Does repeated ticking maintain tic behavior? An experimental study of eye blinking in healthy individuals

Optimizing behavior therapy for youth with Tourette's disorder

Tourette's Disorder (TD) is characterized by tics that cause distress and impairment. While treatment guidelines recommend behavior therapy as a first-line intervention, patients with TD may exhibit limited therapeutic response. Given the need to improve treatment outcomes, this study examined the efficacy of augmenting behavior therapy with D-cycloserine (DCS) to reduce tic severity in a placebo-controlled quick-win/fast-fail trial. Twenty youth with TD completed a baseline assessment to characterize tic severity, premonitory urges, medical history, and psychiatric comorbidity. Youth were randomly assigned to receive a single session of habit reversal training (HRT) augmented by either 50 mg of DCS or placebo. Two bothersome tics on the Hopkins Motor/Vocal Tic Scale (HM/VTS) were targeted for treatment during HRT. One week after the HRT session, youth completed a posttreatment assessment to evaluate change in the severity of bothersome tics. All assessments were completed by independent evaluators masked to treatment group. There was a Treatment Group by Time Interaction in favor of DCS-augmented HRT (p < 0.01), controlling for baseline tic severity, tic medication, and attention deficit hyperactivity disorder. Follow-up comparisons revealed small group differences at the treatment visit (d = 0.27), with the DCS group exhibiting slightly greater severity for targeted tics. There was a large group difference at posttreatment, in which the DCS group exhibited lower severity for targeted tics (d = 1.30, p < 0.001) relative to the placebo group. Findings demonstrate the preliminary enhancement of tic severity reductions by augmenting HRT with DCS compared with placebo augmentation.

Identifying the Symptom Severity in Obsessive-Compulsive Disorder for Classification and Prediction: An Artificial Neural Network Approach

The present study is aimed at identifying the most prominent determinants of OCD along with their strength to classify the OCD patients from healthy controls. The data for this cross-sectional study were collected from 200 diagnosed OCD patients and 400 healthy controls. The respondents were selected through purposive sampling and interviewed by using the Y-BOCS scale with the addition of a factor, worth of an individual in his family. The validity and reliability of data were assessed through Cronbach's alpha and confirmatory factor analysis. Artificial Neural Network (ANN) modeling was adopted to determine threatening determinants along with their strength to predict OCD in an individual. The results of ANN modeling depicted 98% accurate classification of OCD patients from healthy controls. The most contributing factors in determining the OCD patients according to normalized importance were the contamination and cleaning (100%); symmetric and perfection (72.5%); worth of an individual in the family (71.1%); aggressive, religious, and sexual obsession (50.5%); high-risk assessment (46.0%); and somatic obsessions and checking (24.0%).

Distinctive tics suppression network in Gilles de la Tourette syndrome distinguished from suppression of natural urges using multimodal imaging

Background and objectives

Gilles de la Tourette syndrome (GTS) is a neuropsychiatric disorder characterized by tics. A hallmark of GTS is the ability to voluntarily suppress tics. Our aim was to distinguish the neural circuits involved in the voluntary suppression of ocular tics in GTS patients from blink suppression in healthy subjects.

Methods

Fifteen GTS patients and 22 healthy control subjects were included in a multimodal study using eye-tracker recordings during functional MRI (fMRI). The ability to suppress tics/blinks was compared both on subjective (self-rating) and objective (eye-tracker) performance. For fMRI analysis we used a novel designed performance-adapted block design analysis of tic/blink suppression and release based on eye-tracker monitoring.

Results

We found that the subjective self-reported ability to suppress tics or blinks showed no significant correlation with objective task performance. In GTS during successful suppression of tics, the dorsal anterior cingulate cortex and associated limbic areas showed increased activation. During successful suppression of eye blinks in healthy subjects, the right ventrolateral prefrontal cortex and supplementary and cingulate motor areas showed increased activation.

Conclusions

These findings demonstrate that GTS patients use a characteristic limbic suppression strategy. In contrast, control subjects use the voluntary sensorimotor circuits and the classical ‘stop’ network to suppress natural urges. The employment of different neural suppression networks provides support for cognitive behavioral therapy in GTS.

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Neural networks of tic suppression are specific and differ from blink suppression.

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Tourette patients employ a limbic suppression strategy to suppress tics.

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Controls use sensorimotor circuits and ‘stop’ networks for blink suppression.

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Objective task performance is highly recommended during functional MRI of tics.

Neural correlates of prediction violations in boys with Tourette syndrome: Evidence from harmonic expectancy

OBJECTIVES

It has been suggested that Tourette syndrome (TS) might be associated with alterations of the attention system, but the nature of these alterations and the underlying neuroanatomical network remains elusive. We aimed at investigating the functional neuroanatomical modulators of attention allocation towards predictable versus unpredictable stimuli in boys with TS.

METHODS

Using functional magnetic resonance imaging, we ran a harmonic expectancy violation paradigm in 17 boys with TS and 23 matched healthy controls (HCs). We presented chord sequence in which the first four chords induced a strong expectancy for a harmonic chord at the next position. In 70% this expectancy was fulfilled (harmonic), in 30% the expectancy was violated (disharmonic).

RESULTS

HCs responded faster to the disharmonic compared to harmonic chords, indicating a stronger attention allocation towards unpredictable stimuli, while this effect was not found in boys with TS. HCs showed stronger anterior cingulate cortex (ACC) activation during disharmonic compared to harmonic chords. Boys with TS showed stronger ACC activation during harmonic chords, which was associated with greater tic severity.

CONCLUSIONS

Our findings indicate that boys with TS showed altered reactions towards predictable versus unpredictable stimuli in brain regions playing an important role in attention control. This might indicate altered allocation of attention towards those stimuli.

Tourette Syndrome research highlights 2014

About 200 journal articles reported research on Tourette syndrome and other tic disorders in 2014. Here we briefly summarize a few of the reports that seemed most important or interesting, ranging from animal models to human studies. Readers can comment on our choices or provide their own favorites using the tools on the online article.