Beat the Odds of Alzheimer's

Summarized by Robert W. Griffith, MD
April 10, 2006

Introduction

Reliable studies from around the world have shown that high blood pressure increases the odds of developing Alzheimer's disease. So it's not surprising that someone has examined whether antihypertensive treatment will lower these odds. A consortium of researchers used data from an ongoing study of elderly citizens in Utah to determine this point. Their findings are published in the Archives of Neurology, and we summarize them here.

What was done

In 1995 all the people over 65 living in Cache County, Utah, USA were invited to enroll in a study of elders' disease risks. They were given a standardized interview and work-up at entry, and again 3 years later. The interviews included a detailed listing of all medicines, including over-the-counter remedies, currently being taken.

Screening for dementia was done using the Modified Mini-Mental State Examination (3MS), or an equivalent questionnaire for the caregivers of those unable to participate in the 3MS. Those with dementia at the first screen were excluded from the second screen; in this way participants who developed dementia during the 3 years following enrollment were identified.

All participants were classified as antihypertensive drug users if they were currently taking any of the following class of drugs: ACE inhibitors, beta-blocking agents, calcium channel blockers, thiazide diuretics, potassium-sparing diuretics, and loop diuretics.

The analyses concentrated on determining any association between the use of antihypertensive medication at baseline and the subsequent risk of developing Alzheimer's disease.

What was found

Over 3,300 people were enrolled in this study; their average age was 74, and 58% were women. The approximately 1500 people taking antihypertensive medication were somewhat older, more often women (63%), less well educated, and more likely to have had a stroke, diabetes, heart attack, or high cholesterol, compared to those not taking these drugs.

Taking any drug to lower blood pressure was associated with a 36% reduction in the odds for developing Alzheimer's. For diuretics, the reduction was 43%; and for potassium-sparing diuretics (e.g. spironolactone, amiloride, or triamterene) the reduction was 74%. These results were obtained after making adjustments for differences in age, gender, education, and previous illness that might have biased the outcome.

What these findings mean

In this large study, there was a reduction in the odds of developing dementia in those people taking blood pressure medication. In particular, potassium-sparing diuretics (water pills) seemed to help the participants beat the odds of Alzheimer's.

The researchers suggest that the benefits seen with these medications are independent of their blood-pressure lowering effect, but the numbers of subjects are too small for them to be certain of this. The potassium-sparing diuretics exert their effect without lowering serum potassium levels, and this feature may account for their superiority; there's an unpublished study that describes increased serum potassium levels in association with reduced odds of Alzheimer's.

We must recognize that this type of study is open to the possibility of confounding - i.e. the relation of blood pressure medication use and the reduced Alzheimer's may merely reflect the association of both to another, unmeasured factor. But it's important that factors such as age, lower education, and gender - all normally linked to an increased risk of Alzheimer - were, in this study, irrelevant, as shown by the results after statistical adjustments.

The findings of the study should lead to further research into a possible protective effect of the drugs concerned. They should not, however, cause anyone to start taking one or other of these drugs, just to try to beat the odds of getting Alzheimer's disease. Rather, adjustments in lifestyle (sensible diet, exercise -including mental exercise- and plenty of social interaction) should go much further towards this goal.

Source

• Khatachaturian AS, Zandi PP, Lyketsos CG, et al. Antihypertensive medication use and incident Alzheimer disease. Arch Neurol 2006;63: doi:10.1001/archneur.63.5.noc60013 online, accessed 3/25/06

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