October 12, 2016
By Marilynn Larkin
NEW YORK (Reuters Health) - Orthostatic hypotension (OH) is associated with an increased risk of dementia of all types, researchers say.
"Orthostatic hypotension is a widespread phenomenon in clinics and among the general population. It has been known for a while to increase risk of cardiovascular disease and stroke, but remained underinvestigated in relation to dementia," Dr. Frank J. Wolters and Dr. M. Arfan Ikram, both of Erasmus Medical Centre in Rotterdam, the Netherlands, told Reuters Health.
To investigate, Dr. Wolters, Dr. Ikram and colleagues evaluated 6,204 men and women (average age, 68.5 at baseline) without a history of stroke or dementia between 1989 and 1993. Those who experienced a drop of more than 20 mm Hg in systolic blood pressure (SBP) or 10 mm Hg in diastolic pressure within three minutes of standing from a resting position were classified as having OH.
As reported in PLoS Medicine, online October 1, during a mean follow-up of 15.3 years, 19% developed dementia, of whom 79.5% were diagnosed with Alzheimer's disease and 8.1% with vascular dementia.
After adjusting for numerous factors, including age, smoking alcohol use, medications, and APOE genotype, the researchers found that OH was associated with an increased risk of dementia (adjusted hazard ratio 1.15), which was similar for both types.
Greater SBP variability with postural change also was associated with an increased risk of dementia (aHR per standard deviation increase, 1.08), regardless of whether patients had a formal diagnosis of OH.
The authors noted that dementia risk was greatest for those with OH who lacked a compensatory increase in heart rate (aHR,1.39 for those within the lowest quartile of heart rate response).
"We found that orthostatic hypotension increases risk of dementia by 15%," Drs. Wolters and Ikram said by email. "Importantly, this was similar for symptomatic and asymptomatic blood pressure drops, suggesting that formal assessment is necessary to diagnose orthostatic hypotension in clinics, and determine whether patients require corresponding changes in medication."
"We also found that consequences of orthostatic hypotension are most profound when there is no compensatory increase in heart rate, which, if validated in future studies, may allow more specific diagnosis in clinical practice," they said.
The coauthors conclude, "Underlying mechanisms for blood pressure regulation and the impact of different medications warrant further study if we are to understand and better prevent associated diseases such as stroke and dementia."
Dr. Heather Snyder, senior director of medical and scientific operations for the Alzheimer's Association, told Reuters Health by email, "This is a solid population study of good size and duration that contributes to the literature linking cardiovascular disease with risk for later life dementia. However, this is only an association, not a cause."
"Nonetheless," she concluded, "the article is one of a great number of signals from research about the importance of maintaining and monitoring one's heart health - for overall health and for brain health as we age."
PLoS Med 2016.
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