Research Sheds Light on the Source of Anxiety in Parkinson Disease

Despite that anxiety is a frequent nonmotor symptom associated with Parkinson disease (PD) that contributes negatively to quality of life, little is known about the pathophysiologic mechanism behind it, and a group of researchers set out to explore the connection.

In the study, which was recently published online in the Journal of Affective Disorders, researchers in Amsterdam, the Netherlands, used seed-based structural covariance—an analytic process based on the statistical correlation between the volume of different brain regions as measured with magnetic resonance imaging—to study the anatomical correlates of anxiety in persons with PD.

The 5 brain regions in which a tiny metal seed was placed in each patient were the basolateral amygdala, the centromedial superficial amygdala, the dorsal caudate nucleus, the dorsal-caudal putamen, and the accumbens nucleus (NAc). The researchers looked at the association between the presence of anxiety (as measured with the Beck Anxiety Inventory) and “seed-to-whole-brain structural covariance networks” in 115 patients with idiopathic PD.

The results showed that patients’ severity of anxiety correlated negatively with structural covariance between the left striatal subregions of the brain and the caudate nucleus on the opposite side of the brain. They also found that the severity of anxiety was associated with reduced structural covariance between the right dorsal caudate nucleus and the right ventrolateral prefrontal cortex, and between the left NAc and left dorsolateral prefrontal cortex. Structural covariance of the amygdala seeds showed no correlation with anxiety.

In short, the results showed that anxiety correlated with lower interstriatal and striatal-prefrontal connectivity, and cortico-striatal connections have a role in the pathophysiology of PD-related anxiety.

“We interpret these findings as a reduced interhemispheric cooperation between the left and right striatum and reduced prefrontal-striatal connectivity, possibly related to impaired ‘top-down’ regulation of emotions,” the researchers concluded, adding that the findings shed more light on the pathophysiology of anxiety in PD.

—Michael Gerchufsky

Reference:

Oosterwijk CS, Vriend C, Berendse HW, van der Werf YD, van den Heuvel OA. Anxiety in Parkinson’s disease is associated with reduced structural covariance of the striatum [published online July 20, 2018]. J Affect Disord. 2018;240:113-120. doi:10.1016/j.jad.2018.07.053.