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and risk of Alzheimer disease
Overview
High cholesterol, high blood pressure, and diabetes at mid-life all increase the chances of both cardiovascular and Alzheimer disease years later. While links between the heart and the brain remain unclear, factors like hypertension are attractive from a prevention perspective because they can be modified with effective therapeutic interventions and lifestyle modifications. Indeed, several studies have raised the hypothesis that anti-hypertensive medications might reduce the incidence of dementia such as Alzheimer's Diseae (AD).
A new epidemiological study finds that the use of a specific class of anti-hypertensive drug medication known as the angiotensin receptor blockers (ARBs) is associated with a lower incidence of AD, fewer nursing home admissions, and fewer deaths compared to other treatments for hypertension. The results suggest that ARBs are more effective at forestalling dementia than other blood pressure medications, including angiotensin converting enzyme (ACE) inhibitors.
ACE inhibitors were previously associated with slowing of cognitive decline in older adults with hypertension (Sink et al., 2009). This new study indicates that the combination of ARBs and ACE inhibitors display additive effects.
Although ARBs and ACE inhibitors interfere with the angiotensin II peptide, they act in different ways. ACE inhibitors prevent production of the active peptide, while ARBs antagonize the type 1 angiotensin II receptor.
To compare the effects of different medications, the authors analyzed information on heart patients divided into three groups: those who took any angiotensin receptor blockers, those who took the ACE inhibitor lisinopril, and those who used other cardiovascular drugs.
Compared to patients taking the ACE inhibitor or other cardiovascular drugs, veterans who had taken ARBs had a 16 to 24 percent lower risk of developing AD or dementia four years later.
Li and coworkers looked also at nursing home admissions and death. Among ARB users, the researchers saw a 50 percent reduction in nursing home admissions compared to the cardiovascular comparator group, and a 17 percent reduction in deaths. Lisinopril use was also associated with a reduction in dementia incidence and nursing home admissions, but to a lesser degree than the ARBs. Compared to ACE inhibitor use alone, combination treatment gave a 55
Another paper published by researchers at the Women's Health Initiative found that women with high blood pressure at baseline and those with poorly controlled high blood pressure had the most white matter lesions. They conclude that tight control of blood pressure levels, especially beginning at younger and middle age, may be the only way to prevent dementia.
A report published in Stroke describes a prospective clinical study on the impact of medication and lifestyle changes in the progression of white matter lesions in patients with AD. In the study, 65 patients with early AD and cerebrovascular lesions were randomized to standard care or a special regimen of vascular care. This included lifestyle interventions (weight loss, improved diet, more exercise, ending smoking), treatment of hypertension with drugs other than ACE inhibitors or ARBs, and of hypercholesterolemia where present, and a supplement of aspirin, pyridoxine, and folic acid. After two years, a follow-up MRI showed that the white matter lesions of the vascular care group had progressed less. The investigators conclude that while the intervention was successful in slowing the progress of brain lesions, efforts may need to start even earlier to be clinically meaningful.
References
Li NC et al. Use of angiotensin receptor blockers and risk of dementia in a predominantly male population: prospective cohort analysis. BMJ. 2010 Jan 12;340:b5465.
Click here to read the article.
Kuller LH et al. Relationship of Hypertension, Blood Pressure, and Blood Pressure Control With White Matter Abnormalities in the Women's Health Initiative Memory Study (WHIMS)-MRI Trial. The Journal of Clinical Hypertension. December 2009
Richard E et al. Vascular Care in Patients With Alzheimer Disease With Cerebrovascular Lesions Slows Progression of White Matter Lesions on MRI. The Evaluation of Vascular Care in Alzheimer's Disease (EVA) Study. Stroke. 2010 Jan 7.
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