Daniel M. Keller, PhD

July 06, 2016

BERLIN — Anxiety may affect up to 50% of all patients with Parkinson's disease (PD) at some point in their illness, but investigators have identified several predictors that may allow physicians to intervene and reduce the prevalence of this disabling condition.

Investigators, led by author Kangdi Zhu, MD, MSc, from the Department of Neurology at Leiden University Medical Center in the Netherlands, found that depression was the strongest predictor of anxiety in this patient population.

"Anxiety is a common feature in PD, that in all likelihood partly shares a common pathophysiological mechanism with depression," said Dr Zhu.

Dr Zhu reported the findings here at the 20th International Congress of Parkinson's Disease and Movement Disorders.

Dr Zhu noted that most studies of anxiety in PD have been cross-sectional, but this study was based on the Dutch PROfiling PARKinson's Disease (PROPARK) longitudinal cohort study of 414 patients with PD who were examined annually for 5 years. The study has documented a range of motor and nonmotor features.

The aim of the study was to "examine which factors are associated with longitudinal changes in anxiety levels" among patients with PD.

Of 409 patients with Hospital Anxiety and Depression Scale–Anxiety (HADS-A) subscale scores available at baseline, 67 (16%) had anxiety at baseline (score of 11 or greater on HADS-A). These patients were more often female, but age, disease duration, and age at PD onset were not associated with anxiety at baseline. The investigators noted that "patients with anxiety were more severely affected on several motor and nonmotor domains."

Of the 409, another 316 who did not have anxiety at baseline (HADS-A scores less than 11) were available for follow-up; 252 remained free from anxiety, and 64 developed anxiety during follow up.

In a linear mixed models analysis with depression as a covariate, depression was the factor most strongly associated with higher HADS-A scores. Without depression as a covariate, higher HADS-A scores over time were associated with female sex, greater cognitive impairment, more insomnia at baseline, and gastrointestinal and cardiovascular autonomic dysfunction.

For patients who did not have anxiety at baseline, a Cox proportional hazards model revealed that depressive symptoms, more cognitive impairment, insomnia, and gastrointestinal and cardiovascular autonomic dysfunction were independent predictors of the future development of anxiety.

The investigators proposed that insomnia and dysautonomia could contribute to anxiety in PD, and vice versa. Because of the association of cognitive dysfunction and the development of anxiety, they suggested monitoring patients with cognitive dysfunction more closely for symptoms of anxiety.

The authors noted that anxiety in PD may be episodic or nonepisodic and may vary with motor fluctuations. Motor deficits may induce anxiety, for example, because of a fear of falling from freezing.

Peter Schmidt, PhD, senior vice president and chief mission officer of the National Parkinson Foundation, Miami, Florida, told Medscape Medical News that anxiety is prevalent in PD, as shown in this study, and can be very disabling.

Dr Schmidt said one often hears about anxiety among patients with PD, "but it's not a paramount feature that people will talk about in terms of behavioral health in Parkinson's." More often people will talk about depression or later disease psychosis, "but anxiety is kind of left off the list as an important factor although it can be very disabling…. So it's good to have studies highlighting anxiety," he said.

There was no commercial support for the study. Dr Zhu and Dr Schmidt have disclosed no relevant financial relationships.

20th International Congress of Parkinson's Disease and Movement Disorders. Abstract 347. Presented June 20, 2016.

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