Control of High Blood Pressure May Be Key to Treatment of Mixed Dementia
]]>Dementia]]> , characterized by confusion, memory loss, and the inability to perform normal daily activities, affects an estimated 6.8 million people in the United States.
]]>Alzheimer’s disease]]> is the best known dementia, but emerging research shows that as many as one in four patients with dementia has a combination of Alzheimer’s disease and vascular dementia. This combination is known as mixed dementia .
Vascular dementia results from a series of small ]]>strokes]]> that impair blood flow to the brain. Does that mean that controlling the risk factors for stroke, or more broadly, cardiovascular disease, could have benefits for the brain?
In a scientific literature review published in the December 15, 2004 Journal of the American Medicine Association , researchers examined the effects of both Alzheimer’s medications and cardiovascular drugs on people with mixed dementia severe enough to prevent them from functioning independently in daily life. They found that treating cardiovascular risk factors, particularly ]]>high blood pressure]]> , had significant benefits for patients with mixed dementia. Alzheimer’s medications had similar effects on people with mixed dementia as they did on people with only Alzheimer’s disease.
About the Study
The researchers identified English-language articles published within the last ten years that looked at mixed dementia, Alzheimer’s disease, cerebrovascular disorders, vascular dementia, and related drug therapies. For their review of drug treatments for mixed dementia, the scientists focused on randomized, double-blind, placebo-controlled trials—considered to be the highest-quality type of study. They supplemented their research with additional, less rigorous, studies.
High Blood Pressure Medications : A number of observational studies showed a link between high blood pressure and cognitive decline, and a protective effect of blood pressure lowering drugs on dementia. One randomized, controlled trial found a significant decrease in the incidence of dementia over a four-year period in hypertensive patients taking a blood pressure medication called a calcium channel blocker, compared to those who were not taking this medication.
Cholesterol-Lowering Medications (Statins) : Though observational studies showed a link between elevated cholesterol at middle age and cognitive decline, no randomized, controlled trials confirmed that cholesterol-lowering medications reduced the risk of mixed dementia.
The researchers looked at the cholinesterase inhibitors galantamine (Reminyl), rivastigmine (Exelon), and donepezil (Aricept), as well as memantine, which is from a new class of drugs used to treat Alzheimer’s. They found that overall, these drugs were about as effective in patients with mixed dementia as they are in patients with Alzheimer’s disease. The cholinesterase inhibitors, for example, provided the equivalent of a 4–6 month delay in cognitive decline.
However, as in patients with Alzheimer’s disease, the response to the medications was highly variable. In the studies, 30% to 50% of the mixed dementia patients showed no response to the cholinesterase inhibitors, while about 20% had a greater than average response.
None of the studies showed beneficial effects of aspirin, vitamin E, or ginkgo biloba on mixed dementia.
How Does This Affect You?
This review has many implications for the treatment of mixed dementia. Perhaps most importantly, it demonstrates the link between cardiovascular health and mental function. The studies examined in this review showed that medically controlling high blood pressure decreased the incidence of dementia.
Though the randomized, controlled trials cited here did not examine the effects of lifestyle-controlled hypertension on mixed dementia, it would be reasonable for patients with mixed dementia to implement blood pressure lowering lifestyle changes—low-salt, high calcium diet and increased physical activity, for example—to slow or prevent cognitive decline.
Alzheimer’s medications had a similar effect in people with mixed dementia as they do in people with Alzheimer’s disease. That’s good news; though unfortunately, up to 50% of patients show no improvement from these medications. Physicians should discuss this uneven response with patients and caregivers before deciding whether to begin treatment. They should also do a follow up within the first few months of treatment to determine whether these costly drugs are having a measurable effect.
Even if Alzheimer’s medications effectively slow the pace of worsening dementia, they have no effect on other serious conditions faced by elderly patients. The benefits of controlling cardiovascular risk factors, on the other hand, help to preserve not only the mind, but the body as well.
National Institute of Neurological Disorders and Stroke
National Institutes of Health
National Institute on Aging
National Institutes of Health
Langa KM et al. Mixed dementia: emerging concepts and therapeutic implications. Journal of the American Medical Association . 2004; 292(23): 2901–2908.
Last reviewed Dec 17, 2004 by ]]>Richard Glickman-Simon, MD]]>
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