Disruption of the serial position effect as an early marker of Alzheimer’s disease in Spanish–English bilinguals

Abstract

Objectives: The present study examined if disruption of serial position effects in list recall could serve as an early marker of Alzheimer’s disease (AD) in Spanish–English bilinguals. Methods: We tested 20 participants initially diagnosed as cognitively normal or with mild cognitive impairment who declined and eventually received a diagnosis of AD (decliners), and 37 who remained cognitively stable (controls) over at least 2 years. Participants were tested on the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) Word List Learning Test in English or Spanish as part of an annual neuropsychological evaluation. Results: Compared to controls, decliners exhibited significantly reduced recall including reduced primacy scores (i.e., items recalled from the first three list items on Trial 1), whereas recency scores (i.e., items recalled from the last 3 list items on Trial 1) were equivalent in decliners and controls. Further analyses suggested that the sensitivity of the primacy effect to preclinical AD was initially stronger in participants tested in Spanish, a surprising finding given that the CERAD was developed for English speakers. However, in the subsequent year of testing, primacy scores declined to the same level regardless of language of testing. Conclusions: Several list learning measures may facilitate early diagnosis of AD in Spanish–English bilinguals, possibly including the relatively understudied primacy effect. Additional studies are needed to investigate the possibility that linguistic or demographic variables might modulate sensitivity of list learning tests to preclinical AD, which could lead to broader improvements in their utility for early diagnosis of AD in all populations.

Language switching and speaking a nondominant language challenge executive control: Preliminary data for novel behavioral markers of Alzheimer’s risk in Spanish–English bilinguals.

“…Given the relatively small number of participants, these results must be viewed as strictly preliminary and exploratory 6 . Though we did not find the sensitivity of memory measures in the present study (see Table 2), in other recent work with participants drawn from the same population list, memory measures were sensitive to future decline with a shorter lag between testing and time of diagnosis (Mizrahi et al, 2023). Additional work is needed to determine the trajectory of decline of different cognitive abilities in Spanish–English bilinguals at risk for AD.…”