High blood pressure linked to cognitive impairment

High blood pressure linked to cognitive impairment

US researchers examining nearly 20,000 people aged 45 and over found that those with high diastolic blood pressure were more likely to have cognitive impairment, where thinking and memory ability is reduced, than people with normal diastolic pressure.

The study was the work of first author Dr Georgios Tsivgoulis, of the University of Alabama at Birmingham, and colleagues, and is published in the 25 August print issue of Neurology.

Diastolic pressure is measured when the heart is relaxed, it is usually the second and lower reading of two measures taken for blood pressure, the other being systolic, taken when the heart is contracting.

For the study, Tsivgoulis and colleagues examined records from nearly 20,000 participants aged 45 and over who were taking part in the Reasons for Geographic And Racial Differences in Stroke (REGARDS) Study. None of the participants had had a stroke or mini-stroke.

1,505 (7.6 per cent) of the participants were found to have cognitive impairment, and 9,844 (49.6 per cent) were taking medication for high blood pressure.

The researchers found that the odds of having cognitive impairment was 7 per cent higher for every 10 points of increase in diastolic pressure.

The link was still there after taking into account possible influencers like age, smoking, physical activity, education, diabetes and cholesterol.

The researchers concluded that:

"Higher diastolic blood pressure was cross-sectionally and independently associated with impaired cognitive status in this large, geographically dispersed, race- and sex-balanced sample of stroke-free individuals."

Tsivgoulis told the press that while more research was needed to confirm the link between high blood pressure and cognitive impairment:

"It's possible that by preventing or treating high blood pressure, we could potentially prevent cognitive impairment, which can be a precursor to dementia."

While this study has not proved high blood pressure actually causes cognitive impairment, it seems plausible that it does because other studies have found that high diastolic blood pressure weakens the small arteries in the brain, which can lead to small areas of the brain being damaged by loss of blood.

The National Institute of Neurological Disorders and Stroke (NINDS) funded the study.

"Association of higher diastolic blood pressure levels with cognitive impairment."

G. Tsivgoulis, A. V. Alexandrov, V. G. Wadley, F. W. Unverzagt, R.C.P. Go, C. S. Moy, B. Kissela, and G. Howard.

Neurology, 25 Aug 2009; 73: 589 - 595.

Additional sources: AAN.

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Section Issues On Medicine: Cardiology