. Longer programmes were associated with larger benefit, so a patient with MCI who keeps going with a yoga or tai chi class for three months or more is more likely to gain than one who stops after a few weeks. Yoga is widely available and culturally familiar in India.
- Recommend a mind-body programme such as yoga or tai chi to older adults with mild cognitive impairment.
- About four hours a week still gave benefit when continued for at least 11 weeks; this dosing finding needs confirmation.
- Encourage continuing for at least three months; longer programmes were associated with larger benefit.
- Combine with management of hearing, vision, blood pressure and mood, which also affect cognition.
- Reassess cognition at six to twelve months with the same tool.
Why it matters
It suggests a dose and duration, still to be confirmed, for an intervention patients can do in their own community.
Don't overread it
The dose-response curve was derived across trials with clustered doses; the 240-minute figure needs prospective confirmation.
The statistics, in plain English
Hedges g of 0.67 is a moderate-to-large effect on cognitive test scores. A U-shaped curve means benefit was not simply 'more is better'; the lowest point still helped, but only with longer duration.
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