Bilingualism's effects on resting-state functional connectivity in mild cognitive impairment

Background: Bilingualism is considered a cognitive reserve (CR) factor, due to the delay in the onset of dementia in bilinguals compared with monolinguals. Two neural mechanisms have been suggested to underlie CR: neural reserve and neural compensation. However, it is still unclear how bilingualism contributes to these mechanisms.Methods: In this study, we used cognitive tests, functional connectivity (FC), regional homogeneity, and fractional amplitude of low-frequency fluctuations (fALFF) measures to study resting-state brain patterns in a sample of bilingual and monolingual subjects with mild cognitive impairment. Results: We found no significant differences between the groups in age, sex, education, or cognitive level, but bilinguals showed higher FC than monolinguals between the posterior part of the superior temporal gyrus and the precuneus, positively correlated with Mini-Mental State Examination scores, and higher fALFF in the thalamus bilaterally. Conclusions: Our results suggest that bilingualism may act as a CR factor that protects against dementia through neural compensation. ; This work was supported by the project (201410-30-31) provided by Fundació Marató TV3. L. M-M., N. A. and J. A-V. were supported by an FPU grant from the Spanish Ministry of Education, Culture and Sports, and E. V-R., by an FPU grant from the Ministry of Science, Innovation and Universities. M-Á. P-G. and A. M-P. were supported by a postdoctoral graduate program grant (University Jaume I) and V.C. was supported by a Juan de la Cierva post-doctoral graduate program grant from the Spanish Ministry of Economy, Industry and Competitiveness (IJCI-2016-29247).