Every row of the evidence table

Direction is for the test's accuracy against the reference standard; an accuracy result, not a health outcome. Plasma p-tau217 detected amyloid PET positivity with 82% sensitivity and 86% specificity, comparable to CSF p-tau217; less sensitive for tau PET.

Direction is for the test's accuracy against the reference standard; an accuracy result, not a health outcome. Plasma p-tau217 was the best-performing marker (88.1% sensitivity, 88.7% specificity, AUROC 91.1%, moderate certainty), ahead of p-tau181 and p-tau231; about 90% of studies were at high risk of bias.

Benefit was larger for younger, male and non-spousal carers. The largest single effect (training the person with dementia) rests on 10 observations and the authors call it promising rather than definitive.

Digital psychological interventions reduced caregiver burden and improved self-efficacy and quality of life; the effect on depressive symptoms was not statistically significant (P = .06).

Direction is for the test's accuracy against the reference standard; an accuracy result, not a health outcome. Pooled sensitivity 76% and specificity 83% for dementia, with 73% / 84% in primary care; the authors call it a practical screening tool while noting high or unclear risk of bias in patient selection and timing.

Direction is for a healthier plant-based diet: higher overall and healthful plant-based diet scores were associated with lower dementia risk, while a higher unhealthful plant-based diet score was associated with higher risk (pooled HR 1.42).

Pooled observational studies only.

Observational. Points the opposite way to the randomised MIND diet trial.

Observational. Points the opposite way to the randomised MIND diet trial.

Pooled observational studies only.

Dietary intake and blood levels, pooled from observational cohorts. The much larger supplement estimate (HR 0.36) comes from one cohort's self-selected supplement users, not from a trial.

The authors call the association weak (RR 0.97), and it was absent beyond 10 years of follow-up.

Pooled across 29 cohorts. The association weakened to HR 0.85 after maximal confounder adjustment and was not significant for low-intensity activity.

The authors state the association held in longer follow-ups, which is their answer to the reverse-causation objection raised by the Whitehall II cohort.

Pools 27 small trials in people who already have dementia, and reports a much larger effect (SMD 0.69) than the single largest such trial, DAPA, which found none.

Seven small trials; working memory did not improve (P=0.14).

Mostly observational (25 of 31 studies), so people who take up hearing aids may differ from those who do not. The authors call for randomised trials — and ACHIEVE, the trial that followed, was null overall.

Against untreated cataract. People who had surgery ended up at about the same risk as controls who never had cataracts (HR 0.84, 95% CI 0.66-1.06), and there was no short-term gain in those already cognitively impaired.

Pooled observational studies, so open to the confounding the natural-experiment studies were designed to avoid.

Individual participant data from five double-blind placebo-controlled trials, which is the strongest design in this table for this exposure.

Consistent across 14 trials (I-squared 0%) but small in absolute terms: 0.39 percentage points over about 4 years.

Heterogeneity was near-total (I-squared 98.9%) and the estimate went to null in people newly diagnosed with diabetes (HR 1.01), which is where prevalent-user bias would be smallest.

Education and job complexity each contributed independently; about 28% of the education effect ran through occupation.

Effect held over and above measured Alzheimer's pathology, which is the point of the reserve idea.

Improves depressive symptoms (moderate certainty) and overall behavioural problems (low certainty). No effect on agitation (SMD -0.05, 95% CI -0.27 to 0.17) and no evidence of long-term effects. Sits against the null MIDDEL trial on the same exposure.