Stroke Rounds: Bilingual Brains Sustain Less Stroke Damage by Salynn BoylesContributing Writer This article is a collaboration between MedPage Today® and: Medpage Today Speaking more than one language might protect against cognitive injury related to stroke, according to findings from an Indian registry study. Compared to patients who spoke only one language, bilingual stroke patients were more than twice as likely to have normal cognition following their stroke and they also performed better on tests measuring post-stroke attention and function. But the two groups had similar frequencies of aphasia, at 11.8% among monolinguals and 10.5% among bilinguals (P=0.354), which might be explained by a higher level of cognitive control in patients speaking two or more languages, Suvarna Alladi, DM, of Nizam's Institute of Medical Sciences in Hyderabad, India, and colleagues wrote online in Stroke. "The only outcome not influenced by bilingualism was the frequency of aphasia," the researchers wrote. "Although this might look surprising at first sight, this finding is in-line with current research, suggesting that the mechanism underlying the protective effect of bilingualism is not because of better linguistic but executive functions acquired through a lifelong practice of language switching." 'Intriguing, But Not Conclusive' Jose Biller, MD, chair of the Loyola University department of neurology, which lists him as trilingual, told MedPage Today that another recently published, small (n=174 patient) study from the U.K. showed bilingual stroke patients to have poorer post-stroke language skills. Biller, who is also a spokesman for the American Stroke Association, was not involved with either study. "There is a great deal of interest in the impact of bilingualism on cognitive aging and now stroke outcomes," he said. "But it is important to be cautious in interpreting findings. These are small studies, and while the findings are intriguing, they are far from conclusive." Several previous studies have suggested that bilingualism might protect against Alzheimer's disease and general age-related cognitive decline, but little is known about the impact of bilingualism, if any, on cognitive outcomes in stroke, the researchers wrote. The study included ischemic stroke patients enrolled in a stroke registry in Hyderabad, India, who were evaluated 3 to 24 months after their strokes during the study period from 2006 to 2013. The evaluations included a detailed history and clinical assessment conducted by behavioral neurologists, stroke specialists, and trained psychologists using a structured diagnostic protocol adapted from the Cambridge Memory Clinic Model. Of the 608 patients included in the study, 189 (31.1%) had vascular dementia and 159 (26.2%) had mild cognitive impairment. Sixty-seven (11%) had aphasia and 193 (31.7%) were determined to have normal cognitive function. Twice as many bilinguals had normal cognition compared to patients who spoke only one language (40.5% versus 19.6%, P<0.0001), and monolinguals were more likely to have vascular dementia and mild cognitive impairment (77.7% versus 49.0%, P<0.0009). Other Dementia Risk Factors Older age, lower educational and occupational status, monolingualism, and vascular risk factors were all found to be significant risk factors for post-stroke cognitive impairment (P<0.003). In an attempt to assess whether bilingualism was independently associated with post-stroke cognitive impairment, the researchers performed a series of logistic regression analyses. "These regression models demonstrated variance of 31%, 24% and 28%, respectively," the researchers wrote. "Significant variables from the analyses were entered into a final logistic regression analysis. Following a Bonferroni correction, bilingualism and age were found to be significant independent predictors." The study participants came from Hyderabad, India, where several languages are routinely spoken, including Hindi, English, Telugu, and Urdu. Because of this, the researchers noted that the findings may not be applicable to bilingual people who live in areas like the U.S., where it is common to speak only one language. "Bilingualism is the norm in many parts of the world," Biller said. "We know from previous research that bilingualism induces certain plastic changes in the brain. However, the functional significance of these changes remains the subject of debate."
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