Midlife Hypertension and Dementia

    

Hypertension is associated with increased risk of both Vascular dementia and Alzheimer’s disease. It’s unclear exactly how hypertension leads to dementia. The presumption is that hypertension causes hardening of the blood vessels in the brain known as atherosclerosis. This damages the blood vessels and leads to development of strokes.

 

This overly simplified explanation cannot be the only reason, as many individuals with Alzheimer’s disease don’t have evidence of strokes on their brain scans. It may be the interaction of hypertension with other risk factors such as diabetes mellitus, genetic factors, or lifestyle) that makes it a major risk for dementia.

 

In the past three decades the incidence of dementia has actually decreased.[1] One possible reason for the decrease is the increased emphasis on treating hypertension aggressively during this period. Several long-term observational studies showed significant reduction in the incidence of dementia in routinely treated versus untreated hypertension patients.[2] This reduction is seen only in those treated in mid-life rather than in the elderly.[3] For example, a double-blind study in Europe (Syst-Eur) enrolled over 3000 individuals with hypertension (i.e. Systolic blood pressure above 160) and randomly placed them either into active hypertension treatment or placebo.[4] The study was terminated early as the results from the study indicated a reduction of dementia by 55% in the treatment arm.

 

The long-term use of antihypertensive treatments decreased the incidence of both Vascular dementia and Alzheimer’s disease. Although the evidence for aggressively treating high blood pressure is compelling, not all studies showed the same results. There are many variables in clinical research that could impact the outcomes of a study. These may include factors like the age of the patients enrolled, the duration of blood pressure treatment, the duration of the follow up period, and the type of blood pressure treatment used.

 

In addition, the benefit of lowering blood pressure must be weighed against the risk of harmful effects from medications. In light of the overall benefit in keeping the systolic blood pressure in control to prevent stroke, heart attack, and dementia, the guidelines changed in 2017. It is now recommended that individuals should be treated both for stage 1 (Blood Pressure of 130-139/80-89) and stage 2 (Blood Pressure of 140/90 and greater) hypertension. Blood pressure is measured by taking at least 2 readings on 2 separate occasions and averaging the results.[5] 

A healthy diet has also been shown to reduce hypertension.  Refer to Healthy Diets for more information.

 

 

[1] Saitzabal CL, Beiser AS, Chouraki V., et.al., Incidence of dementia over three decades in the Framingham Heart Study. New England Journal of Medicine 2016; 374:523-532.

[2] In’t Veld BA, Ruitenberg A, Hofman A, Stricker BH, Breteler MM. Antihypertensive drugs and incidence of dementia: The Rotterdam Study. Neurobiol. Aging 2001; 22:407-412.

[3] Prince MJ, bird AS, Blizard RA, Mann AH. Is the cognitive function of older patients affected by antihypertensive treatment? Results from 54 months of the Medical Research Council’s treatment trial of hypertension in older adults. BMJ 1996; 312:801-805.

[4] Forette F, Seux ML, Staessen J, Lutgard T et.al., The prevention of dementia with antihypertensive treatment. New evidence from the systolic hypertension in Europe (Syst-Eur) Study. Arch Intern Med 2002;162:

[5] Whelton PK, Carey RM, Aronow WS, et.al., 2017 ACC/AHA guidelines for the prevention, detection, evaluation, and management of high blood pressure in adults.  https://doi.org/10.1161/HYP.0000000000000065.Hypertension.

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