When Parkinson's disease interferes in a couple's life: A qualitative study.

Parkinson's disease (PD) is a neurodegenerative disease characterized by both motor and non-motor symptoms, including neuropsychiatric symptoms. Among these neuropsychiatric symptoms, anxiety is one of the most frequent with approximately 31% of PD patients experiencing significant anxiety symptoms. The underlying mechanisms of PD-related anxiety are still poorly understood. In PD, increased anxiety levels have been linked to structural and functional changes in anxiety-related circuits, consisting of the ‘fear circuit’ and the ‘limbic anxiety circuit’. The fear circuit is a neuronal circuit involved in fear processing and includes the amygdala, anterior cingulate cortex (ACC), the medial prefrontal cortex (mPFC), the insular cortex (IC), the hippocampus and the striatum. The limbic loop of the cortico-striato-thalamo-cortical circuit, also called the “limbic anxiety circuit”, is involved in emotional control. While altered functional connectivity has been observed between structures within these circuits, little is known about alterations of the cortical grey matter structures. In the general population, most studies on fear and anxiety disorders reported a decrease in cortical thickness of the ventromedial (vmPFC) and dorsolateral (dlPFC) prefrontal cortex, as well as cortical thinning in several other cortical regions, such as the lateral orbitofrontal cortex (OFC), medial OFC, ACC and caudal middle frontal gyrus. In PD patients, a reduced cortical thickness in the bilateral ACC and left parietal regions is reported in patients with anxiety compared to patients without anxiety. Additionally, higher levels of anxiety correlate with a reduction in grey matter volume in the ACC and precuneus. These findings suggest that cingulate and parietal areas may be involved in the underlying mechanisms of PD-related anxiety through disrupted emotion regulation, reflecting dysfunction in the fear circuit. However, studies focusing specifically on cortical thickness in patients with PD-related anxiety are limited, and so far, none was based on ultra-high field 7-Tesla MRI, which can reveal subtle cortical alterations that may be undetectable at 3 T resolution. Identifying changes in cortical thickness in these patients could help to decipher the underlying mechanisms of PD-related anxiety, which is essential for development of more effective treatment options. The aim of this study was to identify changes of brain cortical thickness in PD patients suffering from anxiety using ultra-high field 7-Tesla MRI scans. For PD patients with anxiety symptoms, we hypothesize a reduction of cortical thickness in areas involved in the anxiety circuits, such as the ACC and mPFC, as well as in the parietal regions, which were previously associated with anxiety.