Abstract
BackgroundDepression in essential tremor (ET) has been constantly studied and reported, while the associated brain activity changes remain unclear. Recently, regional homogeneity (ReHo), a voxel-wise local functional connectivity (FC) analysis of resting-state functional magnetic resonance imaging, has provided a promising way to observe spontaneous brain activity.MethodsLocal FC analyses were performed in forty-one depressed ET patients, 49 non-depressed ET patients and 43 healthy controls (HCs), and then matrix FC and clinical depression severity correlation analyses were further performed to reveal spontaneous neural activity changes in depressed ET patients.ResultsCompared with the non-depressed ET patients, the depressed ET patients showed decreased ReHo in the bilateral cerebellum lobules IX, and increased ReHo in the bilateral anterior cingulate cortices and middle prefrontal cortices. Twenty-five significant changes of ReHo clusters were observed in the depressed ET patients compared with the HCs, and matrix FC analysis further revealed that inter-ROI FC differences were also observed in the frontal-cerebellar-anterior cingulate cortex pathway. Correlation analyses showed that clinical depression severity was positively correlated with the inter-ROI FC values between the anterior cingulate cortex and bilateral middle prefrontal cortices and was negatively correlated with the inter-ROI FC values of the anterior cingulate cortex and bilateral cerebellum lobules IX.ConclusionOur findings revealed local and inter-ROI FC differences in frontal-cerebellar-anterior cingulate cortex circuits in depressed ET patients, and among these regions, the cerebellum lobules IX, middle prefrontal cortices and anterior cingulate cortices could function as pathogenic structures underlying depression in ET patients.
Highlights
Depression in essential tremor (ET) has been constantly studied and reported, while the associated brain activity changes remain unclear
Demographic and clinical characteristics Demographic and clinical information is shown in Table 1, and the age, education level, tremor of onset, and scores on Tremor Rating Scale (TRS) parts A & B, TRS part C, the Essential Tremor Rating Assessment Scale (TETRAS), TETRAS-ADL, MMSE, HDRS-17 and HARS-14 in depressed ET patients showed a normal distribution (P = 0.63, 0.12, 0.32, 0.66, 0.33, 0.45, 0.27, 0.06, 0.97 and 0.06, respectively), and the tremor duration in the depressed ET patients showed a non-normal distribution (P = 0.035)
A significant correlation was observed between TRS parts A & B and TETR AS and between TRS part C and TETRAS-ADL (Pearson’s: r = 0.61 P = 3.542E-5; r = 0.47 P = 0.003), and a marginally significant correlation was observed between HDRS-17 scores and education level (Pearson’s r = 0.27 P = 0.09) in the depressed ET patients
Summary
Depression in essential tremor (ET) has been constantly studied and reported, while the associated brain activity changes remain unclear. Our previous studies examining the local [6], seed-based [7] and network [8] functional connectivity (FC) of RS-fMRI have demonstrated that cerebellar-thalamic-cortical pathway dysfunction is linked to tremor and cognitive impairment in ET patients. Among these FC analytical methods, local FC analysis has the benefits of evaluation of spontaneous neural synchronization activity, easy interpretation of the results, and high test-retest reliability; it does not require any a priori hypotheses and has gained increased attention. To our knowledge, no studies have employed local FC analysis to investigate the underlying spontaneous brain activity changes in depressed ET patients
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