SLC6A3 and major depressive disorder: In PARS, participants with hyposmia were more likely to report altered mood (anxiety and depression), RBD symptoms, and constipation.18 In those who went on to have dopamine transporter imaging, hyposmia, male gender, and constipation combined effectively to predict dopaminergic deficit.5 In the TREND study, which recruited based on the presence of 1 or more of depression, RBD, and anosmia, the clustering of prodromal features was also observed.21