Zusammenfassung
Bilingualism can delay the onset of dementia symptoms and has
thus been characterized as a mechanism for cognitive or brain
reserve, although the origin of this reserve is unknown. Studies
with young adults generally show that bilingualism is associated
with a strengthening of white matter, but there is conflicting
evidence for how bilingualism affects white matter in older age.
Given that bilingualism has been shown to help stave off the
symptoms of dementia by up to four years, it is crucial that we
clarify the mechanism underlying this reserve. The current study
uses diffusion tensor imaging (DTI) to compare monolinguals and
bilinguals while carefully controlling for potential confounds
(e.g., I.Q., MMSE, and demographic variables). We show that
group differences in Fractional Anisotropy (FA) and Radial
Diffusivity (RD) arise from multivariable interactions not
adequately controlled for by sequential bivariate testing. After
matching and statistically controlling for confounds, bilinguals
still had greater axial diffusivity (AD) in the left superior
longitudinal fasciculus than monolingual peers, supporting a
neural reserve account for healthy older bilinguals.
Nutzer