Cognitive and brain reserve in bilingual speakers with clinical AD variants
Nicoletta Biondo, John Matthew Suntay, Maria Luisa Mandelli, Muskaan Sandhu, Jeanine Sandra Estaban, Janhavi Pillai, Eugenie Mamuyac, Rochelle‐Jan Reyes, Ariel Guevarra, Maya L. Henry, Nina F. Dronkers, Maria Luisa Gorno‐Tempini, Stephanie M. Grasso, Jessica de LeonAbstract
INTRODUCTION
Bilingualism may confer resilience through enhanced neural integrity. However, evidence for its neuroprotective effect is mixed, and studies across Alzheimer's disease (AD) variants are limited. This study examined gray matter volume (GMV) differences between bilinguals and monolinguals with amnestic AD and logopenic variant primary progressive aphasia (lvPPA).
METHODS
In 125 amnestic AD and 78 lvPPA participants with neuropsychological assessments and structural magnetic resonance imaging, we analyzed GMV differences between monolinguals and bilinguals within each variant, adjusting for demographic covariates.
RESULTS
In amnestic AD, bilinguals showed lower GMV than monolinguals in several regions, including bilateral fusiform and right occipital regions, after correction for multiple comparisons. In lvPPA, regional differences did not survive correction for multiple comparisons, although at the nominal threshold, bilinguals showed lower GMV in temporal and occipital regions and greater GMV in inferior parietal regions. Cognitive performance was comparable between monolinguals and bilinguals within each group.
DISCUSSION
Comparable cognitive performance despite lower GMV is consistent with a potential role of bilingualism in cognitive reserve. The observed regional patterns in lvPPA are exploratory and require replication in a larger sample.