Objectives: Spoken bilingualism may be associated with cognitive reserve. Mastering a complicated written language may be associated with additional reserve. We sought to determine if midlife use of spoken and written Japanese was associated with lower rates of late life cognitive decline.
Methods: Participants were second-generation Japanese-American men from the Hawaiian island of Oahu, born 1900-1919, free of dementia in 1991, and categorized based on midlife self-reported use of spoken and written Japanese (total n included in primary analysis = 2,520). Cognitive functioning was measured with the Cognitive Abilities Screening Instrument scored using item response theory. We used mixed effects models, controlling for age, income, education, smoking status, apolipoprotein E e4 alleles, and number of study visits.
Results: Rates of cognitive decline were not related to use of spoken or written Japanese. This finding was consistent across numerous sensitivity analyses.
Discussion: We did not find evidence to support the hypothesis that multilingualism is associated with cognitive reserve.