Hypertension and Atrial Fibrillation Increase Cognitive Decline in Alzheimer's Disease


Explain to interested patients that certain vascular risk factors are associated with an increased rate of cognitive decline in patients who have been diagnosed with Alzheimer's disease.
Point out that treatment of hypertension was associated with less cognitive decline.
Uncontrolled high blood pressure doubled the rate of memory loss compared with patients who had normal blood pressure, Michele M. Mielke, Ph.D., of Johns Hopkins, and colleagues, reported in the Nov. 6 issue of Neurology. Atrial fibrillation.was associated with a 75% increase in memory loss.
"The possibility that specific vascular conditions may affect how fast a person with Alzheimer's disease declines provides new opportunities for slowing the rate of Alzheimer's disease progression," said Dr. Mielke. "Treatment of atrial fibrillation and high blood pressure are relatively inexpensive and safe and may reduce memory decline in Alzheimer's disease patients with these conditions."
Longitudinal studies have shown that vascular risk factors, including hypertension and atrial fibrillation, also are risk factors for Alzheimer's disease, the authors noted. However, the effect of vascular risk factors on progression of established Alzheimer's disease had not been determined. Three previous studies yielded inconsistent results, but two of the three suggested an association between vascular risk factors and progression of Alzheimer's disease.
To continue the evaluation, Dr. Mielke and colleagues studied 135 patients ages 65 and older with Alzheimer's. They were followed by in-home visits for an average of three years. Scales of dementia status and cognitive function were administered at each home visit.
The investigators found that 51 of the patients had none of the vascular risk factors assessed (atrial fibrillation, hypertension, angina, coronary bypass surgery, myocardial infarction, stroke, diabetes, and antihypertensive therapy). A third of the patients had one risk factor, 18.5% had two, and 10.4% had three or more vascular risk factors.
Considering all the risk factors in a vascular index, Dr. Mielke and colleagues found no association between the index and the rate of cognitive decline. Among the individual risk factors, atrial fibrillation and hypertension (defined as systolic blood pressure >160 mm Hg) remained independent predictors of more rapid decline in cognitive function (P0.001 for both).
Angina also predicted more rapid decline in cognitive function (P0.05), but the authors said the finding was not unexpected, given the association of Alzheimer's disease and angina with atherosclerotic vascular disease.
Antihypertensive therapy, coronary bypass surgery, and diabetes were all associated with less decline in cognitive function. The protective effect of bypass surgery came as a surprise, given the procedure's association with cognitive impairment and dementia, the authors noted. The protective effect of diabetes seems counterintuitive, they continued, but other studies have shown that diabetes does not increase the risk of Alzheimer's.
As for the protective effect of antihypertensives, the authors said, "Antihypertensive medications have been reported to decrease the risk of Alzheimer's disease onset. Our findings further suggest that these medications may also be important in slowing progression once a person is diagnosed with Alzheimer's disease."
The authors disclosed no conflicts of interest.
Primary source: NeurologySource reference: Mielke MM, et al "Vascular factors predict rate of progression in Alzhkeimer disease"Neurology 2007; 69: 1850-1858.