Phenomenology of Atypical Anxiety Disorders in Parkinson's Disease: A Systematic Review

•What is the primary question addressed by this study?—A systematic review was conducted to better define and describe the clinical presentation of atypical anxiety in Parkinson's disease in order to help improve recognition, advance therapeutic development and ultimately optimize routine PD care.•What is the main finding of this study?—Across the 60 studies meeting inclusion criteria, estimates of atypical anxiety ranged from 15%–51%. We identified a diverse array of anxiety symptoms related to motor and non-motor symptoms of PD, to complications of PD medications (such as “on” and “off” fluctuations), and, to a lesser extent, to cognitive symptoms.•What is the meaning of the finding?—Atypical anxiety is highly prevalent, clinically relevant, heterogeneous in nature, and a key target for intervention in multidisciplinary PD care. Anxiety is a prominent concern in Parkinson's disease (PD) that negatively impacts quality of life, increases functional disability, and complicates clinical management. Atypical presentations of anxiety are under-recognized and inadequately treated in patients with PD, compromising global PD care. This systematic review focuses on the prevalence, symptomology and clinical correlates of atypical presentations of PD-related anxiety following PRISMA guidelines. Of the 60 studies meeting inclusion criteria, 14 focused on 'Anxiety Not Otherwise Specified (NOS)’ or equivalent, 31 reported on fluctuating anxiety symptoms, and 22 reported on 'Fear of Falling (FOF)'. Anxiety NOS accounted for a weighted mean prevalence of 14.9%, fluctuating anxiety for 34.19%, and FOF for 51.5%. These latter two exceeded the average reported overall prevalence rate of 31% for anxiety disorders in PD. We identified a diverse array of anxiety symptoms related to motor and non-motor symptoms of PD, to complications of PD medication (such as “on” and “off” fluctuations, or both), and, to a lesser extent, to cognitive symptoms. Atypical anxiety is common, clinically relevant, and heterogeneous in nature. A better understanding of the phenomenology, clinical course, and pathophysiology of varied forms of atypical anxiety in PD is needed to improve recognition, advance therapeutic development and ultimately optimize quality of life in PD.