Reduced volume of the mediodorsal and anteroventral thalamus is associated with anxiety in Parkinson's disease: A cross-sectional 7-tesla MRI study

Background Parkinson's disease (PD)-related anxiety occurs frequently and may be associated with imbalance between anxiety-related circuits. While the thalamus is a shared region of these circuits, its role in PD-related anxiety has not been explored so far. Objective To identify changes in volume of the thalamus and its subnuclei in patients with PD-related anxiety. Methods Cognitively intact PD patients (n = 105) were divided into two groups based on their score on the Parkinson anxiety scale (PAS): 31 PD patients had anxiety (Anx-PD) and 74 did not have anxiety (non-Anx-PD). Forty-five healthy control subjects were included. Participants underwent 7-Tesla MRI scanning. Using automatic segmentation, the volumes of the thalamus and its subnuclei were measured, compared between the groups and regressed on the PAS. Results The volumes of the thalamus and its subnuclei did not significantly differ between the groups. However, in anxious PD patients, more severe anxiety was strongly associated with a smaller volume of the right medial thalamic subregion, specifically the right mediodorsal magnocellular nucleus and the right mediodorsal parvocellular nucleus (R = 0.63, ß PAS = −0.546, p-value model = 0.007 and R = 0.60, ß PAS = −0.547, p-value model = 0.016, respectively), and of the left anteroventral thalamus (R = 0.73, FDR p-value model = 0.002, ß PAS = −0.407, p-value PAS = 0.01). Conclusions A reduced volume of the mediodorsal and anteroventral thalamus, overlapping structures between the anxiety related circuits, are associated with more severe PD-related anxiety and may explain its high prevalence in the disease.