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Silent Stroke Affects 10 Percent of Healthy Middle-Aged Patients
| Author: Lorraine Savage |
| Article Date: 7/20/2008 |
A recent study found that 10 percent of otherwise healthy middle-aged people had had a silent stroke, or silent cerebral infarction (SCI). The study also found that presence of atrial fibrillation, a form of heart arrhythmia, increased the risk of SCI occurrences. These findings show a need for physicians to test patients for cardiovascular risk factors early in midlife
“Prevalence and Correlates of Silent Cerebral Infarcts in the Framingham Offspring Study” was published in the June 2008 issue of Stroke: Journal of the American Heart Association. SCI, which is damaged brain tissue due to interruption of blood flow, can lead to increased risk of clinical strokes and cognitive impairment and dementia.
Methodology
Participants in the study belonged to the Framingham [Massachusetts] Offspring Study, which consists of children of the participants in the Framingham Heart Study, a study begun in 1971 to track people for decades and identify risk factors for cardiovascular disease.
The recent study gathered 2040 participants of the Framingham Offspring Study, who were examined every four to eight years. Most were of European descent, 53 percent were female, median age 62. They were free of clinical stroke and considered in general good health.
Researchers performed volumetric brain MRI scans on the participants between 1999 and 2005. Researchers accounted for age-and gender-specific risk factors, and examined correlations of SCI using multivariable logistic regression models.
Findings
The study found that 10.7 percent of participants exhibited SCI. Of those with SCI, 84 percent had only one lesion. SCI generally occurred in the basal ganglia (52%), other subcortical (35%) and cortical (11%) areas.
The researchers correlated data from the Framingham Stroke Risk Profile to incidence of SCI. The most significant finding was that a history of atrial fibrillation (AF) increased the risk for SCI more than two-fold. While researchers are not concluding that AF causes SCI, they say it may just be a simultaneous outcome. Risk factors such as hypertension that may make people susceptible to AF also make them susceptible to clinical stroke and SCI. AF is the most common form of heart arrhythmia in people over the age of 65.
The study also found that risk factors known to be associated with clinical stroke were also associated with risk of SCI in midlife. In addition to hypertension and AF, risk factors for SCI were found to be elevated plasma homocysteine, carotid artery disease, and high systolic blood pressure. Age and gender did not have a significant affect on the risk factors for SCI.
Recommendations
Previous estimates of SCI occurrence based on MRI scans has been between 5.8 percent and 17.7 percent, depending on such factors as age, ethnicity, comorbidities, and imaging techniques. So this study’s findings of 10.7 percent prevalence is comparable.
As two-thirds of people over age 65 have high blood pressure, physicians are encouraged to carefully monitor patients in midlife who have high risk factors for clinical strokes and SCI. Early diagnosis and prevention of hypertension and atherosclerosis and their risk factors are imperative.