Anxiety in Parkinson’s Disease: a resting state functional connectivity study

Introduction. Anxiety is seen frequently in people with Parkinson’s disease (PD) (estimated 31% prevalence), but the underlying mechanism is not well understood. A recent review of neuroimaging studies of anxiety in PD, found patterns of altered functional connectivity (FC) within the fear and limbic cortico-striato-thalamocortical (CSTC) circuits, which are involved in processing fear and cognitively regulating anxiety. The review included 4 fMRI studies, which differed in their ROI inclusions. It has been suggested that the neurological changes associated with PD could affect the FC between and within these circuits. Therefore, we aimed to replicate these findings and hypothesized we would see a similar pattern of altered functional connectivity in specified regions of interest in PD patients with anxiety symptoms. Methods. The resting state fMRI scans of eighty-six PD patients were analyzed in CONN. The scans were first preprocessed using CONN’s default preprocessing pipeline,...Show moreIntroduction. Anxiety is seen frequently in people with Parkinson’s disease (PD) (estimated 31% prevalence), but the underlying mechanism is not well understood. A recent review of neuroimaging studies of anxiety in PD, found patterns of altered functional connectivity (FC) within the fear and limbic cortico-striato-thalamocortical (CSTC) circuits, which are involved in processing fear and cognitively regulating anxiety. The review included 4 fMRI studies, which differed in their ROI inclusions. It has been suggested that the neurological changes associated with PD could affect the FC between and within these circuits. Therefore, we aimed to replicate these findings and hypothesized we would see a similar pattern of altered functional connectivity in specified regions of interest in PD patients with anxiety symptoms. Methods. The resting state fMRI scans of eighty-six PD patients were analyzed in CONN. The scans were first preprocessed using CONN’s default preprocessing pipeline, and denoised. Functional connectivity between predefined ROIs, as indicated by Fisher’s Z-transformed correlations in BOLD signal between ROIs, was correlated with anxiety symptoms, as measured by the Anxiety subscale of the Hospital Anxiety and Depression Scale (HADS-A). We controlled for the effects of depressive, motor and cognitive symptoms. Results. Our results indicated no significant correlation (p>0.5 FDR corrected) between the connectivity among our specified ROIs and anxiety severity in this sample. Additionally, we observed very low Fisher’s Z transformed correlation values (β<0.1). Notably, our sample was characterized by mostly mild to moderate anxiety symptoms (mean = 5.31, standard deviation = 3.31, range: 0 – 17). Discussion. Our findings suggest that individuals with mild anxiety symptoms do not exhibit the same FC alterations in the fear and limbic CSTC networks as were described in previous research. It is possible this relationship is subtle in individuals with low anxiety levels, or that it is influenced by effects of dopaminergic medication or disease duration. Strengths and limitations of our study, and directions for future research are discussed.Show less

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Anxiety in Parkinson’s Disease: a resting state functional connectivity study