Objective: The aim of this study was to identify the anatomical and functional changes related to anxiety, especially in the “fear circuit”, by comparing PD patients with and without anxiety.

Background: The point prevalence of anxiety in Parkinson’s disease (PD) is 31% [1]. Anxiety has a negative impact on both motor and non-motor symptoms as well as on quality of life [2]. Although the “fear circuit”, centred on the amygdala, seems to be involved, the underlying mechanisms remain largely unknown.

Method: Non-demented PD patients were enrolled. Anxiety was quantified using the Parkinson Anxiety Scale [3]. Structural MRI was used to compare cortical thickness and amygdala structure (volume, shape and texture) between the two groups. Resting-state functional MRI was used to compare functional connectivity changes in the amygdala and in resting-state functional networks.

Results: We included 118 patients: 34 with (A+) and 84 without (A-) anxiety. Anxious patients had a more advanced disease stage (Hoehn & Yahr staging) and significantly more sleep disorders, pain and fatigue. This group also had significantly lower scores for overall cognitive efficiency, attention and executive functions. Cortical atrophy clusters were identified in the A+ group in the bilateral prefrontal and parietal cortices and the left cingulate cortex. The texture and the shape of the left amygdala changed but the overall volume did not differ between groups. FC between the amygdala and the whole brain regions did not differ between groups. The internetwork resting-state FC was higher between the “fear circuit” and salience network and lower between left frontoparietal attentional and language networks in the A+ group.

Conclusion: Anxiety in PD is associated with structural and functional changes in the human brain fear circuit such as the amygdala and prefrontal, cingulate and parietal cortices. Theses changes could also explain the associated cognitive features. Further studies are needed to improve our understanding of the underlying mechanisms of anxiety related to PD.

References: 1. Broen MP, Narayen NE, Kuijf ML, et al. Prevalence of anxiety in Parkinson’s disease: A systematic review and meta‐analysis. Movement Disord 2016; 31: 1125–1133. 2. Leentjens AF, Dujardin K, Marsh L, et al. Symptomatology and markers of anxiety disorders in Parkinson’s disease: A cross-sectional study. Movement Disord 2011; 26: 484 492. 3. Leentjens AF, Dujardin K, Pontone GM, et al. The Parkinson Anxiety Scale (PAS): Development and validation of a new anxiety scale. Movement Disord 2014; 29: 1035 1043

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MDS Abstracts - https://www.mdsabstracts.org/abstract/anxiety-in-parkinsons-disease-is-associated-with-changes-in-the-brain-fear-circuit/