Prevalence of preclinical Alzheimer's disease among young adults: The Gipuzkoa Alzheimer Project study

Abstract

letter (FAS) and semantic (fruits, animals) verbal fluency tests, Digit Span Test, Stroop Color-Word Interference Test, Boston Naming Test, Rule shift cards of BADS, DEX and VOSP. The genetic study consisted of three SNPs in PICALM (rs3851179), CLU (rs11136000) and CR1 (rs3818361) gene. Genotypingwas performed through Taqman 5 ’ nuclease Assays.Results: Several associations were found between these genes and cognitive tasks. In the PICALM analysis, those carrying the GG combination (vs AA+AG) performed worse on FAS-F (GG: 7.664.6; AA+AG: 9.364; p1⁄40.027) and FAS-A (GG: 7 64.5; AA+AG: 8.664.3; p1⁄40.05). For the CLU polymorphism, patients who carried the protective TT genotype (vs CC+CT) showed a better performance on TMT-B time (TT: 168.6691; CC+CT: 244.66112.7; p1⁄40.023), on FAS-A (TT: 1165.1; CC+CT: 7.564.3; p1⁄40.012) and on backwards digit span (TT: 5.361.8; CC+CT: 3.961.3; p1⁄40.021). Finally, for the CR1 gene, MCI subjects who carried the TT genotype (VS CC+CT) got lower scores in the semantic fluency task, both in fruits (TT: 764.2; CC+CT: 10.463.1; p1⁄40.029) and animals (TT: 11.560.6; CC+CT: 13.164.3; p1⁄40.023) sections. Conclusions: There is a gene-cognitive endophenotype association between PICALM, CLU and CR1 genes in patients with MCI, being PICAL and CLU associated with prefrontal dysfunction (executive functioning) and CR1 with frontotemporal lobe dysfunction (executive functioning and semantic memory).