Cerebellar morphology in Tourette syndrome and obsessive‐compulsive disorder

Abstract

Objective Neuroanatomical and functional imaging studies have identified the cerebellum as an integral component of motor and language control. Few studies, however, have investigated the role of the cerebellum in Tourette syndrome (TS), a condition defined by the presence of semi-involuntary movements and sounds. Methods Magnetic resonance imaging was conducted in 163 persons with TS and 147 control participants. Multivariate linear regression models were used to explore effects on cerebellar surface morphology and underlying volumes for the main diagnosis effects of TS as well as comorbid obsessive-compulsive disorder (OCD) and attention-deficit/hyperactivity disorder. Additionally, the correlations of symptom severity with cerebellar morphology were also assessed. Results The TS group demonstrated reduced volumes of the cerebellar hemispheres bilaterally that derived primarily from reduced gray matter in crus I and lobules VI, VIIB, and VIIIA. These decreased regional volumes accompanied increasing tic symptom severity and motoric disinhibition as demonstrated by a finger tapping test. Males had reduced volumes of these same regions compared with females, irrespective of diagnosis. Comorbid OCD was associated with relative enlargement of these regions in proportion to the increasing severity of OCD symptoms. Interpretation The cerebellum is involved in the pathogenesis of TS and tic-related OCD. Baseline gender differences in cerebellar morphology may in part account for the more prevalent expression of TS in males.

Functional neuroimaging in Tourette syndrome: recent perspectives

“…46 One study suggested that decreased regional volumes of cerebellar hemispheres were correlated with increased tic severity. 33 In an MRS study, it was shown that the GABA concentration in SM1 correlated negatively with motor tic severity. 53 Amphetamineinduced dopamin release in the ventral striatum was related to increased tic severity in one PET study, 61 while another PET study did not find any correlations between the TS-related metabolic covariance pattern (with increased activity bilaterally in premotor cortex and cerebellum, associated with relative reductions in striatum and orbitofrontal cortices) and severity of tics.…”

“…[30][31][32][33] Tobe et al 33 found decreased regional volumes of the cerebellar hemispheres during a finger-tapping test in patients with TS. The authors hypothesize that the cerebellum might be involved in the pathogenesis of TS.…”

Neurobiology of Tourette Syndrome: Current Status and Need for Further Investigation: Table 1.

“…Expanded perivascular spaces in the midbrain, usually considered a benign incidental finding on MRI, have also been correlated with stereotyped behaviors (Dávila et al, 2010). Disruption of corticocerebellar regulatory loops has been postulated based on MRI findings of reduced volumes of the cerebellum, primarily gray matter in crus I and lobules VI, VIIB, and VIIIA (Tobe et al, 2010). Last, altered MRI volumes of the hippocampus and amygdala and DTI diffusion indices (Neuner et al, 2011) has led to suggestions of direct limbic involvement in TS.…”

Multicenter Voxel-Based Morphometry Mega-Analysis of Structural Brain Scans in Obsessive-Compulsive Disorder

“…Assessing the effects of aging on brain structure in OCD is important, since age-by-disorder interactions may provide leads as to whether changes in brain structure are related to developing the disorder (present in young patients) or are the result of persistent OCD symptoms, compensatory processes, or treatment effects (present in older patients). Additionally, heterogeneity in clinical characteristics such as OCD illness severity (2), illness onset time or duration, medication exposure (12), comorbidity (13,14), and symptom dimensions (8, 9) may affect regional brain volume. In meta-analyses, only group-level demographic and clinical information is available, so accounting for effects of participant-level variability is problematic.…”