Summary of findings for the main comparison. B vitamins compared to placebo for maintaining cognitive function in cognitively healthy people in mid and late life.
| B Vitamins compared to placebo for maintaining cognitive function in cognitively healthy people in mid and late life | ||||||
| Patient or population: cognitively healthy people in mid and late life Setting: community Intervention: B Vitamins (folic acid, vitamins B6 and vitamin B12, alone or in combination) Comparison: placebo | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with placebo | Risk with B Vitamins | |||||
| Overall cognitive functioning 3 to 12 months of supplementation (final measurement data) assessed with: MMSE or TICSm |
‐ | SMD 0 (0.08 lower to 0.08 higher) | ‐ | 2556 (3 RCTs) | ⊕⊕⊕⊝ MODERATE 1 | |
| Overall cognitive functioning 3 to 12 months of supplementation (change from baseline data) assessed with: MMSE or TICSm |
‐ | SMD 0.03 lower (0.26 lower to 0.19 higher) | ‐ | 317 (2 RCTs) | ⊕⊕⊝⊝ LOW 1 2 | |
| Overall cognitive functioning > 1 to 2 years of supplementation (final measurement data) assessed with: MMSE, TICS, or TICSm |
‐ | SMD 0.15 higher (0.17 lower to 0.47 higher) | ‐ | 6956 (5 RCTs) | ⊕⊕⊕⊝ MODERATE 1 | |
| Overall cognitive functioning > 1 to 2 years of supplementation (change from baseline data) assessed with MMSE |
‐ | SMD 0.06 higher (0.2 lower to 0.31 higher) | ‐ | 241 (1 RCT) | ⊕⊕⊝⊝ LOW 1 2 | |
| Overall cognitive functioning > 2 to 5 years of supplementation (final measurement data) assessed with MMSE, TICS, F‐TICSm or a composite score |
‐ | SMD 0.01 lower (0.11 lower to 0.09 higher) | ‐ | 3985 (4 RCTs) | ⊕⊕⊕⊝ MODERATE 1 | |
| Overall cognitive functioning ‐ > 5‐10 years of supplementation (final measurement data) assessed with MMSE, TICS or TICSm |
‐ | SMD 0.01 lower (0.09 lower to 0.07 higher) | ‐ | 10249 (3 RCTs) | ⊕⊕⊝⊝ LOW 1 3 | |
| Incidence of MCI or dementia > 2 to 5 years of supplementation assessed with: MMSE < 24 on 2 or more occasions follow‐up: median 2.8 years | Study population | RR 0.89 (0.67 to 1.18) | 1803 (1 RCT) | ⊕⊕⊕⊝ MODERATE 1 | ||
| 103 per 1.000 | 91 per 1.000 (69 to 121) | |||||
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; RR: Risk ratio; OR: Odds ratio; | ||||||
| GRADE Working Group grades of evidence High certainty: We are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect | ||||||
1 Downgraded for indirectness due to restricted inclusion criteria for participants in included studies
2 Downgraded for imprecision due to small sample size and wide confidence intervals
3 Downgraded for study limitations due to missing data from 26% of participants in SEARCH 2010
MMSE: Mini Mental State Examination TICS: Telephone Interview for Cognitive Status TICSm: modified Telephone Interview for Cognitive Status F‐TICSm: modified Telephone Interveiw for Cognitive Status (French version)