Summary of findings 4. Zinc + copper compared to placebo for maintaining cognitive function in cognitively healthy people in mid and late life.
| Zinc + copper 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: Zinc + copper oxides 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 Zinc + copper | |||||
| Overall cognitive functioning assessed with: 3MS Scale from: 0 to 100 follow‐up: median 6.9 years | The mean 3MS score was 92.1 | MD 0.6 higher (0.19 lower to 1.39 higher) | ‐ | 1072 (1 RCT) | ⊕⊕⊕⊝ MODERATE 1 2 | |
| Incidence of dementia or MCI assessed with: 3MS score < 80 follow‐up: median 6.9 years | 4.5% of participants met the authors' definition of cognitive impairment (3MS < 80) and "there was no significant effect of treatment group on likelihood of having cognitive impairment." | ‐ | 1072 (1 RCT) | ⊕⊕⊝⊝ LOW 3 | ||
| *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 risk of bias due to unclear selective reporting and high risk of bias due to incomplete outcome data
2 Downgraded for indirectness (Yaffe 2004 included participants with age‐related macular degeneration)
3 Downgraded two levels for study limitations due to incomplete outcome data and selective reporting
3MS: The Modified Mini‐Mental State Examination MCI: Mild cognitive impairment