The association between Alzheimer’s disease blood‐based biomarkers and cognitive impairment and probable dementia in Look AHEAD MIND

Abstract

AbstractBackgroundThe effect of an intensive lifestyle intervention (ILI) on Alzheimer’s disease (AD) blood‐based biomarker levels and cognitive outcomes among individuals with type 2 diabetes (T2D) is unknown. We examined AD biomarkers and cognitive outcomes in the Look AHEAD Study.MethodParticipants aged 45‐76 years were randomized at baseline to a 10‐year ILI or a diabetes support and education (DSE) condition. Cognitive assessments at years 8‐18 included measures of attention, executive function, global function, and memory. Mild cognitive impairment (MCI) and probable dementia were adjudicated by an expert panel. Stored baseline and end‐of‐intervention plasma samples were analyzed with the Quanterix Simoa HD‐X Analyzer. Changes in Aβ42/Aβ40, ptau181, neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) were evaluated in relation to randomization status, demographic characteristics, and cognitive outcomes. Cognitive scores and biomarker levels were converted to z‐scores. Cognitive trajectories were evaluated using mixed models to account for repeated measures; logistic regression was used for a composite outcome of MCI/dementia. Models were adjusted for baseline characteristics (age, sex, education, race/ethnicity, body mass index (BMI), CVD history, hypertension, diabetes duration, eGFR), APOE‐ε4, randomization arm, time from randomization, and time between blood draw and cognitive testing.ResultThe mean age of 779 participants was 61.4 years; 56% = female, 22.8% = APOE ε4+, mean BMI = 34.8, baseline diabetes duration >5 years = 57%, 16.7% Black, 12.5% Hispanic, 66.2% White, and 4.7% other racial and ethnic groups. There were no associations between the intervention and biomarker levels at baseline or biomarker change over time. Increases in NfL levels significantly predicted lower memory (‐0.04 ±0.01; p = 0.002), global cognition scores (‐0.05 ±0.02; p = 0.011), executive function (‐0.04 ±0.01; p = 0.01), as well as increased risk of MCI/probable dementia (odds ratio [OR] 1.10, 95% CI 1.02‐1.19). Increases in GFAP predicted lower memory (‐0.10 ±0.03; p = 0.0001), global cognition (‐0.09 ±0.03; p = 0.009), executive function scores (‐0.12 ±0.03; p<0.0001), and increased risk of MCI/probable dementia (OR 1.24, 95% CI 1.09‐1.41).ConclusionThere was no association between the intervention and changes in biomarker levels. Increasing levels of NfL and GFAP over the ∼10 year period were associated with reduced cognitive performance and increased risk of MCI/probable dementia.