Early‐life bilingualism could protect from age‐related gray matter volume loss in the left caudate – preliminary results

Abstract

AbstractBackgroundEarly‐life bilingualism (i.e., second language acquisition before the age of 30) has been shown to confer benefits in separate cognitive domains later in life, possibly contributing to the concept of cognitive reserve. However, the effects of early‐life bilingualism on cognitive performance and gray matter volume (GMV) in the elderly have been studied scarcely. In an ongoing cohort, we examined the influence of early‐life bilingualism on cognitive performance (e.g., phonemic fluency as tested by the Regensburg word fluency test (RWT), among others) as well as age‐related brain gray matter volume in older adults.MethodWe analysed 3‐Tesla T1‐weighted Multi‐Echo MPRAGE and cognitive data from 25 healthy adults (72.8±7.69 years, 10 female) in our new cohort established within the CRC1436 (https://sfb1436.de/). Assessment of bilingualism was conducted using the Lifetime of Experiences Questionnaire (LEQ). MRI data were preprocessed and analysed using FSL‐VBM. We performed a whole‐brain analysis looking for an interaction between age and bilingualism on GMV values, postulating that early bilingualism might contribute to a preservation of gray matter along the age trajectory. We extracted GMV values from significant regions of interest (ROIs) and looked for correlations with cognitive performance. Due to the small cohort and the preliminary nature of these analyses, we chose an exploratory threshold of p<0.001 (uncorrected) for the whole brain analysis. ROIs were defined by a threshold of p<0.1 cluster‐corrected (z>3.1).ResultParticipants with early‐life bilingualism (n = 7) had significantly more years of education (p<0.05) and performed better in the RWT (p<0.05) than monolinguals (n = 18). The age‐bilingualism interaction term across the whole brain (adjusted for education) identified the head of left caudate nucleus as being protected from age‐related GMV loss by early‐life bilingualism (Fig. 1). The age‐GMV‐relationship for both groups is shown in Fig. 2. We observed no significant relationship between GMV in the left caudate and performance in any cognitive tests.ConclusionThese preliminary results hint at a role of early‐life bilingualism in modulating GMV in older adults. How these relate to better cognitive performance remains to be elucidated. Moreover, considering brain areas not typically studied in cognitive aging, such as the basal ganglia, seems worthwhile.