These findings provide additional support for the links between fast beta EEG and alcohol use problems. Taken further, this may suggest that 3q26 harbors variants that are related to both fast beta EEG and alcohol problems (or underlying externalizing behavior, for example, ADHD). In addition, this could suggest that fast beta EEG may mediate the associations between 3q26 and alcohol problems. To assess this, post hoc we examined the association between 3q26 variants and fast beta EEG, adjusted for AD. Results (Supplementary Figure S3A) show that the 3q26 association remains but is slightly diminished, suggesting that AD may have an indirect role in the association of 3q26 and fast beta EEG in this sample. Stated another way, fast beta EEG may be a risk factor for some, but not all individuals with AD. These findings, along with the ADHD findings, could also indicate that the association between 3q26 and fast beta EEG is more reflective of generalized neural disinhibition, best captured in this sample by ADHD as compared with CoD and AD. Future studies are needed to examine these hypotheses.
