Division of General Medicine and Geriatrics, Department of Medicine, Emory School of Medicine, 1648 Pierce Dr. NE, Atlanta, GA 30307, USA; Atlanta VA Center for Visual and Neurocognitive Rehabilitation, 1670 Clairmont Rd., Decatur, GA 30033, USA; Department of Rehabilitation Medicine, Emory School of Medicine, 1648 Pierce Dr. NE, Atlanta, GA 30307, USA. Electronic address: [Email]
Parkinson's disease (PD) is a neurodegenerative condition associated with aging characterized by loss of dopamine-producing neurons in the substantia nigra pars compacta and a reduction in dopamine levels in the striatum. PD is commonly treated using dopamine-replacement medication called levodopa. Levodopa has decreasing efficacy over time. Periods when levodopa is not effective at controlling symptoms of PD are called "OFF-time" or "medication-related motor fluctuations," (MRMF). One characteristic of PD is unilateral side of symptom onset. Previous studies have found that side of onset was associated with differential motor and cognitive PD-related symptoms. The main study objective was to examine differences in left and right onset PD patients and OFF-time as measured by the Movement Disorders Society Unified Parkinson Disease Rating Scale (MDS-UPDRS) Part IV Sum Score and Part IV item scores.