P1‐132: INFLUENCE OF <i>BDNF</i> VAL66MET POLYMORPHISM ON HIPPOCAMPAL SUBFIELDS: MET CARRIERS DISPLAY GREATER SUBICULUM VOLUMES

Current evidence supports the involvement of brain-derived neurotrophic factor (BDNF) Val66Met polymorphisms in psychiatric and neurodegenerative disorders, including Alzheimer disease (AD) [1]. Previous studies of the association of this genotype with whole hippocampal volume included patients of a variety of disorders [2-3]. However, the impact of BDNF Val66Met polymorphisms on the volumes of the hippocampal subfields in cognitively unimpaired individuals remains to be elucidated. Therefore, the aim of the present study is to evaluate the impact of Val66Met polymorphism on hippocampal subfield volumes in cognitively unimpaired participants. BDNF Val66Met polymorphisms were determined in a sample of 430 cognitively unimpaired late/middle-aged participants from the ALFA (ALzheimer & FAmilies study [4]). Participants underwent a brain 3D-T1-weighted MRI scan and volumes of the hippocampal subfields were determined using Freesurfer (v6.0). The dominant, recessive, codominant and additive effects of the Val66Met genotype on the hippocampal subfield volumes were assessed using general linear models corrected by age, gender, education, number of APOE-e4 alleles and total intracranial volume. We additionally evaluated whether the association between age and hippocampal subfields was modified by BDNF Val66Met genotypes. p-values below 0.05 (FDR-corrected) were considered as statistically significant. Characteristics of the study participants, and differences in hippocampal subfield volumes between Val66Met genotypes are shown in Table 1 and Figure 1, respectively. Association analysis revealed that BDNF Met carriers showed statistically significant larger bilateral volumes of the subiculum under dominant and additive models (bd =20.5, pd=0.003; ba = 19.4, pa = 0.013) [Tables 2-3]. No significant results after FDR-correction were found under recessive and codominant models [Tables 4-5]. Furthermore, subfield volume reductions with aging were not significantly moderated by the Val66Met status.