(HealthDay News) – Onset of dementia symptoms is delayed in people who are bilingual, even among those who are illiterate, according to a study published online Nov. 6 in Neurology.

Suvarna Alladi, DM, from Nizam’s Institute of Medical Sciences in Hyderabad, India, and colleagues reviewed case records from 648 patients with dementia (391 of them bilingual) diagnosed in a specialist clinic, and compared the age at onset of first symptoms between the groups.

The researchers found that, compared with monolingual patients, bilingual patients developed dementia 4.5 years later. A significant difference in age at onset was seen for Alzheimer’s disease dementia, fronotemporal dementia, and vascular dementia; this difference was also seen in illiterate patients. Speaking more than two languages provided no additional benefit. The benefit of being bilingual was independent of other potential confounding factors such as education, sex, occupation, and urban vs. rural dwelling of subjects.

“This is the largest study so far documenting a delayed onset of dementia in bilingual patients and the first one to show it separately in different dementia subtypes,” the authors write.

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