Website Edition: August/September 2010

Editor's Choice Article and Review

Movement Disorders
Volume 25, Issue 7, 2010, Pages 838-845

Anxiety disorders in Parkinson's disease: Prevalence and risk factors
Nadeeka N.W. Dissanayaka, PhD 1 2 3 *, Anna Sellbach, FRACP 3, Sally Matheson, FRANZCP 3 4, John D. O'Sullivan, MD, FRACP 1 3, Peter A. Silburn, PhD, FRACP 1 2 3 5, Gerard J. Byrne, PhD, FRANZCP 3 4, Rodney Marsh, FRANZCP 1 3, George D. Mellick, PhD 1 2 6 *

1Neurology Research Centre, Royal Brisbane and Women's Hospital, Brisbane, Australia
2Eskitis Institute for Cell and Molecular Therapies, Griffith University, Brisbane, Australia
3School of Medicine, University of Queensland, Brisbane, Australia
4Department of Psychiatry, Royal Brisbane and Women's Hospital, Brisbane, Australia
5University of Queensland Centre For Clinical Research, Brisbane, Australia
6Department of Neurology, Princess Alexandra Hospital, Brisbane, Australia


Anxiety disorders are common in Parkinson's disease (PD) patients, yet are poorly studied. We examined the prevalence of anxiety disorders in PD, investigated the association between anxiety, and presentation and progression of PD, and studied for the first time the contribution of putative risk factors for anxiety in PD. A case-series of 79 PD patients recruited from neurology out-patient clinics was examined for anxiety disorders using the DSM-IV criteria. The Unified Parkinson's Disease Rating Scale and the Hoehn and Yahr Staging of PD were employed to understand the relationship between anxiety disorders, and the clinical presentation and severity of PD. A validated survey assessed putative risk factors for anxiety in PD. Twenty-five percent of PD patients were diagnosed with anxiety. Panic disorder, generalised anxiety disorder and social phobia were prevalent anxiety disorders. Comorbid depression with anxiety was observed (14%). The severity but not the duration of PD was positively related to anxiety. PD patients with postural instability and gait dysfunction symptom clustering were more likely to experience anxiety than tremor-dominant patients. While levodopa dosage had no relationship to anxiety, experience of dyskinesias or on/off fluctuations increased the risk. Lateralisation of PD had no association with anxiety. Anxiety disorders decreased with age and young onset PD patients were more likely to experience anxiety than the late onset subjects. Anxiety adds to the complexity of PD, lowering patients' quality of life. Future research can be directed to identify reactive and organic nature of anxiety in PD.

© 2010 The Movement Disorder Society

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Summary and Review by Laura Silveira-Moriyama, MD, PhD, Clinical Research Fellow, UCL Institute of Neurology, Queen Square, London

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The article chosen by the Website Editorial Board this month is "Anxiety Disorders in Parkinson's Disease: Prevalence and Risk Factors" by Nadeeka Dissanayaka and associates from Brisbane, Australia.

Dissanayaka and colleagues examined the point prevalence of anxiety disorders in a group of 79 non-demented PD subjects who fulfilled Queen Square Brain Bank criteria for the diagnosis of PD using a standardized interview called the MINI-plus, a scale that screens subjects for psychiatric disorders based on the DSM-IV criteria. The clinical data collected also included depressive symptoms, duration and severity of PD, levodopa equivalent dose and motor complications of PD. In addition, patients were also interviewed over the phone using a standardized interview created by the group to collect socio-demographic factors.

The mean age of the cohort was 67 years, the majority had mild to moderate PD and half presented with motor complications of anti-parkinsonian therapy. Using the MINI-plus, one quarter of the subjects had a diagnosis of current anxiety disorder (which is double of what is observed in elderly controls in Australia), and 14% had anxiety combined with depression. Social phobia was present in 13% of patients, and panic disorder in 7%, making those the most common diagnoses, in agreement with previous reports. The point prevalence of generalized anxiety disorder was 3%. This is lower than in some previous studies, and may be due to fact that Dissanayaka et al. have used strict criteria and excluded patients with major depressive symptoms. Using logistic regression models to estimate the odds ratio anxiety was associated with younger age of onset, worse motor severity (based on higher UPDRS and Hoehn and Yahr scores), presence of dyskinesias or motor fluctuations, and worse quality of life (based on higher score on the PDQ8). In contrast to depression where the prevalence does not seem to correlate with motor severity, this paper supports the current literature suggesting that patients with more disabling PD have a higher likelihood of developing anxiety symptoms.

Anxiety is a very common and yet poorly studied non-motor symptom of Parkinson's disease. Variations in methodology render estimates for the point prevalence of anxiety in PD from 3.6% to 40%. The diagnosis of anxiety is complicated by the fact that some of the symptoms used to diagnose anxiety are similar to those caused by PD, including tremor, autonomic changes and sleep difficulties. In the present study the presence of anxiety was associated with the severity of motor symptoms of PD. It is difficult to establish whether the very symptoms of PD could be the culprit for the worry and fear that patients often experience, and whether the anxiety itself may worsen the motor features, in particular freezing and tremor.

The main take-home message of this featured article is that anxiety disorders are not uncommon among PD patients, especially panic, social phobia and generalized anxiety disorder. Since anxiety is a manageable condition, every effort must be made in clinical practice to diagnose it accurately and in a timely manner. In the research setting, larger studies are needed to further characterize the phenotype of anxiety disorders in PD, and to explore its complicated relationship with depression and severity of motor features.

About Laura Silveira-Moriyama

Dr. Laura Silveira Moriyama graduated and trained in Neurology at the University of São Paulo, Brazil. She worked with Prof. Egberto Barbosa until 2004, when she moved to London to work in Queen Square under Prof. Andrew Lees' supervision, at the Reta Lila Weston Institute of Neurological Studies (RLWI). In 2009 she completed a PhD on the subject of olfaction in Parkinson’s disease and published a series of articles demonstrating that smell tests could be helpful in the differential diagnosis of parkinsonism and tremor, and that olfaction was impaired in various clinical manifestations of Lewy body disorders including pure autonomic failure and LRRK2 gene mutation carriers who present with parkinsonism. Currently she is a postgraduate fellow in Movement Disorders at the RLWI and continues to work with Prof. Andrew Lees teaming up with various international collaborators.