ensory hypersensitivity is a frequent feature in patients with TS and should not be associated uniquely or primarily with autism spectrum disorder. In 34 adults with TS, confirm what had previouslmy been decsribed mostly in youth with TS, and show that prominent in adults with tic disorder and is independently associated with obsessive-compulsive symptom severity." \citep{33173296}
Other
Emotional dysregulation is frequently observed in TS and thought to be related to the co-occurence of ADHD, eventually predisposing to explosive outbursts. However, it has has so far been mostly assessed in parent-reported questionnaires. Using an observational measure, Hagstrom observational measure, Hagstrom et al. directly examined children with TS only, ADHD only, TS+ADHD, and controls. Emotional dysregulation was clearly dependent on the presence of ADHD and could not be observed in TS only \citep{Hagstrøm2021}.
"Executive function in children with Tourette syndrome and attention-deficit/hyperactivity disorder: Cross-disorder or unique impairments?" \citep{31901563}
Symptoms suggesting disinhibition in TS \citep{Kurvits_2020}.
Review of self-injurious behavior in TS \citep*{32205150}.
Large study (N=720) comparing autistic and compulsive phenomena in children with a clinical diagnosis of either TS or ASD \citep{32443587}. (Need to read it.)
Aggressive symptoms in children with tics \citep{31396706}
Etiology
Genetics
Epigenetics
Environmental risk factors
Pathophysiology
Animal models
"The Sapap3-knockout mouse model manifests a spectrum of repetitive behaviours" \citep{Lamothe_2020}
Title: "Metastable attractors explain the variable timing of stable behavioral action sequences" abstract: "Here, we focus on the observation that the timing of self-initiated actions shows large variability even when they are executed in stable, well-learned sequences. Could this mix of reliability and stochasticity arise within the same circuit? We trained rats to perform a stereotyped sequence of self-initiated actions and recorded neural ensemble activity in secondary motor cortex (M2), which is known to reflect trial-by-trial action timing fluctuations. Using hidden Markov models we established a robust and accurate dictionary between ensemble activity patterns and actions. We then showed that metastable attractors, representing activity patterns with the requisite combination of reliable sequential structure and high transition timing variability, could be produced by reciprocally coupling a high dimensional recurrent network and a low dimensional feedforward one." \citep{Recanatesi_2020} (emphasis added)
Circuit in birdsong vocal and motor learning (doi: 10.1101/2020.03.14.991042)
Inhibiting parvalbumin-containing GABAergic neurons in a prefrontal-striatal circuit previously implicated in excessive habit generation (persistent rodent grooming to a tone before a drop of water on the face) impairs feedforward inhibition \citep{32029441} (reviewed in TAA conference talk 2021-05-14)
Pathological studies
Electrophysiology
Neuroimaging studies
"Alterations in cerebellar grey matter structure and covariance networks in young people with Tourette syndrome" \citep{Sigurdsson_2020}
Insula, urges \citep{Jackson_2020}
Seed-based fcMRI in TS \citep{32065948}
Structural and functional network studies of "rage attacks" in TS \citep{Atkinson_Clement_2020}
Interestingly and intriguingly, hippocampal volume measured at the onset of tics in 41 children with provisional tic disorder predicted tic severity at one-year follow-up, with with a larger hippocampus at baseline predicting worse tic severity at follow-up \citep{jcm9061715}.
Pharmacological studies
Very cool CSF study on endocannabinoids \citep{32272483}
Anti-D2R autoantibodies in TS? \citep*{32662071}
Clinical and neuropsychological studies
Impaired associative learning in TS \citep{32544176}
Other
A direct pathway from somatosensory cortex influencing movement
Treatment
Psychological interventions
"Tackle your tics" \citep{RN10144a}
Behavior therapy (BT) is considered to be the first line treatment since publication of the 2019 AAN guidelines, based on controlled randomized trials. In a naturalistic setting (children and adolescents with chronic tics, n=74) and over a 12 month follow-up period, it could be demonstrated that BT is and remains effective in 75% of patients analyzed, attesting not only to its efficacy but durability \citep{Andrén2021}.
Internet-based BT programs are investigated by multiple groups to make BT available to a larger number of patients, rendering it thus independent on the availability of trained practitioners and financial considerations in countries where psychotherapy is not reimbursed by social security. Rachamin et al. offer preliminary data on internet-based guided self-help comprehensive behavioral intervention for tics (ICBIT) in 25 youths (passive control group/waiting list, n=16), and show this approach to be both effective and well received over a 6 month period. Larger trials including an active control group are necessary to confirm these first positive impressions \citep{Rachamim2020}.
Medication
"Discontinuing ADHD medication may decrease quality of life for children" \citep*{laurel}\citep{32237294}
Neurosurgery
One site's long-term experience with DBS for OCD \citep{32184741}
Italian center's experience with antGPi vs. Cm-Pf DBS for TS \citep{32429219}
Structural connectivity predicts clinical DBS outcomes in TS \citep{32653920}