Association of Alzheimer's disease polygenic risk scores with amyloid accumulation in cognitively intact older adults.

BACKGROUND: Early detection of individuals at risk for Alzheimer's disease (AD) is highly important. Amyloid accumulation is an early pathological AD event, but the genetic association with known AD risk variants beyond the APOE4 effect is largely unknown. We investigated the association between different AD polygenic risk scores (PRS) and amyloid accumulation in the Flemish Prevent AD Cohort KU Leuven (F-PACK). METHODS: We calculated PRS with and without the APOE region in 90 cognitively healthy F-PACK participants (baseline age 67.8 (52-80) years, 41 APOE4 carriers), with baseline and follow-up amyloid-PET (time interval 6.1 (3.4-10.9) years). Individuals were genotyped using Illumina GSA and imputed. PRS were calculated using three p-value thresholds (pT) for variant inclusion: 5 × 10-8, 1 × 10-5, and 0.1, based on the stage 1 summary statistics from Kunkle et al. (Nat Genet 51:414-30, 2019). Linear regression models determined if these PRS predicted amyloid accumulation. RESULTS: A score based on PRS excluding the APOE region at pT = 5 × 10-8 plus the weighted sum of the two major APOE variants (rs429358 and rs7412) was significantly associated with amyloid accumulation (p = 0.0126). The two major APOE variants were also significantly associated with amyloid accumulation (p = 0.0496). The other PRS were not significant. CONCLUSIONS: Specific PRS are associated with amyloid accumulation in the asymptomatic phase of AD.

Lack of association between bridging integrator 1 (BIN1) rs744373 polymorphism and tau-PET load in cognitively intact older adults.

INTRODUCTION: The bridging integrator 1(BIN1) rs744373 risk polymorphism has been linked to increased [18F]AV1451 signal in non-demented older adults (ie., mild cognitive impairment [MCI] plus cognitively normal [CN] individuals). However, the association of BIN1 with in vivo tau, amyloid beta (Aß) burden, and cognitive impairment in the asymptomatic stage of Alzheimer's disease (AD) remains unknown. METHODS: The BIN1 effect on [18F]AV1451 binding was evaluated in 59 cognitively normal (CN) participants (39% apolipoprotein E [APOE ε4]) from the Flemish Prevent AD Cohort KU Leuven (F-PACK), as well as in 66 Alzheimer's Disease Neuroimaging Initiative (ADNI) CN participants, using voxelwise and regional statistics. For comparison, 52 MCI patients from ADNI were also studied. RESULTS: Forty-four percent of F-PACK participants were BIN1 rs744373 risk-allele carriers, 21% showed high amyloid burden, and 8% had elevated [18F]AV1451 binding. In ADNI, 53% and 50% of CNs and MCIs, respectively, carried the BIN1 rs744373 risk-allele. Amyloid positivity was present in 23% of CNs and 51% of MCIs, whereas 2% of CNs and 35% of MCIs showed elevated [18F]AV1451 binding. There was no significant effect of BIN1 on voxelwise or regional [18F]AV1451 in F-PACK or ADNI CNs, or in the pooled CN sample. No significant association between BIN1 and [18F]AV1451 was obtained in ADNI MCI patients. However, in the MCI group, numerically higher [18F]AV1451 binding was observed in the BIN1 risk-allele group compared to the BIN1 normal group in regions corresponding to more progressed tau pathology. DISCUSSION: We could not confirm the association between BIN1 rs744373 risk-allele and elevated [18F]AV1451 signal in CN older adults or MCI. Numerically higher [18F]AV1451 binding was observed, however, in the MCI BIN1 risk-allele group, indicating that the previously reported positive effect may be confounded by group. Therefore, when studying how the BIN1 risk polymorphism influences AD pathogenesis, a distinction should be made between asymptomatic, MCI, and dementia stages of AD.