• ageing;
  • dementia;
  • preventive medicine;
  • public health;
  • risk factors



This study investigated the association between perceived physical fitness at midlife, changes in perceived fitness during the three decades from mid- to late life and dementia risk.


Prospective cohort study.


Cardiovascular risk factors, ageing and incidence of dementia (CAIDE) study.


Subjects were selected from four independent, random samples of population-based cardiovascular surveys and were first examined in 1972, 1977, 1982 or 1987, when they were on average 50 years old. The CAIDE target population included 3559 individuals. A random sample of 2000 individuals still alive in 1997 was drawn for re-examinations (performed in 1998 and 2005–2008) that consisted of cognitive assessments, with 1511 subjects participating in at least one re-examination. Dementia diagnoses were also confirmed from national registers for the entire target population.

Main outcome measure

All-cause dementia.


Poor physical fitness at midlife was associated with increased dementia risk in the entire target population [hazard ratio (HR), 1.5; 95% confidence interval (CI), 1.1–2.0]. In participants, odds ratio (OR) was 2.0 (95% CI, 0.9–4.0). This association was significant in apolipoprotein E ε4 allele (APOEε4) noncarriers (OR, 4.3; 95% CI, 1.4–13.3), men (HR, 1.8; 95% CI, 1.1–3.0) and people with chronic conditions (HR, 2.9; 95% CI, 1.3–6.6). A decline in fitness after midlife was also associated with dementia (OR, 3.0; 95% CI, 1.7–5.1), which was significant amongst both men and women and more pronounced in APOEε4 carriers (OR, 4.4; 95% CI, 2.1–9.1).


Perceived poor physical fitness reflects a combination of biological and lifestyle-related factors that can increase dementia risk. A simple question about perceived physical fitness may reveal at-risk individuals who could benefit from preventive interventions.