Table 1

PA and all-cause dementia: main results, main sensitivity analyses with meta-regressions and subgroup analyses, and dose–response analysis

Pooled RR95% CII2 (%)Studies combined (n)Beta estimate*95% CI
All physical activity0.800.77 to 0.8468.749
Baseline age (continuous)1.000.98 to 1.02
Baseline age (categorical)
Age group 30–55 years9 33 35 36 39 40 42 55 61 62 66 73 77 800.790.71 to 0.8742.914
Age group 55–69 years44 45 57 58 81 830.820.74 to 0.9070.86
Age group ≥70 years11 32 34 37 38 41 43 46–54 56 59 60 63–65 72 74–76 79 820.800.75 to 0.8570.429
Follow-up length (continuous)1.000.97 to 1.03
Follow-up length (categorical)
Follow-up length <5 years38 43 46 51 52 54 63 75 78 790.610.50 to 0.7464.810
Follow-up length 5–20 years9 11 32 34 37 41 44 45 47–50 56–59 64 65 72 74 76 81–830.860.82 to 0.9064.224
Follow-up length ≥20 years9 33 35 36 39 40 42 53 55 60–62 66 73 77 800.790.71 to 0.8744.816
Study quality (high vs moderate vs low)†0.990.64 to 1.53
Low quality9 11 32 34 35 38 41 43–47 49–51 56–58 60 62–66 72 74–76 78 79 81 830.810.77 to 0.8575.532
Moderate quality9 33 36 37 39 42 48 52–54 59 73 77 80 820.790.72 to 0.8628.415
High quality9 40 55 610.820.67 to 0.9958.94
Meeting PA guidelines‡ 11 33 36 38 43 44 48 53–55 59–61 63 65 72 73 76 80 830.820.76 to 0.8722.020
Not meeting PA guidelines‡ 9 11 32 33 36 38 44 45 47–49 51 57 58 61 62 65 66 72–75 77–79 830.760.69 to 0.8360.825
Highest quality studies only: age group 30–55 years, follow-up length >20 years and high quality40 55 610.790.62 to 1.0167.43
  • *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.

  • †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=0.202).

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