Favorable Cardiovascular Health at Young and Middle Ages and Dementia in Older Age-The CHA Study

Abstract

Background Data are sparse on the association of cardiovascular health ( CVH ) in younger/middle age with the incidence of dementia later in life. Methods and Results We linked the CHA (Chicago Heart Association Detection Project in Industry) study data, assessed in 1967 to 1973, with 1991 to 2010 Medicare and National Death Index data. Favorable CVH was defined as untreated systolic blood pressure/diastolic blood pressure ≤120/≤80 mm Hg, untreated serum total cholesterol <5.18 mmol/L, not smoking, bone mass index <25 kg/m², and no diabetes mellitus. International Classification of Diseases, Ninth Revision (ICD-9) codes and claims dates were used to identify the first dementia diagnosis. Cox models were used to estimate hazard ratios of incident dementia after age 65 years by baseline CVH status. Among 10 119 participants baseline aged 23 to 47 years, 32.4% were women, 9.2% were black, and 7.3% had favorable baseline CVH . The incidence rate of dementia during follow-up after age 65 was 13.9%. After adjustment, the hazard ratio for incident dementia was lowest in those with favorable baseline CVH and increased with higher risk factor burden ( P-trend<0.001). The hazards of dementia in those with baseline favorable, moderate, and 1-only high-risk factor were lower by 31%, 26%, and 20%, respectively, compared with those with ≥2 high-risk factors. The association was attenuated but remained significant ( P-trend<0.01) when the model was further adjusted for competing risk of death. Patterns of associations were similar for men and women, and for those with a higher and lower baseline education level. Conclusions In this large population-based study, a favorable CVH profile at younger age is associated with a lower risk of dementia in older age.

Keywords: Alzheimer's disease; aging; cardiovascular disease risk factors; dementia; epidemiology.

Figure 1

Dementia status and death before dementia during 1991 to 2010 by baseline cardiovascular health status. Death before dementia: all‐cause death before the first diagnosis of any type of dementia. Favorable level of all major cardiovascular disease risk factors (blood pressure ≤120/≤80 mm Hg and no antihypertensive medication, serum cholesterol <5.18 mmol/L and no lipid‐lowering medication, not smoking, bone mass index <25 kg/m², no diabetes mellitus); Moderate‐risk: One or more unfavorable/borderline levels of untreated systolic blood pressure 121 to 139 mm Hg or diastolic blood pressure 81 to 89 mm Hg, or untreated serum total cholesterol 5.18 to 6.21 mmol/L, or BMI 25.0 to 29.9 kg/m², not smoking, no diabetes mellitus; High‐Risk: High systolic blood pressure/diastolic blood pressure (≥140/90) or using antihypertensive medication, serum total cholesterol ≥6.22 mmol/L or using lipid‐lowering medication, smoking, bone mass index ≥30.0 kg/m², diabetes mellitus. CVH indicates cardiovascular health. *P value for group comparison based on Chi‐square tests.

Figure 2

Cumulative incidence of dementia after aged 65 years during 1991 to 2010 by baseline cardiovascular health status. First diagnosis of any type of dementia. Favorable level of all major cardiovascular disease risk factors (blood pressure ≤120/≤80 mm Hg and no antihypertensive medication, serum cholesterol <5.18 mmol/L and no lipid‐lowering medication, not smoking, bone mass index <25 kg/m², no diabetes mellitus); Moderate‐risk: One or more unfavorable/borderline levels of untreated systolic blood pressure 121 to 139 mm Hg or diastolic blood pressure 81 to 89 mm Hg, or untreated serum total cholesterol 5.18 to 6.21 mmol/L, or bone mass index 25.0 to 29.9 kg/m², not smoking, no diabetes mellitus; High‐risk: high systolic blood pressure/diastolic blood pressure (≥140/90) or using antihypertensive medication, serum total cholesterol ≥6.22 mmol/L or using lipid‐lowering medication, smoking, bone mass index ≥30.0 kg/m², diabetes mellitus. *P value for the Wald test.