Depression and Anxiety in Persons with Parkinson's Disease With and Without “On–Off” Phenomena
Abstract“On–off” phenomena in Parkinson's disease (PD) are unpredictable motor fluctuations associated with long-term levodopa use. Mood fluctuations have been found to coincide with the motor fluctuations in that depression and anxiety increase while the person with PD is in the “off” state. What has been relatively unexplored is whether those persons with PD who have “on–off” phenomena differ psychologically in fundamental ways from those who do not have “on–off” phenomena. In the present study, depression and anxiety symptoms were assessed in 36 persons with PD (n = 14 with “on–off” phenomena, n = 22 without “on–off” phenomena). All those with “on–off” phenomena were assessed in their “on” state. Those persons with PD with “on–off” phenomena had significantly higher levels of anxiety than those without “on–off” phenomena. However, both groups, regardless of “on–off” status, were mildly depressed. Neurobiological interpretations of the results implicate the locus coeruleus in the pathogenesis of both “on–off” phenomena and anxiety, whereas psychological interpretations of the results involve the issues of learned helplessness and control over health symptoms in PD.