OBJECTIVE: This investigation sought to examine the potential moderating influence of heightened anxiety on working memory in Parkinson disease (PD) patients. Further, we wanted to determine whether this moderating influence of anxiety differentially affects PD patients with left hemibody (LBH) versus right hemibody (RHB) onset of motor symptoms. BACKGROUND: Research has examined the neurocognitive effects of depression in PD. However, a paucity of research has examined the effects of heightened anxiety in PD. We predicted that LHB PD patients with heightened anxiety would perform worse on a measure of working memory than RHB PD patients. METHOD: A total of 59 PD patients completed the state-trait anxiety inventory and were also administered the digit span subtest of the Wechsler Memory Scale-III. RESULTS: The results supported the hypotheses, indicating that the LHB PD patients with heightened anxiety performed significantly worse than the RHB PD patients with heightened anxiety and the LHB PD patients with low anxiety. CONCLUSIONS: These findings suggest that left hemibody onset PD patients may experience more disability in their activities of daily living. Future research should explore whether differences also exist between PD patients with and without the diagnosed anxiety disorders. Copyright © 2010 by Lippincott Williams & Wilkins.