Torres Solano, Valeria Lucia

Controversy surrounds the idea that bilingualism leads to enhanced executive function (EF) and brain volume changes, potentially leading to delays in cognitive decline and dementia onset. The purpose of this research was to explore these claims in a sample of elderly monolinguals and bilinguals. This study explored gray matter volume (GMV) in 214 monolinguals and bilinguals (Mage = 71.21, SD = 7.53) who were cognitively normal (CN) or diagnosed with Mild Cognitive Impairment (MCI) or dementia. Neuropsychological performance was also examined between CN and MCI monolinguals and bilinguals (N = 153) across two visits. Scores from the Digit Span Backwards, Stroop interference, Trail Making Test A minus Trail Making Test B, and category fluency average scores were used. Magnetic Resonance Imaging (MRI) brain regions associated with memory, language, and EF were selected. Additionally, the study examined how a Bilingualism Index (BI) and the age of acquisition of English could predict GMV and EF in Spanish/English bilinguals whose native language was Spanish.
Lastly, the initial age of cognitive decline across language groups was compared. Results suggested higher GMV in language and EF regions in bilinguals, but differences were not found in memory regions. Furthermore, neuropsychological performance over time did not vary across language groups; however, bilinguals exhibited reduced Stroop interference as well as lower scores on Digit Span Backwards and category fluency. The age of acquisition of English did not predict GMV or EF scores, while the BI predicted category fluency, with lower scores associated with a higher degree of balanced bilingualism. Overall, the influence of bilingualism appears to be reflected in increased GMV in specific language and EF regions relative to neuropsychological performance.

The types of intrusion errors (Prior List, Semantically Related, and Unrelated)
made on the LASSI-L verbal memory task were compared across three diagnostic groups
(N = 160, 61 % female), Cognitively Normal (CN), amnestic Mild Cognitive Impairment
(aMCI), and Alzheimer’s disease (AD). Errors related to Proactive, Recovery from
Proactive, and Retroactive Interference were also analyzed, as well as the relationship of
errors to Amyloid load, a biomarker of AD. Results suggest that the types of error made
indicated the level of cognitive decline. It appears that as deficits increase, impaired
semantic networks result in the simultaneous activation of items that are semantically
related to LASSI-L words. In the aMCI group, providing a semantic cue resulted in an
increased production of Semantically Related intrusions. Unrelated intrusions occurred
rarely, although, a small number occurred even in the CN group, warranting further
investigation. Amyloid load correlated with all intrusion errors.