Cardiovascular health reduces dementia risk

Aiming to keep systolic pressure at or below 120mmHg is associated with a lower risk of mild cognitive impairment and dementia compared with a target of 140mmHg, according to a new analysis of the Systolic Blood Pressure Intervention Trial (SPRINT).

SPRINT has already shown that intensive blood pressure control reduces cardiovascular morbidity and mortality (N Engl J Med 2015;373:2103–16). SPRINT-MIND, a new analysis presented at the Alzheimer’s Association International Conference 2018 in Chicago, involved 9361 older people (mean age 68 years) with hypertension and increased cardiovascular risk but without diagnosed diabetes, dementia or prior stroke. First-line treatment was predominantly with a thiazide-type diuretic, a loop diuretic for people with kidney disease or a beta-blocker for those with coronary artery disease. At one year, mean systolic pressure was 121.4mmHg in the intensive treatment group and 136.2mmHg in the standard treatment group.

The trial was ended after a median follow-up of approximately three years because of the reduction in cardiovascular risk but cognitive assessment continued for up to another three years. Intensive blood pressure treatment was associated with a 19% reduction in the incidence of new-onset mild cognitive impairment and a 15% reduction in mild cognitive impairment and probable dementia combined; both differences were statistically significant. A sub-study showed that intensive treatment was associated with a smaller increase in white matter lesions in the brain; these are associated with an increased risk of stroke, dementia and death.

Announcement of the SPRINT-MIND results coincides with publication of a French study which examined the link between cardiovascular health in older people (n=6626, mean age 74 years) and the risk of dementia (JAMA 2018;320:657–64). Cardiovascular health was defined according to the American Heart Association’s seven health metrics (not smoking, eating fish at least twice a week, eating fruit and vegetables at least three times a day, body mass index <25, and low untreated levels of cholesterol, blood glucose and blood pressure). After a mean follow-up of 8.5 years, 745 diagnoses of dementia were confirmed. The risk of dementia decreased with every additional marker of cardiovascular health, from 1.76 per 100 person-years with no or one health metric to 0.8 per 100 person-years in people with all seven, and this was associated with lower rates of cognitive decline.

Data from the Royal College of General Practitioners Research and Surveillance Centre have provided a picture of cardiovascular health in England (BMJ Open 2018;8:e020282). The analysis involved nearly 1.3 million adults, of whom 271,684 had cardiovascular disease or hypertension. Current smoking was less prevalent in people with cardiovascular disease or hypertension than those without these conditions (14% vs 20%), though there were more ex-smokers in the former group (54% vs 29%). Excess alcohol use was more frequent in those with cardiovascular disease or hypertension (42% vs 24%) and mean BMI was greater (42 vs 26). Hypertension was the most common cardiovascular disorder (18%) followed by coronary artery disease (3.5%) and atrial fibrillation (2.7%). Over half of people with cardiovascular disorders were prescribed at least one of the three most common cardiovascular medications (an ACE inhibitor, a statin or a calcium-channel blocker).

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