The Alternation of Gray Matter Morphological Topology in Drug-Naïve Tourette's Syndrome in Children

Reduced brain modularity may underlie accelerated disease progression in first-episode, drug-naïve depression

BACKGROUND

Depression presents considerable heterogeneity in its clinical course, yet reliable biomarkers for predicting individual trajectories remain elusive. Brain modularity, a fundamental topological property of structural networks, reflects the balance between functional segregation and integration. This study investigates the prognostic significance of brain modularity in depression progression and its association with white matter alterations.

METHODS

In this longitudinal study, 142 first-episode, medication-naïve patients with depression underwent diffusion MRI-based structural network analysis. Based on baseline modularity values, participants were stratified into high- and low-modularity groups. Key white matter network metrics-including rich-club connections, global efficiency, and nodal efficiency-were assessed. Depression severity was measured using the Hamilton Depression Rating Scale (HDRS). Logistic regression and receiver operating characteristic (ROC) analyses were employed to evaluate the prognostic utility of brain modularity in predicting symptom progression.

RESULTS

At baseline, patients with lower modularity exhibited disrupted network organization. Longitudinally, these individuals showed a steeper decline in rich-club connections, global efficiency, and left hippocampal nodal efficiency, alongside significantly greater HDRS worsening. Baseline modularity was inversely correlated with the rate of depression progression, with logistic regression confirming its predictive value. ROC analysis demonstrated robust classification performance.

CONCLUSIONS

Reduced brain modularity predisposes individuals to accelerated white matter network alterations and worsening depressive symptoms. These findings highlight brain modularity as a potential biomarker for identifying individuals at heightened risk of depression progression, offering a novel target for early intervention.

The Pathophysiology of Tics: An Anatomic Review

The underlying pathophysiology of tics in Tourette syndrome is a topic of major scientific interest. To date, there is an absence of consensus among researchers regarding the precise anatomic location responsible for tics. The goal of this article is to review the current understanding of these brain circuits and data supporting specific anatomic regions. In summary, current scientific evidence supports the likelihood of multiple areas of abnormality within cortico-basal ganglia-thalamocortical (CBGTC) circuitry or their connected brain regions. A reasonable anatomic hypothesis is that a disruption anywhere within specific circuitry can ultimately lead to the development of a tic disorder.

Therapeutic Approach to Primary Tic Disorders and Associated Psychiatric Comorbidities

BACKGROUND/OBJECTIVES

The treatment of tics and psychiatric comorbidities is crucial when they affect the patient's well-being and relationships. However, the optimal pharmacological treatment (PT) tailored to each patient's phenotype remains unclear. The primary objective of this study is to describe the clinical characteristics and treatment received for tics and psychiatric comorbidities in our cohort of children and adult patients with tic disorders. Additionally, a further aim was to quantify the severity of tics, comorbidities and overall severity, and the overall clinical changes observed during the follow-up.

METHODS

Retrospective descriptive study of patients with tic disorders under follow-up at our Tic Functional Unit from January 2022 to March 2024. Two independent neurologists retrospectively applied the Clinical Global Impression of Change (CGI-C) and the Clinical Global Impression of Severity (CGI-S) scales at baseline and at last assessment.

RESULTS

A total of 36 individuals were included (63.8% males, median age = 18 years, IQR 19): 94.4% with Tourette syndrome (TS), 2.8% with chronic tic disorder (CTD), and 2.8% with provisional tic disorder (PTD). A total of 86% had at least one psychiatric comorbidity, the most common being obsessive-compulsive symptomatology (OCS) (52%), anxiety (52%), and attention deficit hyperactivity disorder (ADHD) (35%). At last assessment, 26 patients (72.2%) were on undergoing PT for tics and 3 were receiving additional botulinum toxin. The most used medication for tics were aripiprazole (46.2%) and clonazepam (46.2%), and for psychiatric comorbidities, SSRIs (42.9%), methylphenidate (19%), and benzodiazepines (57.1%). Overall improvement according to the CGI-C scale was mild (CGI-C 3). Children and adolescents showed greater improvement than adults (CGI-C 2 vs. 3; p = 0.005). Aripiprazole and clonazepam produced similar outcomes in reducing CGI-C.

CONCLUSIONS

We observed a favorable clinical course in patients treated with aripiprazole and clonazepam, which appear to be better than that obtained with other treatments. We consider that clonazepam may be useful as a first-line monotherapy and as an adjuvant for both tics and comorbidities in selected cases.

Altered dynamic functional and effective connectivity in drug-naive children with Tourette syndrome

Tourette syndrome (TS) is a developmental neuropsychiatric disorder characterized by repetitive, stereotyped, involuntary tics, the neurological basis of which remains unclear. Although traditional resting-state MRI (rfMRI) studies have identified abnormal static functional connectivity (FC) in patients with TS, dynamic FC (dFC) remains relatively unexplored. The rfMRI data of 54 children with TS and 46 typically developing children (TDC) were analyzed using group independent component analysis to obtain independent components (ICs), and a sliding-window approach to generate dFC matrices. All dFC matrices were clustered into two reoccurring states, the state transition metrics were obtained. We conducted Granger causality and nodal topological analyses to further investigate the brain regions that may play the most important roles in driving whole-brain switching between different states. We found that children with TS spent more time in state 2 (PFDR < 0.001), a state characterized by strong connectivity between ICs, and switched more quickly between states (PFDR = 0.025) than TDC. The default mode network (DMN) may play an important role in abnormal state transitions because the FC that changed the most between the two states was between the DMN and other networks. Additionally, the DMN had increased degree centrality, efficiency and altered causal influence on other networks. Certain alterations related to executive function (r = -0.309, P < 0.05) and tic symptom ratings (r = 0.282; 0.413, P < 0.05) may represent important aspects of the pathophysiology of TS. These findings facilitate our understanding of the neural basis for the clinical presentation of TS.