VIENNA—“One third of patients with stroke develop dementia within three months after the stroke,” according to Tom S. Olsen, MD, PhD. Dr. Olsen, Chairman of the Department of Neurology at Gentofte University Hospital, Hellerup, Denmark, and colleagues investigated the risk factors for dementia after stroke in an effort to determine the dominant factors and the extent to which they were modifiable. They found that age, stroke recurrence, and hypertension were the most significant risk factors for developing dementia following acute stroke.

A RANGE OF RISK FACTORS

Dr. Olsen reported the results of the study, drawn from a seven-year follow-up of 1,197 consecutive patients with acute stroke identified between 1991 and 1993, at the Sixth Congress of the European Federation of Neurological Societies. The study cohort was 46% male, with a mean age of 74. Presence or absence of hypertension, diabetes, ischemic heart disease, claudication, atrial fibrillation, alcohol, smoking, and comorbidity was noted.

All patients underwent a cranial computed tomography (CT) scan. The researchers assessed patients using the Scandinavian Stroke Scale (SSS), with a range of 0 to 58, and the Mini-Mental State Examination (MMSE). Patients with scores of 24 or lower on the MMSE were considered demented. The MMSE was administered at bedside immediately after admission in the acute state and again after seven years. If the patient was not able to cooperate at follow-up, he or she was excluded from the study. The mean admission SSS was 37 and the mean MMSE, 20.5. MMSE scores tended to correlate with SSS at both admission and follow-up.

RISK ANALYSES

A univariate analysis at seven-year follow-up demonstrated that several factors correlated with survival. Survivors were significantly younger (69.6 versus 77.4), had higher SSS scores (44.8 versus 30.8), were less likely to have atrial fibrillation (9% versus 23.7%), were less likely to have ischemic heart disease (16.3% versus 27.6%), and were more likely to have daily alcohol consumption. Gender or hypertension, diabetes, claudication, or daily smoking did not affect the likelihood of survival.

In a multivariate analysis, independent predictors of decline of MMSE over time were age, stroke severity, hypertension, stroke recurrence, and MMSE in the acute state, which resulted in a decline at follow-up of 6.6 points per 10 points decrease. Dr. Olsen summarized, “The older you are when you have a stroke, the higher the risk of developing dementia. In addition, if patients had a stroke recurrence during the seven-year follow-up period, they had a higher risk of developing dementia. If they had hypertension when they started, then they also had a higher risk of developing dementia.”

However, gender, atrial fibrillation, diabetes, ischemic heart disease, smoking, alcohol intake, stroke type, cohabitance, or leukoaraiosis on CT had no influence on the development of dementia, Dr. Olsen noted. “This study emphasizes the importance of secondary stroke prevention. If you have hypertension early in life, your risk of dementia later in life is much higher. That is why it is so important to treat hypertension,” he concluded.

NR

—Andrew Wilner, MD

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