Repurposing verbal fluency: Word‐property analysis reveals neurocognitive markers of Hispanics with Alzheimer’s disease and mild cognitive impairment

Abstract

AbstractBackgroundThough central to dementia assessments, verbal fluency tasks are suboptimally exploited. Performance is typically measured by counting valid responses. This precludes insights on which word types are least accessible to patients, while failing to discriminate among disorders. Alternatively, each word can be decomposed into relevant properties that drive semantic memory retrievability. Recently, our team has combined objective lexical measures with multimodal imaging to examine whether this approach is sensitive to Hispanics with Alzheimer’s disease (AD) and mild cognitive impairment (MCI), vis‐à‐vis others with behavioral variant frontotemporal dementia (bvFTD).MethodIn Experiment‐1, we recruited 32 AD patients and 32 bvFTD patients, matched with 27 HCs. Experiment‐2 involved 60 persons with MCI and 60 matched HCs. Participants performed phonemic and semantic fluency tasks. We counted valid responses and, using normative databases, extracted quantitative data of six word properties: frequency (occurrences in everyday use), granularity (conceptual specificity), neighborhood (words with similar phonological structure), length (number of syllables), familiarity (subjective recognizability), and imageability (ease of mental visualization). We examined whether these variables were robust to discriminate between groups (via ANOVAs), identify individuals from each cohort (via linear regressions), and capture cognitive, neuroanatomical, and functional connectivity disruptions.ResultsIn Experiment‐1, while both patient groups produced fewer valid responses than HCs, only AD patients showed distinct word properties (higher frequency, lower granularity, more phonological neighbors). Multivariate word properties robustly identified individual AD (but not bvFTD) patients from HCs (AUC = .89), driven by the abovementioned properties. These features correlated with executive outcomes only in AD, and they predicted patients’ anatomical and functional disruptions along temporal, frontal, and cingulate regions. In Experiment‐2, the same word properties differentiated MCI individuals from HCs, with multivariate classification reaching an AUC of .75. These features correlated with the volume of, and connectivity between, temporal and frontal regions that partly overlapped with those observed in AD.ConclusionVerbal fluency tasks can be repurposed to reveal condition‐specific markers of persons with and at increased risk for AD. New avenues emerge towards scalable, low‐cost assessment of Hispanics and, potentially, other underrepresented populations.