Mechanisms

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Little is known about the etiology of anxiety disorders in PD, and they may be attributed to a combination of medical, neurochemical, and psychosocial phenomena. In a subset of patients, anxiety disorders are a "reactive" response secondary to the diagnosis of PD. However, when compared with non-PD patients with chronic illnesses and similar disability, patients with PD have significantly more severe anxiety (23). Epidemiologic observations indicate that patients with PD are at greater risk of developing anxiety disorders before the diagnosis of PD (24,25). These findings suggest that anxiety may be an early nonmotor phenotype of PD and that disability, although it may contribute to anxiety, is not the sole etiologic determinant.

Anxiety has been associated with motor fluctuations (20,26-28). During "off" phases, patients may experience feelings of despair, hopelessness, and panic that dissipate during the "on" phases (20). Frequency of freezing is also highly correlated with the presence of panic disorders and secondary panic attacks (29). However, emotional fluctuations do not always correlate temporally with motor state (30-31). In a study of 87 patients with PD, 29% had fluctuations in anxiety, 24% in motor, and 21% in mood (30). Of the patients with motor fluctuations, 75% had mood and/or anxiety fluctuations that did not necessarily correlate with motor state. Although the pattern of anxiety or mood fluctuations can be heterogeneous, adjustment of antiparkinson medications to minimize the motor fluctuations can be beneficial.

Neurochemically, degeneration of subcortical nuclei and ascending dopamine, norepinephrine, and serotonin (5-HT) pathways within the basal ganglia-frontal circuits may be responsible for symptoms of anxiety (32-35). Remy et al. (35) utilized [11C]RTI-32 positron emission tomography (PET), an in vivo marker of both dopamine and norepinephrine transporter binding, to localize differences between 8 depressed and 12 nondepressed patients with PD matched for age, disease duration, and antiparkinsonian medication. Exploratory analyses revealed that the severity of anxiety in the PD patients was inversely correlated with binding of [11C]RTI-32 in the amygdala, locus coeruleus, and thalamus. These results suggest that anxiety in PD might be associated with a specific loss of dopaminergic and noradrenergic innervation in the locus coeruleus and the limbic system.

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Getting to Know Anxiety

Getting to Know Anxiety

Stop Letting Anxiety Rule Your Life And Take Back The Control You Desire Right Now! You don't have to keep letting your anxiety disorder run your life. You can take back your inner power and change your life for the better starting today! In order to have control of a thing, you first must understand it. And that is what this handy little guide will help you do. Understand this illness for what it is. And, what it isn't.

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