The Austrian Stroke Prevention Study (ASPS) recently reported associations between aging, smoking and body mass index (BMI) with gray matter T2* in 314 participants (38-82 years)38, likely reflecting iron accumulation in local tissue13. We sought to replicate several of their key findings as a demonstration of a hypothesis-led investigation. The ASPS study reported R2*, which is the reciprocal of the T2* value we estimate in UK Biobank; therefore we expected T2* associations with opposite sign to those reported by ASPS. The main results from ASPS in deep gray matter structures were as follows: BMI was the strongest determinant of R2* generally, and was significantly related to R2* in amygdala (beta=0.23, PFDR=0.009) and hippocampus (beta=0.14, PFDR<0.0001). Further associations with R2* (averaged across subcortical structures) were found for age (beta=0.03, PFDR =0.027) and recent smoking level (beta=0.02, PFDR=0.001). No equivalent associations were found for sex or hypertension. The ASPS conducted univariate correlations and multiple regressions to identify both shared and unique variance in the associations, using FDR correction. Based on these results, we hypothesize negative association between T2* in subcortical structures with BMI, age and smoking.
