Tic disorders in children and adolescents: does the clinical presentation differ in males and females? A report by the EMTICS group.

Tic disorders have a strong male predominance, with a male-to-female ratio of 4:1 in Tourette syndrome (TS) and 2:1 in persistent tic disorders. In other neurodevelopmental conditions, such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD), the disparity in sex distribution has been partially related to differences in symptom presentation between males and females. In tic disorders, however, little research has been conducted on this topic, probably due to the limited access to large samples with a significant proportion of females. The aim of this study was to describe sex differences in the clinical presentation of tic disorders in children and adolescents in one of the largest pediatric samples with TS/persistent tic disorders (n = 709, 23.3% females) recruited as part of the European Multicenter Tics in Children Study (EMTICS). Validated measures assessed the severity of tics and comorbid psychiatric symptoms. Using mixed-effect models, we found that sex had a significant influence on the severity of tics, ADHD symptoms, ASD symptoms, and emotional problems. Males had more severe symptoms than females, except for emotional problems. We also observed a statistically significant interaction between sex and age on the severity of tics and compulsions, with females showing higher symptom severity with increasing age than males. These findings indicate that the clinical presentation of TS/persistent tic disorders varies with sex. Males seem to exhibit a more noticeable pattern of clinical symptoms at a younger age that may contribute to their earlier detection in comparison to females.

Investigation of gene-environment interactions in relation to tic severity.

Tourette syndrome (TS) is a neuropsychiatric disorder with involvement of genetic and environmental factors. We investigated genetic loci previously implicated in Tourette syndrome and associated disorders in interaction with pre- and perinatal adversity in relation to tic severity using a case-only (N = 518) design. We assessed 98 single-nucleotide polymorphisms (SNPs) selected from (I) top SNPs from genome-wide association studies (GWASs) of TS; (II) top SNPs from GWASs of obsessive-compulsive disorder (OCD), attention-deficit/hyperactivity disorder (ADHD), and autism spectrum disorder (ASD); (III) SNPs previously implicated in candidate-gene studies of TS; (IV) SNPs previously implicated in OCD or ASD; and (V) tagging SNPs in neurotransmitter-related candidate genes. Linear regression models were used to examine the main effects of the SNPs on tic severity, and the interaction effect of these SNPs with a cumulative pre- and perinatal adversity score. Replication was sought for SNPs that met the threshold of significance (after correcting for multiple testing) in a replication sample (N = 678). One SNP (rs7123010), previously implicated in a TS meta-analysis, was significantly related to higher tic severity. We found a gene-environment interaction for rs6539267, another top TS GWAS SNP. These findings were not independently replicated. Our study highlights the future potential of TS GWAS top hits in gene-environment studies.

Activation in Children and Adolescents Treated With Selective Serotonin Reuptake Inhibitors: A Weighty Reason?

BACKGROUND: Activation is a behavioral adverse event related to the use of psychotropic medication. Its high incidence in pediatrics and in childhood-onset neuropsychiatric disorders suggests it may be linked to neurodevelopment. However, previous studies have scarcely examined the role that factors relevant to developmental pharmacokinetics, such as body weight, may play in the onset of activation in children and adolescents. METHODS: We conducted a retrospective analysis of hospitalized patients to identify the risk factors for activation in children and adolescents treated with selective serotonin reuptake inhibitors. Our focus was on factors related to development, including body weight, to explore the relationship between activation and neurodevelopmental processes. RESULTS: Among the 139 participants (mean age, 14 ± 2.3 years), activation appeared in 29 (20.9%). Age 12 years or younger and comorbid diagnosis of autism spectrum disorder were associated with statistically significant increases in the risk of activation, but no association was found regarding body weight. CONCLUSIONS: Our findings support the hypothesis that activation is closely linked to brain development processes. Longitudinal studies are needed to explore this line of research further.

Investigation of previously implicated genetic variants in chronic tic disorders: a transmission disequilibrium test approach.

Genetic studies in Tourette syndrome (TS) are characterized by scattered and poorly replicated findings. We aimed to replicate findings from candidate gene and genome-wide association studies (GWAS). Our cohort included 465 probands with chronic tic disorder (93% TS) and both parents from 412 families (some probands were siblings). We assessed 75 single nucleotide polymorphisms (SNPs) in 465 parent-child trios; 117 additional SNPs in 211 trios; and 4 additional SNPs in 254 trios. We performed SNP and gene-based transmission disequilibrium tests and compared nominally significant SNP results with those from a large independent case-control cohort. After quality control 71 SNPs were available in 371 trios; 112 SNPs in 179 trios; and 3 SNPs in 192 trios. 17 were candidate SNPs implicated in TS and 2 were implicated in obsessive-compulsive disorder (OCD) or autism spectrum disorder (ASD); 142 were tagging SNPs from eight monoamine neurotransmitter-related genes (including dopamine and serotonin); 10 were top SNPs from TS GWAS; and 13 top SNPs from attention-deficit/hyperactivity disorder, OCD, or ASD GWAS. None of the SNPs or genes reached significance after adjustment for multiple testing. We observed nominal significance for the candidate SNPs rs3744161 (TBCD) and rs4565946 (TPH2) and for five tagging SNPs; none of these showed significance in the independent cohort. Also, SLC1A1 in our gene-based analysis and two TS GWAS SNPs showed nominal significance, rs11603305 (intergenic) and rs621942 (PICALM). We found no convincing support for previously implicated genetic polymorphisms. Targeted re-sequencing should fully appreciate the relevance of candidate genes.

Children and adolescents with Tourette's disorder in the USA versus Argentina: behavioral differences may reflect cultural factors.

To explore behavioral differences as possible cultural factors in presentation of psychiatric comorbidity in two clinically referred, consecutively ascertained samples of youth with Tourette's disorder (TD) from New York and Buenos Aires. Subjects were evaluated between 2002 and 2010 at the Tics and Tourette's Clinical and Research Program at the New York University Child Study Center in New York and the Interdisciplinary Center for Tourette's, Obsessive Compulsive Disorder (OCD) and Associated Disorders (CITTTA)/Institute of Cognitive Psychology (INECO) in Buenos Aires. Demographic, diagnostic, tic severity (Yale Global Tic Severity Scale; YGTSS), clinical (Child Behavior Check List-Parent version; CBCL), and global functioning (Global Assessment of Functioning; GAF) data were compared using descriptive statistics. The sample included 111 subjects ages 6-17 years, who met DSM-IV-TR diagnostic criteria for TD. Findings revealed that the BA sample (n = 35) was significantly older at initial evaluation at the tic specialty clinic, and had higher frequency of oppositional defiant disorder (ODD), mood and non-OCD anxiety disorders than the NY sample (n = 76). There were no differences in gender distribution, age at tic onset or TD diagnosis, tic severity, proportion with current diagnoses of OCD/OC behavior or attention deficit hyperactivity disorder (ADHD), CBCL internalizing, externalizing, or total problems scores, YGTSS scores, or GAF scores. The observed similarities in demographic features, clinical presentation, rates of ADHD and OCD/OCB, and global impairment may reflect similar phenomenology and illness-related characteristics of TD in these referred youth. Differences in age at initial specialty clinic evaluation and rates of ODD, mood and non-OCD anxiety disorders may need further exploration before they may be considered to reflect cultural factors. Because of these limitations (e.g. small sample size), these results can be regarded only as preliminary.

Tourette syndrome in youth with and without obsessive compulsive disorder and attention deficit hyperactivity disorder.

Chronic tic disorders (TD) are consistently found to have high rates of comorbidity with obsessive-compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD). The purpose of this study is to compare the severity of TD only to TD with comorbid OCD or ADHD based on severity of tics, measures of psychopathology and additional comorbid diagnoses. Baseline data from 158 youth with a chronic TD who participated in two longitudinal studies were examined. Fifty-three percent (N = 85) of the youth also met criteria for a diagnosis of OCD, 38.6 % (n = 61) met criteria for ADHD and 24.1 % (N = 38) met criteria for both. Measures of interest addressed severity of tics, symptoms of anxiety, depression, ADHD, psychosocial stress, global functioning and the presence of comorbid diagnoses. Youth with comorbid TD and OCD were characterized by more severe tics, increased levels of depressive and anxious symptoms, heightened psychosocial stress and poorer global functioning. Youth with comorbid TD and ADHD did not differ from those with TD alone on measures of tic severity, but experienced greater psychosocial stress and poorer global functioning. Subjects with comorbid TD and OCD had more internalizing disorders than those without OCD, while those with comorbid ADHD were more likely to meet criteria for oppositional defiant disorder. TD with OCD is a more severe subtype of TD than TD without OCD. TD with ADHD is associated with higher psychosocial stress and more externalizing behaviors. Further research is needed into the underlying relationships between these closely associated conditions.

Pharmacologic Treatment of Comorbid Attention-Deficit/Hyperactivity Disorder and Tourette and Tic Disorders.

A complete and comprehensive medical and psychiatric evaluation is necessary to delineate tic symptoms from attention-deficit/hyperactivity disorder, and to prioritize the most problematic symptoms for intervention. Stimulants are the recommended first-line pharmacotherapy to treat attention-deficit/hyperactivity disorder symptoms in patients with tic disorders. Comprehensive behavioral intervention for tics is an effective behavioral therapy that is generally considered the first-line treatment of persistent tic disorders. α-Agonists can be added to stimulants if tics increase or be used as monotherapy to target attention-deficit/hyperactivity disorder and tics. Atomoxetine is also an excellent option to treat attention-deficit/hyperactivity disorder and tics.

Allopregnanolone: The missing link to explain the effects of stress on tic exacerbation?

The neurosteroid allopregnanolone (3α-hydroxy-5α-pregnan-20-one; AP) elicits pleiotropic effects in the central nervous system, ranging from neuroprotective and anti-inflammatory functions to the regulation of mood and emotional responses. Several lines of research show that the brain rapidly produces AP in response to acute stress to reduce the allostatic load and enhance coping. These effects not only are likely mediated by GABAA receptor activation but also result from the contributions of other mechanisms, such as the stimulation of membrane progesterone receptors. In keeping with this evidence, AP has been shown to exert rapid, potent antidepressant properties and has been recently approved for the therapy of moderate-to-severe postpartum depression. In addition to depression, emerging evidence points to the potential of AP as a therapy for other neuropsychiatric disorders, including anxiety, seizures, post-traumatic stress disorder and cognitive problems. Although this evidence has spurred interest in further therapeutic applications of AP, some investigations suggest that this neurosteroid may also be associated with adverse events in specific disorders. For example, our group has recently documented that AP increases tic-like manifestations in several animal models of tic disorders; furthermore, our results indicate that inhibiting AP synthesis and signalling reduces the exacerbation of tic severity associated with acute stress. Although the specific mechanisms of these effects remain partially elusive, our findings point to the possibility that the GABAergic activation by AP may also lead to disinhibitory effects, which could interfere with the ability of patients to suppress their tics. Future studies will be necessary to verify whether these mechanisms may apply to other externalising manifestations, such as impulse-control problems and manic symptoms.

Diagnosis and Management of Functional Tic-Like Phenomena.

Over the past 3 years, a global phenomenon has emerged characterized by the sudden onset and frequently rapid escalation of tics and tic-like movements and phonations. These symptoms have occurred not only in youth known to have tics or Tourette syndrome (TS), but also, and more notably, in youth with no prior history of tics. The Tourette Association of America (TAA) convened an international, multidisciplinary working group to better understand this apparent presentation of functional neurological disorder (FND) and its relationship to TS. Here, we review and summarize the literature relevant to distinguish the two, with recommendations to clinicians for diagnosis and management. Finally, we highlight areas for future emphasis and research.

Ticked Off: Anger Outbursts and Aggressive Symptoms in Tourette Disorder.

Tourette disorder is a complex neuropsychiatric syndrome of childhood onset characterized by multiple motor and phonic tics and is associated with high rates of psychiatric comorbidity. Symptoms of impulsive aggression (explosive outbursts or "rage") are commonly encountered in the clinical setting, cause significant morbidity, and pose diagnostic and treatment challenges. These symptoms may be multifactorial in etiology and result from a complex interplay of illness severity and psychosocial factors. Treatment strategies require careful differential diagnostic evaluation and include both behavioral and pharmacologic interventions.

Synaptic processes and immune-related pathways implicated in Tourette syndrome.

Tourette syndrome (TS) is a neuropsychiatric disorder of complex genetic architecture involving multiple interacting genes. Here, we sought to elucidate the pathways that underlie the neurobiology of the disorder through genome-wide analysis. We analyzed genome-wide genotypic data of 3581 individuals with TS and 7682 ancestry-matched controls and investigated associations of TS with sets of genes that are expressed in particular cell types and operate in specific neuronal and glial functions. We employed a self-contained, set-based association method (SBA) as well as a competitive gene set method (MAGMA) using individual-level genotype data to perform a comprehensive investigation of the biological background of TS. Our SBA analysis identified three significant gene sets after Bonferroni correction, implicating ligand-gated ion channel signaling, lymphocytic, and cell adhesion and transsynaptic signaling processes. MAGMA analysis further supported the involvement of the cell adhesion and trans-synaptic signaling gene set. The lymphocytic gene set was driven by variants in FLT3, raising an intriguing hypothesis for the involvement of a neuroinflammatory element in TS pathogenesis. The indications of involvement of ligand-gated ion channel signaling reinforce the role of GABA in TS, while the association of cell adhesion and trans-synaptic signaling gene set provides additional support for the role of adhesion molecules in neuropsychiatric disorders. This study reinforces previous findings but also provides new insights into the neurobiology of TS.

High-dose ondansetron reduces activation of interoceptive and sensorimotor brain regions.

Several psychiatric disorders involve abnormalities of interoception and associated neural circuitry centered on the insula. The development of interventions modulating interoceptive circuits could lead to novel treatment approaches for these disorders. The 5-HT3 receptor antagonist ondansetron is a good candidate for the modulation of interoceptive circuits, as 5-HT3 receptors are located abundantly on sensory pathways and ondansetron has shown some clinical utility in disorders characterized by sensory and interoceptive abnormalities. The present study tested the ability of three different doses of ondansetron to engage neural regions involved in interoception to determine the drug's utility as a therapeutic agent to target circuit abnormalities in patients. Fifty-three healthy subjects were randomized to receive a single 8-mg (n = 18), 16-mg (n = 17), or 24-mg (n = 18) dose of ondansetron and placebo before MRI scanning on separate days. Subjects performed an fMRI task previously shown to engage interoceptive circuitry in which they viewed videos depicting body movements/sensation and control videos. The results revealed a highly significant relationship between dosage and activation in bilateral insula, somatosensory and premotor regions, cingulate cortex, and temporal cortex for control but not body-focused videos. These effects were driven by a robust reduction in activation for ondansetron compared to placebo for the 24-mg group, with weaker effects for the 16-mg and 8-mg groups. In conclusion, high-dose ondansetron reduces activation of several areas important for interoception, including insula and sensorimotor cortical regions. This study reveals the potential utility of this drug in modulating hyperactivity in these regions in patients.

Interrogating the Genetic Determinants of Tourette's Syndrome and Other Tic Disorders Through Genome-Wide Association Studies.

OBJECTIVE: Tourette's syndrome is polygenic and highly heritable. Genome-wide association study (GWAS) approaches are useful for interrogating the genetic architecture and determinants of Tourette's syndrome and other tic disorders. The authors conducted a GWAS meta-analysis and probed aggregated Tourette's syndrome polygenic risk to test whether Tourette's and related tic disorders have an underlying shared genetic etiology and whether Tourette's polygenic risk scores correlate with worst-ever tic severity and may represent a potential predictor of disease severity. METHODS: GWAS meta-analysis, gene-based association, and genetic enrichment analyses were conducted in 4,819 Tourette's syndrome case subjects and 9,488 control subjects. Replication of top loci was conducted in an independent population-based sample (706 case subjects, 6,068 control subjects). Relationships between Tourette's polygenic risk scores (PRSs), other tic disorders, ascertainment, and tic severity were examined. RESULTS: GWAS and gene-based analyses identified one genome-wide significant locus within FLT3 on chromosome 13, rs2504235, although this association was not replicated in the population-based sample. Genetic variants spanning evolutionarily conserved regions significantly explained 92.4% of Tourette's syndrome heritability. Tourette's-associated genes were significantly preferentially expressed in dorsolateral prefrontal cortex. Tourette's PRS significantly predicted both Tourette's syndrome and tic spectrum disorders status in the population-based sample. Tourette's PRS also significantly correlated with worst-ever tic severity and was higher in case subjects with a family history of tics than in simplex case subjects. CONCLUSIONS: Modulation of gene expression through noncoding variants, particularly within cortico-striatal circuits, is implicated as a fundamental mechanism in Tourette's syndrome pathogenesis. At a genetic level, tic disorders represent a continuous spectrum of disease, supporting the unification of Tourette's syndrome and other tic disorders in future diagnostic schemata. Tourette's PRSs derived from sufficiently large samples may be useful in the future for predicting conversion of transient tics to chronic tic disorders, as well as tic persistence and lifetime tic severity.

Atomoxetine treatment of ADHD in children with comorbid Tourette syndrome.

OBJECTIVE: This study examines changes in severity of tics and ADHD during atomoxetine treatment in ADHD patients with Tourette syndrome (TS). METHOD: Subjects (7-17 years old) with ADHD (Diagnostic and Statistical Manual of Mental Disorders, DSM-IV) and TS were randomly assigned to double-blind treatment with placebo (n = 56) or atomoxetine (0.5-1.5 mg/kg/day, n = 61) for approximately 18 weeks. RESULTS: Atomoxetine subjects showed significantly greater improvement on ADHD symptom measures. Treatment was also associated with significantly greater reduction of tic severity on two of three measures. Significant increases were seen in mean pulse rate and rates of treatment-emergent nausea, decreased appetite, and decreased body weight. No other clinically relevant treatment differences were observed in any other vital sign, adverse event, laboratory parameter, or electrocardiographic measure. CONCLUSION: Atomoxetine is efficacious for treatment of ADHD and its use appears well tolerated in ADHD patients with comorbid TS.