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Antidepressants trigger an early clinical presentation of REM sleep behavior disorder: the jury is still out.

1393 Letter to the Editor—Kolla and Mansukhani In their interesting prospective cohort study addressing an important clinical issue, Postuma1 et al. evaluate the relationship between antidepressant use and idiopathic rapid eye movement sleep behavior disorder (iRBD). Their cohort comprises 100 patients who present to a sleep clinic and are found to have iRBD. After comparing patients with iRBD who are on antidepressants with healthy controls as well as other patients with iRBD who are not on antidepressants, the authors conclude that “antidepressants primarily trigger early clinical presentation of an RBD that is nonetheless still due to underlying neurodegeneration.” The authors posit that because the patients in their cohort with antidepressant-associated RBD had markers for neurodegeneration and lower rates of developing neurodegenerative disorders, antidepressants primarily trigger an early clinical presentation caused by an underlying degenerative disorder. Based on the current data, we believe that this conclusion may be premature. In the introduction, the authors acknowledge that antidepressant use could be a proxy marker for depression, a prodromal symptom for neurodegeneration. This possibility is discounted in the discussion because patients with antidepressant-associated iRBD had lower rates of developing neurodegeneration at the end of the study period. Depression can predate neurodegeneration by many years.2,3 The study population was followed for 8 y, and patients with a possible temporal relationship between antidepressant use and iRBD were significantly younger than the no-antidepressant group (62.0 ± 10.9 versus 67.8 ± 9.7; P = 0.03; Table S1); if the antidepressant group were followed for a longer duration, neurodegeneration could possibly develop at similar rates. Thus, the possibility that antidepressant use is a proxy measure of depression remains a viable explanation. Additionally, this study relies on subject recall to determine the relationship between antidepressant use and the onset of iRBD. This is prone to recall bias and hence the temporal relationship between the onset of iRBD, and antidepressant use is not certain. Also, the authors state that iRBD was diagnosed based on either polysomnography (PSG) findings or clinical LETTER TO THE EDITOR