BALTIMORE—The impact of blood pressure on the risk of dementia in late life follows a U-shaped curve in which elevated mid-life and late-life blood pressure, as well as late-life decline in blood pressure, all independently increase the risk of dementia, according to findings from a longitudinal study of the Framingham Offspring cohort of the Framingham Heart Study.
The findings highlight the benefits of establishing and maintaining lower blood pressure in mid-life for preventing or decreasing the risk of dementia, said Emer McGrath, MD, a neurology resident at Massachusetts General Hospital in Boston, at the 141st Annual Meeting of the American Neurological Association.
Hypertension has been linked to stroke and dementia and is the most important modifiable risk factor for both outcomes. Likewise, elevated blood pressure in mid-life (ie, ages 40 to 64) and late life (ie, age 65 or older) has been linked with a heightened risk of cognitive decline, as has low blood pressure in late life, but “the relationship between blood pressure in mid and late life and dementia [is] less clear, and the relationship of blood pressure changes from mid to late life is unknown,” said Dr. McGrath.
The researchers explored the issue using data from the Framingham Offspring cohort of the Framingham Heart Study. The cohort comprises 5,124 children and spouses of children of the original Framingham cohort. They have been examined clinically at regular intervals since 1971. The present study focused on 1,440 individuals who had five consecutive examinations during a 15-year period anytime between 1983 and 2001 and who had not been diagnosed with dementia at the time of the final blood pressure determination.
The 1,440 participants had a mean age of 69 at their fifth examination. Slightly more than half were female, 20% had been diagnosed with cardiovascular disease, and slightly less than 20% had been diagnosed with diabetes. Half were using antihypertensive medications.
During a mean eight-year follow-up period, 107 individuals developed dementia. Dementia was independently associated with mid-life hypertension (ie, blood pressure of 140/90 mm Hg or higher), with a stronger association for systolic hypertension (hazard ratio [HR], 1.57). Persistence of hypertension into late life, particularly systolic hypertension (HR, 1.96), was another independent risk factor for dementia.
Among individuals who did not have hypertension at mid-life, a decline in systolic blood pressure to less than 100/70 mm Hg in the ensuing years increased the risk of dementia (HR, 1.63).
The findings support the hypothesis of the U-shaped relationship between blood pressure and dementia, according to the researchers. “Our data also highlight the potential sustained cognitive benefits of lower mid-life blood pressure,” said Dr. McGrath.
The study was funded by the Framingham Heart Study, the National Institute on Aging, and the National Institute for Neurological Diseases and Stroke.
McDonald C, Pearce MS, Kerr SR, Newton JL. Blood pressure variability and cognitive decline in older people: a 5-year longitudinal study. J Hypertens. 2016 Sep 17 [Epub ahead of print].