Midlife smoking, diabetes, and hypertension associated with late life dementia

1. Based on results of the Atherosclerotic Risk in Communities (ARIC) prospective cohort, midlife vascular risk factors associated with dementia included smoking, diabetes, prehypertension, and hypertension.

2. Other risk factors associated with dementia included black race, older age, lower educational attainment, and APOE ε4 genotype.

Evidence Rating Level: 2 (Good)

Study Rundown: Vascular dementia is a common cause of cognitive decline in the elderly, thus control of vascular risk factors may decrease the prevalence of this disease. It is unknown how much vascular risk factors present in midlife contribute to late life risk of cognitive decline. This study examined data from the Atherosclerosis Risk in Communities (ARIC) cohort to explore associations between midlife vascular risk factors and 25-year dementia incidence.

Patient characteristics associated with increased risk of dementia at 25-years was black race, older age, lower educational attainment and APOE ε4 genotype. Midlife vascular risk factors associated with higher risk of dementia included smoking, diabetes, prehypertension, and hypertension. Strengths of this study included long-follow up time to measure outcomes. However, this study did not evaluate any effect of intervention on these midlife vascular risk factors, which warrants further study.

Click to read the study, published in JAMA Neurology

Relevant Reading: Midlife cardiovascular risk factors and risk of dementia in late life

In-Depth [prospective cohort]: This large-scale prospective cohort study was conducted using patient data from the Atherosclerosis Risk in Communities Study (1987-1989) and included healthy adults aged 44 to 66 years old. The exposure of interest included midlife vascular risk factors measured at baseline: obesity, smoking, diabetes, prehypertension, hypertension, hypercholesterolemia and APOE ε4 genotype. The outcome of interest was diagnosis of dementia after 25 years of follow-up as determined by detailed neurocognitive battery of tests, interviews, and adjudicated review. Statistical analysis included adjusted Cox proportional hazards regression.

Of 15 744 participants, 1516 cases of dementia were identified over the follow-up period. Patient characteristics associated with dementia were: black race (HR 1.36; 95%CI 1.21-1.54), older age 60-66 years (HR 8.06; 95%CI 6.69-9.72), lower educational attainment less than high school education (HR 1.61; 95%CI 1.28-2.03), and APOE ε4 genotype (HR1.98; 95%CI 1.78-2.21). Midlife vascular factors associated with dementia were: smoking (HR 1.41; 95%CI 1.23-1.61), diabetes (HR 1.77; 95%CI 1.53-2.04), prehypertension (HR 1.31; 95%CI 1.14-1.51) and hypertension (HR 1.39; 95%CI 1.22-1.59).

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