Although there have been previous studies that have linked raised blood pressure in midlife to an increased risk of dementia in later life, the term ‘midlife’ has been poorly defined and ranged from 35 to 68 years.
In the Whitehall II study, participants aged 35-55 in 1985, had their blood pressure measured in 1985, 1991, 1997 and 2003. Other medical information was also taken, such as age, sex, lifestyle behaviors (such as smoking and alcohol intake), and socio-demographic factors.
- Among the 8,639 people analyzed for this study, 32.5% of whom were women, 385 developed dementia by 2017.
- Those who had a systolic blood pressure of 130 mmHg or more at the age of 50 had a 45% greater risk of developing dementia than those with a lower systolic blood pressure at the same age.
- This association was not seen at the ages of 60 and 70, and diastolic blood pressure was not linked to dementia.
- The link between high blood pressure and dementia was also seen in people who had no heart or blood vessel-related conditions (cardiovascular disease) during the follow-up period; they had an increased risk of 47% compared to people with systolic blood pressure lower than 130 mm.
Professor Singh-Manoux, said: “Our work confirms the detrimental effects of midlife hypertension for risk of dementia, as suggested by previous research. It also suggests that at age 50, the risk of dementia may be increased in people who have raised levels of systolic blood pressure below the threshold commonly used to treat hypertension.
“Our analysis suggests that the importance of mid-life hypertension on brain health is due to the duration of exposure. So we see an increased risk for people with raised blood pressure at age 50, but not 60 or 70, because those with hypertension at age 50 are likely to be ‘exposed’ to this risk for longer.” The average age at which the study participants developed dementia was 75.
Possible reasons for the link between raised blood pressure and dementia include the fact that high blood pressure is linked to silent or mini-strokes (where symptoms often are not noticeable), damage to the white matter in the brain, which contains many of the brain’s nerve fibers, and restricted blood supply to the brain. This damage may underlie the resulting decline in the brain’s processes.
Dr. Jessica Abell, a post-doctoral research fellow at INSERM said: “It is important to emphasize that this is observational, population-level research and so these findings do not translate directly into implications for individual patients. Furthermore, there is considerable discussion on the optimal threshold for the diagnosis of hypertension. There is plenty of evidence to suggest that maintaining a healthy blood pressure in middle age is important for both your heart and your brain later in life. Anyone who is concerned about their blood pressure levels should consult their GP.”
“One of the strengths of this study was having repeat blood pressure measurements on the same people, which allowed us to examine their blood pressure status over an 18-year period. This is rare since previous research has often used a single measure of hypertension,” concluded Professor Singh-Manoux.
Based on the study, the authors concluded that systolic blood pressure ≥130 mmHg at age 50, below the conventional ≥140 mmHg threshold used to define hypertension, is associated with increased risk of dementia; in these persons, this excess risk is independent of CVD.
For more information click on the link: https://doi.org/10.1093/eurheartj/ehy288
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