Correlation of Antidepressant Use and Symptom Time Period in Dream Enactment Behaviors

概要

It is with great interest that we read the article by Otaiku that investigated the effects of dream content on future symptom exacerbation.1 In line with their study, we would like to highlight three concerns.

　First, the incidence of dream enactment behaviors (DEBs) due to antidepressant intake should be considered. Antidepressants have been reported to cause DEBs.2 Considering that patients with Parkinson's disease (PD) are commonly comorbid with depression, the PD with aggressive dreams group in this study may include patients with DEBs caused by antidepressants, suggesting that depression comorbidity may be a confounding factor. Although according to the article, "all patients were at an early stage and unmedicated at baseline," neither the study nor the Parkinson's Progression Marker Initiative database describes the rate of depression or the use of antidepressants. It would be helpful to specify the antidepressants use to resolve this concern.

　Second, clonazepam use may lead to cognitive decline. Otaiku reported that in patients in the PD with aggressive dreams group, cognitive function was significantly impaired. Since patients with rapid eye movement (REM) sleep behavior disorder (RBD) are often injured, it is necessary and appropriate to start medications to relieve DEBs to prevent injury. However, clonazepam, commonly used in DEB treatment, cause sedative side effects and impair cognitive function.3 The author could address the impact of medications on cognitive impairment by describing the use of DEB treatment at baseline and follow-up.

　Third, the fluctuation in the symptoms of DEBs in PD patients was not considered. DEBs in patients with idiopathic RBD or PD with RBD may diminish over time. Our previous study found that in patients with idiopathic RBD, the frequency of DEBs peaked 2–8 years after RBD onset and decreased afterwards.4 Moreover, it was reported that RBD symptoms improved after three years of follow-up in a quarter of PD patients with RBD.5 The DEBs seem to exacerbate for a while and then lessen in intensity, rather than worsen over time. Therefore, when assessing the dream experience of patients with PD, there are three possible situations: those who never had aggressive dreams; those currently experiencing aggressive dreams; those who previously experienced aggressive dreams but are not currently experiencing them. In the RBD screening questionnaire (RBDSQ), the period of aggressive dream experience is not defined (e.g., the last six months). Therefore, patients who answered "No" to item 3 of the RBDSQ, stating that "My dreams frequently have an aggressive or action- packed content," may include those who never experienced aggressive dreams before, and those who once experienced aggressive dreams but now no longer do. It remains to be determined whether the group whose aggressive dreams have disappeared should be included in the "without aggressive dreams" group or indicated separately. However, it is essential to clarify the time frame in the survey and obtain information on previous symptom occurrences. The proportion of those who have never experienced aggressive dreams before or whose aggressive dreams have disappeared in the PD without aggressive dreams group should be described.