A study conducted in India has provided even stronger evidence that speaking a second language may protect against dementia. Published online in early November in Neurology, the study from Nizam’s Institute of Medical Sciences in Hyderabad, India, has produced the most concrete evidence of this connection yet.
Two previous studies conducted in Toronto, Canada, have suggested that bilingualism might postpone dementia but the participants of those studies were immigrants with very different cultural backgrounds than members of the monolingual group, which introduced a high degree of confounding to the data. Thomas H. Bak, MD, from the University of Edinburgh, who is co-author of this new study, explained that they chose Hyderabad, India for the study because “it has large numbers of both monolingual and bilingual people, and it is a native population with few immigrants,” making it an ideal location.
The Effects of Bilingualism on Instances of Dementia
The study focused on 648 patients with dementia diagnosed at a specialist clinic, 391 of whom were bilingual. The age of onset was compared between monolingual and bilingual groups. The results showed that, overall, bilingual patients developed dementia four and a half years later than those who spoke only a single language. That was consistent across the different types of dementia and was also independent of other confounding factors like education, gender, occupation, and urban vs. rural dwelling. Dr. Bak noted that the results were “stunningly similar to those from the Canadian studies,” which strongly suggests that bilingualism is the key to this effect, not location, education, or cultural background.
- For more information and detailed reporting on the study, visit www. medscape.com.
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