For the lower alpha band, the BD group showed overall strong, rather than reduced, connectivity compared with the non-BD group. In terms of the upper alpha band, the BD group exhibited increased connectivity in the prefrontal-posterior parietal area. This is consistent with the results of Winterer et al. (2003), who reported increased alpha connectivity in patients with AUDs. Along with increased connectivity in the theta band, the increased connectivity in the lower and upper alpha bands may be a compensatory mechanism in response to damage in certain areas or altered connections (Coullaut-Valera et al., 2014; Correas et al., 2015).
