To determine whether side and type of initial motor symptoms in Parkinson disease (PD) predict risk for later development of cognitive impairment or depressive symptoms.
We recruited 124 non-demented patients with PD to participate in a cohort study of cognitive function and depressive symptoms that used validated neuropsychological tests and a depressive symptom inventory. We first reviewed the patients’ charts to determine their initial motor symptom and side of onset, and then classified the patients into 4 groups: right-sided onset tremor, right-sided onset bradykinesia/rigidity, left-sided onset tremor, and left-sided onset bradykinesia/rigidity. We excluded patients with bilateral symptom onset. We used analysis of variance on neuropsychological test performance and depressive symptoms to determine whether group classification affected risk of cognitive impairment or depressive symptoms. We controlled our analyses for disease duration and motor severity as measured by the Unified Parkinson Disease Rating Scale Part III motor score.
There were no differences in any cognitive measure by side and type of initial motor symptoms. The right-sided onset tremor group had the lowest depressive symptom scores, and no patient in any group reported severe depressive symptoms.
Our findings suggest that patterns of nigral cell loss correlating to the initial side and type of motor symptoms in PD are not related to the risk of later cognitive impairment. By contrast, patients with right-sided onset of tremor seem to have a lower risk of depressive symptoms than patients with other presentations.
Departments of *Neurology and Neurotherapeutics
‡Clinical Sciences, University of Texas Southwestern Medical Center, Dallas, TX
Supported in part by grants NIH 1RC1NS068983, NIH K23MH087739, and the Jean Walter Center for Research in Movement Disorders.
The authors declare no conflicts of interest.
Reprints: Richard B. Dewey, Jr, MD, Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, 5323 Harry Hines, Dallas, TX 75390-9036 (e-mail: firstname.lastname@example.org).
Received March 26, 2012
Accepted May 31, 2012