Table 2.

PA and Alzheimer’s disease: main results, main sensitivity analyses with meta-regressions and subgroup analyses, and dose–response analysis

	Pooled RR	95% CI	I2 (%)	Cohorts combined (n)	Beta estimate*	95% CI
All PA	0.86	0.80 to 0.93	47.6	24
Baseline age (continuous)					1.00	0.97 to 1.03
Baseline age (categorical)
Age group 30–55 years9 12 33 40 77 80	0.81	0.66 to 0.99	37.3	6
Age group 55–69 years† 44	1.09	0.96 to 1.24	0.0	1
Age group ≥70 years11 37 38 47 48 52 54 59 60 63 67–71 84 85	0.84	0.77 to 0.93	48.5	17
Follow-up length					1.00	0.96 to 1.04
Follow-up length <5 years38 52 54 63 70 84	0.93	0.79 to 1.08	48.4	6
Follow-up length 5–20 years9 11 37 44 47 48 59 67–69 71 85	0.87	0.78 to 0.97	41.3	12
Follow-up length ≥20 years9 12 33 40 60 77 80	0.76	0.64 to 0.90	16.9	7
Study quality (low vs moderate vs high)‡					1.14	0.59 to 2.22
Low quality9 11 44 47 60 63 67 68 70 71	0.97	0.88 to 1.07	34.1	10
Moderate quality9 33 37 38 48 52 54 59 69 77 80 84 85	0.81	0.74 to 0.90	24.0	13
High quality 9 12 40	0.71	0.42 to 1.22	71.8	3
Meeting PA guidelines§ 11 12 33 38 44 47 48 54 59 60 63 68 69 71 80 84	0.75	0.64 to 0.88	43.4	16
Not meeting PA guidelines§ 9 11 33 38 44 48 67 69 77 80	0.94	0.85 to 1.04	0.0	10
Age group 30–55 years, high quality and follow-up length >20 years12 40	0.55	0.29 to 1.03	53.9	2

*Beta estimate is the regression coefficient from the meta-regression examining the relationship of modifier or continuous PA on the log risk ratio of dementia.

†Only one study, not meta-analytical analysis.

‡Study quality was assessed with a quality assessment tool we developed (see online supplemental material part 1 for details).

§The test for heterogeneity between groups was non-significant (p=0.126).

I², heterogeneity; PA, physical activity; RR, relative risk.