Associations between NIH‐Toolbox Flanker test and the Picture Sequence Memory Test and multimodal Alzheimer’s disease biomarkers in cognitively unimpaired individuals

Abstract

AbstractBackgroundAlzheimer’s disease (AD) pathologic changes start years before cognitive symptoms appear; however, some early cognitive changes can be detected. We aimed to investigate the association between performance changes in two NIH‐Toolbox tests, Flanker test and Picture Sequence Memory Test (PSMT), and baseline AD biomarkers in cognitively unimpaired (CU) individuals.MethodWe studied 356 ALFA+ participants (mean [SD] age = 60.8 [4.72] years). The rate of cognitive change after 3 years was measured through delta scores (Follow‐up ‐ Baseline). Biomarker data included cerebrospinal fluid (CSF) β‐amyloid (Aβ) 42/40 ratio, phosphorylated‐tau‐181 (p‐tau), neurofilament light (NfL), and neuroimaging (MRI‐based cortical thickness AD signature, hippocampal volumes, and FDG‐PET‐SUVR (fluorodeoxyglucose ‐ positron emission tomography ‐ standardized uptake value ratio) metaROI) measures (Table 1). CSF Aβ40, Aβ42 and NfL were measured with the exploratory NTK robust immunoassays, while CSF p‐tau181 was measured using the electrochemiluminescence Elecsys® Phospho‐Tau (181P) CSF immunoassays (Roche Diagnostics International Ltd). AT groups were defined according to published cut‐offs (A+ Aβ 42/40 <0.071; T+: p‐tau > 24 pg/ml) (Milà‐Alomà et al., 2020). Baseline biomarker levels were used as predictors of cognitive change in linear models. Interactions and stratified analyses were also explored.ResultAT groups significantly differed in the change in the Flanker Test (p = 0.002), driven by poorer performance in A+T+ vs A‐T‐ groups (p = 0.001) (Figure1). Higher cortical thickness predicted better longitudinal cognitive performance in the Flanker Test in the whole group (p = 0.020; β = 0.983). We found a significant interaction between AT group and FDG‐PET‐SUVR (p = 0.042), and the right hippocampal volume (p = 0.001), but no significant associations were observed in analyses stratified by AT (Figure2A). A negative association between right hippocampal volume and Flanker test change was observed in A+T‐ (p = 0.026) and A+T+ (p = 0.029) (Figure2B). No associations were observed between the PSMT and AD biomarkers (Figure 1).ConclusionOur findings support the hypothesis that executive function show a steeper decline than episodic memory in CU individuals with evidence of pathologic AD biomarkers levels. We observed a negative association between executive change and neuroimaging neurodegeneration markers in A+T‐ and A+T+ groups. This is in accordance with previous studies that found non‐linear associations in incipient AD pathology.