Abstract
ObjectiveRecent studies have revealed a strong association between the cerebellum and psychiatric disorders. However, the structural changes in the cerebellar regions and functional connectivity (FC) patterns in patients with somatic symptom disorder (SSD) have not been elucidated.MethodsThirty-seven patients with SSD (29 drug-naive and 8 medicated patients) and 37 sex- and age-matched healthy controls (HCs) were recruited and underwent resting-state functional magnetic resonance imaging scans. The spatially unbiased infratentorial (SUIT) cerebellar atlas-based voxel-based morphometry was used to investigate the changes in cerebellar regional gray matter (GM). Seed-based FC was further computed to explore the pattern of abnormal FC across the whole brain. Correlations were calculated to investigate the relationship between cerebellar structural (and FC) changes and clinical characteristics.ResultsAfter controlling for age, sex, total intracranial volume, medication, and mean FD covariates, all patients with SSD had increased mean GM volume (GMV) in the posterior lobules of the cerebellum bilaterally when compared with HCs, specifically, in the bilateral cerebellar crura I and II. Patients with SSD showed significantly stronger FC between the right crura I and II and bilateral precuneus inferior parietal region, and postcentral gyrus, extending to the superior parietal lobe, cingulate gyrus, and the white matter subgyral. In addition to the two clusters, right lingual gyrus was also a surviving cluster with significantly higher FC. Partial correlation analysis revealed that the degree of regional GMV increases in the two significant clusters and the Hamilton Depression Scale (HAMD) score was negatively correlated. Moreover, the FC of right crura I and II with the left parietal lobe and right lingual gyrus were also negatively associated with the HAMD score.ConclusionsSSD exhibited significant microstructural changes and changes in FC pattern in the posterior cerebellar lobe. These results shed new light on the psychological and neural substrates of SSD and may serve as a potential treatment target for SSD based on the cerebellar area.
Highlights
Somatic symptom disorder (SSD) is a common neuropsychiatric condition that affects an estimated 5–7% of the general population (Kurlansik and Maffei, 2016)
In the current study, we investigated the differences in gray matter (GM) volume (GMV) of the cerebellum using voxelbased morphometry (VBM) of T1-weighted anatomical images, in combination with the cerebellum template from spatially unbiased infratentorial template (SUIT) (Diedrichsen, 2006) to test the following hypotheses: (1) SSD may exhibit altered GMV in the cerebellum; (2) SSD may display altered functional connectivity (FC) between cerebellar and whole brain; (3) these GM structural alterations may be associated with clinical measures and psychiatric symptoms, such as disease duration, accompanying anxiety, and depression symptom scores
There were no significant differences in age, sex, total intracranial volume (TIV), and mean frame-wise displacement (FD) between patients with SSD and healthy controls (HC)
Summary
Somatic symptom disorder (SSD) is a common neuropsychiatric condition that affects an estimated 5–7% of the general population (Kurlansik and Maffei, 2016). Patients with SSD have high rates of depression and anxiety, poor quality of life, frequent doctor visits, and high medical costs. It has become a major public health concern. Patients with SSD often present with excessive somatic complaints and develop excessive attention and sensitivity to physical discomfort, such as pain (Mobley et al, 2019). These findings raise the question of whether the emotional/cognitive regulatory function of the cerebellum may play a role in the pathophysiology of this disease
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