Treatment Initiation and Outcomes Associated With Receipt of Emergency Department-Based Peer Support Following Opioid Overdose.

A reduced sense of smell is one of the most frequent and earliest non-motor symptoms in Parkinson's disease (PD). While hyposmia can be detected five to ten years prior to the first motor symptoms, it is still unknown whether and, if so, to what extent olfactory function declines with disease progression. Most cross-sectional studies on olfactory function in PD patients, using either the University of Pennsylvania Smell Identification Test (UPSIT) or the Sniffin’ Sticks smell screening test, found no evidence for a time-dependent decline. However, two studies reported a negative correlation between disease duration and UPSIT scores. One study reported a similar correlation between disease duration and scores on the Sniffin’ Sticks odor discrimination, but not odor identification, test. Recently, in a cross-sectional study in 295 PD patients, we found hyposmia to be associated with various motor and non-motor symptoms, including cognitive deficits, depression, anxiety, autonomic dysfunction, and sleep disturbances. To date, only a limited number of PD studies have examined olfactory function longitudinally over the course of the disease. In the extant studies, follow-up periods were relatively short, various olfactory tests were employed, and sample sizes were typically small. No significant decrease in UPSIT scores over a two-year period was found in one study of 24 PD patients. In another study, a small, yet similar, decrease in UPSIT scores was noted in both 25 PD patients and 24 healthy controls over the course of a 45-month follow-up period. In three small-scale longitudinal studies using Sniffin’ Sticks, olfactory function of PD patients changed in an unpredictable way; some patients improved whereas others worsened. Taken together, previous cross-sectional and longitudinal studies failed to establish whether PD-related olfactory dysfunction is a stable disease feature or worsens with increasing disease duration.