Bilingualism May Offer Defence Against Age-Related Cognitive Decline
In a groundbreaking study published in Nature, researchers have revealed an intriguing link between bilingualism, brain structure, and social cognition. Led by Xiaoqian Li and her team, the study investigates the correlation between the age at which individuals acquire a second language (L2AoA) and their ability to understand the thoughts and beliefs of others, known as theory of mind (ToM).
The research, involving bilingual adults across different age groups, sheds light on the potential protective effects of bilingualism against cognitive decline, especially in the domain of social cognitive functioning. Participants underwent a series of tests to evaluate their ToM abilities, completed language background questionnaires, and underwent anatomical MRI scans to examine cortical morphometric features, including grey matter volume, thickness, and surface area.
The study’s findings unveiled several key insights. Firstly, there was a noticeable decline in ToM performance among older adults compared to their younger counterparts, even after adjusting for factors such as education and general cognition. This decline underscores the well-documented age-related changes in ToM abilities.
However, the most significant discovery lies in the associations between brain structure, L2AoA, and ToM performance. Participants who acquired their second language earlier in life exhibited larger grey matter volume, higher cortical thickness, and larger surface area in specific brain regions linked to mental representations, language processing, and cognitive control. Crucially, these structural differences correlated with better ToM performance, suggesting that early bilingual acquisition may offer protective benefits against age-related declines in social cognitive abilities.
Furthermore, the study observed that the relationship between brain structure and ToM was particularly pronounced in older adults, indicating that bilingualism may exert a stronger influence on social cognitive processes as individuals age. This finding aligns with theories of neural reserve, proposing that early-life experiences, such as bilingualism, may bolster brain resilience and safeguard against cognitive decline in later years.
This research provides compelling evidence for the profound impact of bilingualism on brain structure and social cognition throughout life. The paper titled ‘Brain gray matter morphometry relates to onset age of bilingualism and theory of mind in young and older adults’ is published in Nature Scientific Reports.
