Prenatal and perinatal morbidity in children with Tourette syndrome and attention-deficit hyperactivity disorder

A Systematic Review and Meta-analysis of Prenatal, Birth, and Postnatal Factors Associated with Attention-Deficit/Hyperactivity Disorder in Children

Previous studies have shown mixed results on the relationship between prenatal, birth, and postnatal ("pregnancy-related") risk factors and attention-deficit/hyperactivity disorder (ADHD). We conducted meta-analyses to identify potentially modifiable pregnancy-related factors associated with ADHD. A comprehensive search of PubMed, Web of Science, and EMBASE in 2014, followed by an updated search in January 2021, identified 69 articles published in English on pregnancy-related risk factors and ADHD for inclusion. Risk factors were included in the meta-analysis if at least three effect sizes with clear pregnancy-related risk factor exposure were identified. Pooled effect sizes were calculated for ADHD overall, ADHD diagnosis, inattention, and hyperactivity/impulsivity. Odds ratios (OR) were calculated for dichotomous measures and correlation coefficients (CC) for continuous measures. Prenatal factors (pre-pregnancy weight, preeclampsia, pregnancy complications, elevated testosterone exposure), and postnatal factors (Apgar score, neonatal illness, no breastfeeding) were positively associated with ADHD overall; the findings for ADHD diagnosis were similar with the exception that there were too few effect sizes available to examine pre-pregnancy weight and lack of breastfeeding. Prenatal testosterone was significantly associated with inattention and hyperactivity/impulsivity. Effect sizes were generally small (range 1.1-1.6 ORs, -0.16-0.11 CCs). Risk factors occurring at the time of birth (perinatal asphyxia, labor complications, mode of delivery) were not significantly associated with ADHD. A better understanding of factors that are consistently associated with ADHD may inform future prevention strategies. The findings reported here suggest that prenatal and postnatal factors may serve as potential targets for preventing or mitigating the symptoms of ADHD.

Systematic Review and Meta-analysis of the Relationship Between Exposure to Parental Substance Use and Attention-Deficit/Hyperactivity Disorder in Children

Attention-deficit/hyperactivity disorder (ADHD) is characterized by persistent patterns of inattention, hyperactivity, and impulsiveness. Among US children and adolescents aged 3-17 years, 9.4% have a diagnosis of ADHD. Previous research suggests possible links between parental substance use and ADHD among children. We conducted a systematic review and meta-analysis of 86 longitudinal or retrospective studies of prenatal or postnatal alcohol, tobacco, or other parental substance use and substance use disorders and childhood ADHD and its related behavioral dimensions of inattention and hyperactivity-impulsivity. Meta-analyses were grouped by drug class and pre- and postnatal periods with combined sample sizes ranging from 789 to 135,732. Prenatal exposure to alcohol or tobacco and parent substance use disorders were consistently and significantly associated with ADHD among children. Other parental drug use exposures resulted in inconsistent or non-significant findings. Prevention and treatment of parental substance use may have potential for impacts on childhood ADHD.

Childhood Comorbidity Severity Impacts Adolescent Substance Consumption in Patients With Tourette Syndrome

BACKGROUND

This study explores the longitudinal impact of severity of Tourette Syndrome (TS), diagnosis and severity of Attention-Deficit/Hyperactivity Disorder (ADHD) and Obsessive-Compulsive Disorder (OCD), and guardian socioeconomic status on the level of substance use of pediatric patients with TS.

METHODS

A total of 314 pediatric patients with TS participated at time 1 (T1). During these visits, the severity of the patients' TS, ADHD, and OCD symptoms were assessed, along with their guardians' socioeconomic status. At time 2 (T2), between four and eight years later (median 5.6 years), 227 patients returned for a follow-up. Here, the patients answered questions about their intake of alcohol, cigarettes, and illegal substances. The relationship between the patients' diagnoses, symptom severity, and socioeconomic status at T1 and reported substance use at T2 was then analyzed using binary logistic regression.

RESULTS

Increased severity of ADHD and lower guardian socioeconomic status at T1 significantly increased the odds of later high cigarette consumption. Furthermore, both presence and increased severity of ADHD at T1 increased the odds of illegal substance consumption at T2. Conversely, increased severity of OCD at T1 significantly decreased cigarette and illegal substance consumption at T2, whereas both presence and increased severity of OCD decreased alcohol consumption.

CONCLUSIONS

Pediatric patients with TS with increased ADHD severity have increased risk of consuming illegal substances and high amounts of cigarettes as adolescents, whereas increased OCD severity may act as a protective factor. Having preventative conversations about substance consumption with patients with TS with high ADHD severity is important.

Association of Pre- and Perinatal Risk Factors With Tourette Syndrome or Chronic Tic Disorders in a Korean School-Age Population

Objectives

Tic disorders are highly heritable; however, growing evidence suggests that environmental factors play a significant role in their pathogenesis. Studies on these factors have been inconsistent, with conflicting results. Therefore, this study aimed to examine the associations of pre- and perinatal exposure to Tourette syndrome (TS) or chronic tic disorders (CTD) in Korean school-aged children.

Methods

This case-control study used data from a large prospective cohort study. The primary outcome was TS/CTD diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) criteria and Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version-Korean Version. Demographic, pre-, and perinatal information was obtained from the maternal questionnaires. Data between the TS/CTD and control groups were compared using the chi-squared or Student's t-test, as appropriate. Two-step logistic regression analyses were used to test the association between TS/CTD and pre- and perinatal risk factors.

Results

We included of 223 children (78 with TS/CTD and 145 controls). Significant differences in the demographic data between the two groups were observed. The male sex ratio, mean parental age, parental final education level, and family history of tics were included as confounders. In the final adjusted multivariable model, TS/CTD was significantly associated with antiemetic exposure during pregnancy (odds ratio [OR]=16.61, 95% confidence interval [CI] 1.49-185.22, p=0.02) and medically assisted reproduction (OR=7.89, 95% CI 2.28-27.28, p=0.01).

Conclusion

Antiemetic exposure and medically assisted reproduction are significantly associated with the risk of TS/CTD. These results should be replicated in future prospective and gene-by-environment studies.

Effect of maternal smoking during pregnancy on Tourette syndrome and chronic tic disorders among offspring: a systematic review and meta-analysis

Current studies have controversial reports about the effect of maternal smoking during pregnancy (MSDP) on the risk of psychiatric disorders among offspring. The purpose of this systematic review and meta-analysis was to assess the effect of MSDP on the risk of Tourette syndrome (TS) and chronic tic disorders (CTD) among offspring. A systematic search using PubMed, Scopus, and Web of Science was conducted up to July 2019 to retrieve potential studies in English. Fixed and random-effects meta-analyses was performed to estimate pooled relative risk (RR) with 95% confidence interval (CI) according to heterogeneity. The methodological quality of the included studies was evaluated using the Newcastle-Ottawa Scale. Heterogeneity among studies was explored using the I² statistic. Of the 641 studies from the initial search, 7 were included in the quantitative synthesis (3 cohort and 4 case control studies). Overall, MSDP increased the risk of TS and CTD among the offspring by 35% (pooled RR, 1.35; 95% CI, 1.17–1.56; I²=45.8%; P-value=0.08). The results of this meta-analysis revealed that there is a significant association between MSDP and the risk of TS and CTD in offspring, and MSDP may be considered a potential risk factor for TS and CTD.

Disentangling Tourette syndrome heterogeneity through hierarchical ascendant clustering

AIM

To explore the heterogeneity of Tourette syndrome as part of a neurodevelopmental spectrum.

METHOD

Using hierarchical ascendant clustering based on tic symptoms, developmental milestones, and neurodevelopmental comorbidities, we analyzed the heterogeneity of Tourette syndrome phenotypes in a sample of 174 children and adolescents with Tourette syndrome referred to a tertiary university clinic.

RESULTS

The model yielded three distinct clusters characterized as follows. In cluster 1, we found many neurodevelopmental comorbidities (including intellectual disabilities, autism spectrum disorder, attention-deficit-hyperactivity disorder [ADHD], and learning disabilities) and academic impairments. In cluster 2, patients had no other neurodevelopmental comorbidities. In cluster 3, patients had higher intelligence, a high frequency of attentional impairment, school problems related to both ADHD and unspecific attention difficulties, and handwriting problems related to the tics themselves. Interestingly, clusters did not differ in terms of family history or anxious-depressive comorbidities. The only other differences that emerged were related to prenatal or perinatal risk factors (more represented in cluster 1) and treatment profiles (higher rates of stimulants in cluster 1).

INTERPRETATION

We conclude that from a phenotypical perspective, Tourette syndrome is a heterogeneous syndrome with at least three main clusters that may help in addressing the etiological basis of Tourette syndrome and specific rehabilitative and therapeutic approaches.

WHAT THIS PAPER ADDS

The clustering of Tourette syndrome based on comorbidity with other neurodevelopmental conditions reveals three clusters. A group of patients with Tourette syndrome show school difficulties related to non-specific attention and writing problems. Analysing only children and adolescents helps to distinguish between developmental comorbid conditions and coexistent disorders.

Perinatal risk factors in Tourette's and chronic tic disorders: a total population sibling comparison study

Adverse perinatal events may increase the risk of Tourette's and chronic tic disorders (TD/CTD), but previous studies have been unable to control for unmeasured environmental and genetic confounding. We aimed to prospectively investigate potential perinatal risk factors for TD/CTD, taking unmeasured factors shared between full siblings into account. A population-based birth cohort, consisting of all singletons born in Sweden in 1973-2003, was followed until December 2013. A total of 3 026 861 individuals were identified, 5597 of which had a registered TD/CTD diagnosis. We then studied differentially exposed full siblings from 947 942 families; of these, 3563 families included siblings that were discordant for TD/CTD. Perinatal data were collected from the Medical Birth Register and TD/CTD diagnoses were collected from the National Patient Register, using a previously validated algorithm. In the fully adjusted models, impaired fetal growth, preterm birth, breech presentation and cesarean section were associated with a higher risk of TD/CTD, largely independent from shared family confounders and measured covariates. Maternal smoking during pregnancy was associated with risk of TD/CTD in a dose-response manner but the association was no longer statistically significant in the sibling comparison models or after the exclusion of comorbid attention-deficit/hyperactivity disorder. A dose-response relationship between the number of adverse perinatal events and increased risk for TD/CTD was also observed, with hazard ratios ranging from 1.41 (95% confidence interval (CI): 1.33-1.50) for one event to 2.42 (95% CI: 1.65-3.53) for five or more events. These results pave the way for future gene by environment interaction and epigenetic studies in TD/CTD.

Research Review: The role of obstetric and neonatal complications in childhood attention deficit and hyperactivity disorder - a systematic review

BACKGROUND

Attention deficit and hyperactivity disorder (ADHD) is a developmental disorder characterized by an inability to sustain attention, activity levels and impulse control, and, according to the latest studies, the prevalence is about 8% and in some countries less than 1%. Currently, it is well-known that complications during the perinatal period have significant implications on child's physical and mental health. Purpose of the present paper is to review the literature about the association between perinatal complications and future risk of an ADHD diagnosis.

METHODS

A research in the main database sources has been conducted to obtain a systematic review on the perinatal risk factors of ADHD.

RESULTS

Among perinatal complications, available data indicate low birth weight (LBW) (Cohen's d effect size range: 0.31-1.64-small effect size) and preterm birth (PB) (range d: 0.41-0.68) as the most important factors associated with a future diagnosis of ADHD.

CONCLUSIONS

PB and LBW children should be carefully monitored for an early diagnosis of ADHD limiting the impact of the disease in life span. A systematic review focusing on these risk factors have not been published until now, in the next future preventive strategies should be developed in order to minimize ADHD onset.

Additive effect of congenital heart disease and early developmental disorders on attention-deficit/hyperactivity disorder and autism spectrum disorder: a nationwide population-based longitudinal study

In this retrospective nationwide population-based case-control study, we investigated the impact of congenital heart disease (CHD) on the development of attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), which remains unclear. Children aged <18 years that were diagnosed with CHD (n = 3552) between January 1, 1997 and December 31, 2009 were identified from the National Health Insurance Research Database in Taiwan. Non-CHD controls (n = 14,208) matched for age and sex (1:4) were selected from the same dataset. All subjects were observed until December 31, 2011 or their death. Comorbid perinatal conditions and early developmental disorders (EDD) that were diagnosed before ADHD and ASD diagnosis were also analyzed. The incidence rates of perinatal comorbidities, EDD, ADHD, and ASD were higher in the CHD group than in the control group. Multivariate Cox regression analysis revealed that the CHD group had an increased risk of developing ADHD (adjusted hazard ratio [aHR] 2.52, 95% confidence interval CI 1.96-3.25) and ASD (aHR 1.97, 95% CI 1.11-3.52) after adjusting for confounding comorbidities. EDD, but not perinatal comorbidities were also independent risk factors for ADHD and ASD after adjustment. Subgroup analysis indicated that the risk for ADHD (HR 16.59, 95% CI 12.17-22.60) and ASD (HR 80.68, 95% CI 39.96-176.12) was greatly increased in CHD subjects with EDD than in non-CHD subjects without EDD. These findings suggested that CHD at birth and EDD during early childhood were two independent risk factors for ADHD and ASD and that concurrent CHD and EDD might additively increase these risks.

Postnatal testosterone may be an important mediator of the association between prematurity and male neurodevelopmental disorders: a hypothesis

Children born premature are at risk for neurodevelopmental disorders, including autism and schizophrenia. This piece advances the hypothesis that altered androgen exposure observed in premature infants is an important mediator of the neurodevelopmental risk in males associated with prematurity. Specifically, the alterations of normative physiologic postnatal activations of the hypothalamic-pituitary-gonadal axis that occur in preterm males are hypothesized to contribute to the risk of neuropsychiatric pathology of prematurity through altered androgen-mediated organizational effects on the developing brain. The physiology of testosterone and male central nervous system development in full-term births is reviewed and compared to the developmental processes of prematurity. The effects of the altered testosterone physiology observed within prematurity outside of the central nervous system are reviewed as a segue into a discussion of the effects within the nervous system, with a special focus on autism spectrum disorders and attention deficit hyperactivity disorder. The explanatory power of this model is reviewed as a supplement to the preexisting models of prematurity and neurodevelopmental risk, including infection and other perinatal central nervous system insults. The emphasis is placed on altered androgen exposure as serving as just one among many mediators of neurodevelopmental risk that may be of interest for further research and evidence-based investigation. Implications for diagnosis, management and preventative treatments conclude the piece.

Further evidence for the role of pregnancy-induced hypertension and other early life influences in the development of ADHD: results from the IDEFICS study

The aim of this study is to investigate whether in addition to established early risk factors other, less studied pre-, peri-, and postnatal influences, like gestational hypertension or neonatal respiratory disorders and infections, may increase a child's risk of developing attention-deficit/hyperactivity disorders (ADHD). In the IDEFICS study more than 18,000 children, aged 2-11.9 years, underwent extensive medical examinations supplemented by parental questionnaires on pregnancy and early childhood. The present analyses are restricted to children whose parents also completed a supplementary medical questionnaire (n = 15,577), including the question whether or not the child was ever diagnosed with ADHD. Multilevel multivariable logistic regression was used to assess the association between early life influences and the risk of ADHD. Our study confirms the well-known association between maternal smoking during pregnancy and a child's risk of ADHD. In addition, our study showed that children born to mothers younger than 20 years old were 3-4 times more likely to develop ADHD as compared to children born to mothers aged 25 years and older. Moreover, we found that children whose mothers suffered from pregnancy-induced hypertension had an approximately twofold risk of ADHD (OR 1.95; 95% CI 1.09-3.48). This also holds true for infections during the first 4 weeks after birth (OR 2.06; 95% CI 1.05-4.04). In addition, although not statistically significant, we observed a noticeable elevated risk estimate for neonatal respiratory disorders (OR 1.76; 95% CI 0.91-3.41). Hence, we recommend that these less often studied pre-, peri, and postnatal influences should get more attention when considering early indicators or predictors for ADHD in children. However, special study designs such as genetically sensitive designs may be needed to derive causal conclusions.

Pre- and perinatal complications in relation to Tourette syndrome and co-occurring obsessive-compulsive disorder and attention-deficit/hyperactivity disorder

Pre- and perinatal complications have been implicated in the onset and clinical expression of Tourette syndrome albeit with considerable inconsistencies across studies. Also, little is known about their role in co-occurring obsessive-compulsive disorder (OCD) and attention-deficit/hyperactivity disorder (ADHD) in individuals with a tic disorder. Therefore, we aimed to investigate the role of pre- and perinatal complications in relation to the presence and symptom severity of chronic tic disorder and co-occurring OCD and ADHD using data of 1113 participants from the Tourette International Collaborative Genetics study. This study included 586 participants with a chronic tic disorder and 527 unaffected family controls. We controlled for age and sex differences by creating propensity score matched subsamples for both case-control and within-case analyses. We found that premature birth (OR = 1.72) and morning sickness requiring medical attention (OR = 2.57) were associated with the presence of a chronic tic disorder. Also, the total number of pre- and perinatal complications was higher in those with a tic disorder (OR = 1.07). Furthermore, neonatal complications were related to the presence (OR = 1.46) and severity (b = 2.27) of co-occurring OCD and also to ADHD severity (b = 1.09). Delivery complications were only related to co-occurring OCD (OR = 1.49). We conclude that early exposure to adverse situations during pregnancy is related to the presence of chronic tic disorders. Exposure at a later stage, at birth or during the first weeks of life, appears to be associated with co-occurring OCD and ADHD.

Prenatal Maternal Smoking and Increased Risk for Tourette Syndrome and Chronic Tic Disorders

OBJECTIVE

We assessed the role of prenatal maternal smoking in risk for Tourette syndrome and chronic tic disorder (TS/CT) and pediatric-onset obsessive-compulsive disorder (OCD).

METHOD

In an analysis of 73,073 singleton pregnancies from the Danish National Birth Cohort, we calculated incidence rates (IR) per 1,000 person-year for TS/CT and OCD. We then determined crude and adjusted hazard ratios and 95% CIs associated with prenatal maternal smoking, considering smoking as a dichotomous (yes/no) variable or a stratified variable (no smoking, light smoking, and heavy smoking [≥10 cigarettes/day]). Additional analyses examined the effect of maternal smoking on risk for TS/CT with other comorbid psychiatric conditions.

RESULTS

In final adjusted analyses, heavy smoking was associated with a 66% increased risk for TS/CT (adjusted hazard ratio = 1.66, 95% CI = 1.17-2.35). In addition, heavy smoking was associated with a 2-fold increased risk for TS/CT with comorbid attention-deficit/hyperactivity disorder (ADHD), and both light and heavy smoking were associated with a more than 2-fold increased risk for TS/CT with any non-ADHD psychiatric comorbidity. Our parallel analyses of pediatric-onset OCD were likely underpowered but showed similar relationships.

CONCLUSION

Prenatal maternal smoking was associated with increased risk for TS/CT as well as TS/CT with comorbid psychiatric conditions, even after adjustment for several important variables, including maternal psychiatric history, socioeconomic status, and partner smoking. Our findings point to a pathway linking prenatal tobacco exposure and altered brain development to TS/CT.

The First World Congress on Tourette Syndrome and Tic Disorders: Controversies and Hot Topics in Etiology and Treatment

The first World Congress on Tourette Syndrome and Tic Disorders was held in London, June 2016 by the Tourette Association of America, Tourettes Action (UK), and the European Society for the Study of Tourette Syndrome. Presentations arising from large-scale collaborative projects were an important component of the scientific programme. This article focuses on areas raised in the hot topics session and two moderated debates, which covered emerging research in etiology and treatment. The hot topics ranged across genetics, arguably including the first confirmed Tourette Syndrome (TS) susceptibility gene NRXN1, neurocognition, and neurophysiology, including the possibility of a neurocognitive endophenotype for TS and the use of depth and cortical surface electrodes to investigate the neurophysiology of tics on the background of the evolving field of deep brain stimulation (DBS), to novel treatment approaches such as dental orthotics and an online behavioral intervention. The debates aired controversies in treatment; pharmacotherapy vs. behavioral treatment and the place of medical cannabinoids. These sessions demonstrate the vibrancy of a field that has considerably expanded in the last decade, the significant progress that has been made, and the direction that some of the most fruitful next phases of research will take.

Tourette syndrome in children and adolescents: aetiology, presentation and treatment

Tourette syndrome is a complex neuropsychiatric disorder of juvenile onset, characterised by motor and phonic tics. It is associated with a number of comorbid psychiatric conditions and a reduced quality of life in the young person and with parenting stress, caregiver burden and psychopathology in the parents. The global prevalence (about 1%) is higher than previously thought, with a strong male preponderance. Evidence is emerging that Tourette syndrome is not a unified disorder; rather, it encompasses a number of subtypes, characterised by complexity of tics and the simultaneous presence of other behaviours or disorders. This article discusses the aetiology of the syndrome, and examines its clinical features and comorbid psychiatric conditions and psychopathologies. Assessment and diagnosis are also discussed. Psychoeducation is a cornerstone of management, augmented with behavioural and/or pharmacological treatments. Newer therapies, such as deep brain stimulation, offer tantalising possibilities, but further research is still needed.

Provisional Tic Disorder: What to tell parents when their child first starts ticcing

The child with recent onset of tics is a common patient in a pediatrics or child neurology practice. If the child’s first tic was less than a year in the past, the diagnosis is usually Provisional Tic Disorder (PTD). Published reviews by experts reveal substantial consensus on prognosis in this situation: the tics will almost always disappear in a few months, having remained mild while they lasted. Surprisingly, however, the sparse existing data may not support these opinions.

PTD may have just as much importance for science as for clinical care. It provides an opportunity to prospectively observe the spontaneous remission of tics. Such prospective studies may aid identification of genes or biomarkers specifically associated with remission rather than onset of tics. A better understanding of tic remission may also suggest novel treatment strategies for Tourette syndrome, or may lead to secondary prevention of tic disorders.

This review summarizes the limited existing data on the epidemiology, phenomenology, and outcome of PTD, highlights areas in which prospective study is sorely needed, and proposes that tic disorders may completely remit much less often than is generally believed.

Prenatal Maternal Smoking and Tourette Syndrome: A Nationwide Register Study

This is the first nationwide register-based study to examine the relationship between prenatal maternal smoking and Tourette syndrome. A total of 767 children diagnosed with Tourette syndrome were identified from the Finnish Hospital Discharge Register. Each case was matched to four controls. Information on maternal smoking during pregnancy was obtained from the Finnish Medical Birth Register. Conditional logistic regression models were used for statistical analyses. Prenatal maternal smoking was associated with Tourette syndrome when comorbid with ADHD (OR 4.0, 95 % CI 1.2-13.5, p = 0.027 for exposure during first trimester, OR 1.7, 95 % CI, 1.05-2.7, p = 0.031 for exposure for the whole pregnancy). There was no association between maternal smoking during pregnancy and Tourette syndrome without comorbid ADHD (OR 0.5, 95 % CI 0.2-1.3, p = 0.166, OR 0.9, 95 % CI 0.7-1.3, p = 0.567). Further research is needed to elucidate the mechanisms behind the association between prenatal maternal smoking and Tourette syndrome with comorbid ADHD.

Tourette syndrome and comorbid ADHD: causes and consequences

Attention deficit hyperactivity disorder (ADHD) is the most common comorbid condition in patients with Tourette syndrome (TS). The co-occurrence of ADHD and TS is in most cases associated with a higher social and psychopathological impairment. Comorbidity between Tourette and ADHD appears to have a complex and partially known pathogenesis in which genetic, environmental, and neurobiological factors can be implicated. Genetic studies have revealed an involvement of dopaminergic, catecholaminergic, and GABAergic genes that modulated the activity of neurotransmitters. Furthermore, there are a lot of networks implicated in the development of ADHD and TS, involving cortical and striatal areas and basal ganglia. Although a large number of studies tried to find a common pathogenesis, the complex pathways responsible are not clear. The genes implicated in both disorders are currently unidentified, but it is probable that epigenetic factors associated with neural modifications can represent a substrate for the development of the diseases.

CONCLUSION

In this paper, recent advances in neurobiology of ADHD and TS are reviewed, providing a basis for understanding the complex common pathogenesis underlying the frequent co-occurrence of the two conditions and the therapeutic choices.

Prenatal risk factors for Tourette Syndrome: a systematic review

BACKGROUND

Tourette Syndrome (TS) appears to be an inherited disorder, although genetic abnormalities have been identified in less than 1% of patients, and the mode of inheritance is uncertain. Many studies have investigated environmental factors that might contribute to the onset and severity of tics and associated comorbidities such as obsessive compulsive disorder (OCD) and attention deficit hyperactive disorder (ADHD). A systematic review and qualitative analysis were performed to provide a broad view of the association between pre- and perinatal factors and TS.

METHODS

The Medline, Embase and PsycINFO databases were searched using terms specific to Tourette's syndrome and keywords such as "pregnancy", "prenatal", "perinatal", "birth" and "neonatal". Studies were limited to studies on human subjects published in English or French through October 2012.

RESULTS

22 studies were included. Studies were of limited methodological quality, with most samples derived from specialty clinics, and most exposures ascertained retrospectively. The majority of the results for demographic factors of parents, including age, education, socioeconomic status, and marital status, revealed no significant association with the onset of TS, or the presence of comorbidity. Many factors were reported to be significantly associated with the onset of TS, the presence of comorbidity and symptom severity, but the most consistently reported factors were maternal smoking and low birth weight.

CONCLUSIONS

There are few studies evaluating the relationship between pre and perinatal events and TS, and existing studies have major limitations, including the use of clinic rather than epidemiologically derived samples, retrospective data collection on pre and perinatal events and multiple hypothesis testing without appropriate statistical correction. The mechanism by which prenatal and perinatal adversities could lead to TS onset or symptom severity is unknown, but may be related to changes in the dopaminergic system as a result of early brain injury.

Association between pre- and perinatal exposures and Tourette syndrome or chronic tic disorder in the ALSPAC cohort

BACKGROUND

Tourette syndrome and chronic tic disorder are heritable but aetiologically complex. Although environment plays a role in their development, existing studies of non-genetic risk factors are inconsistent.

AIMS

To examine the association between pre- and perinatal exposures and Tourette syndrome/chronic tic disorder in the Avon Longitudinal Study of Parents and Children (ALSPAC) prospective longitudinal pre-birth cohort.

METHOD

Relationships between exposures and Tourette syndrome/chronic tic disorder were examined in 6090 children using logistic regression.

RESULTS

Maternal alcohol and cannabis use, inadequate maternal weight gain and parity were associated with Tourette syndrome or Tourette syndrome/chronic tic disorder. Other previously reported exposures, including birth weight and prenatal maternal smoking, were not associated with Tourette syndrome/chronic tic disorder.

CONCLUSIONS

This study supports previously reported relationships between Tourette syndrome/chronic tic disorder and prenatal alcohol exposure, and identifies additional previously unexplored potential prenatal risk factors.

Perinatal problems and psychiatric comorbidity among children with ADHD

Among two large, independent samples of girls with attention-deficit/hyperactivity disorder (ADHD), we examined associations between specific (maternal gestational smoking and drug use, early labor, low birth weight, and infant breathing problems at birth) and cumulative prenatal and perinatal risk factors and psychiatric comorbidity during childhood. Data from the (a) Multimodal Treatment Study of Children with ADHD, a randomized clinical trial with 579 children aged 7 to 9.9 years with combined-type ADHD, and the (b) Berkeley Girls ADHD Longitudinal Sample, a naturalistic study of 140 girls with ADHD (93 combined-type and 47 inattentive-type) who were first seen when they were 6 to 12 years old, were analyzed separately. In each sample, perinatal risk factors were assessed retrospectively by maternal report, and current childhood psychiatric comorbidity was assessed using maternal report on the Diagnostic Interview Schedule for Children. Consistent findings across these two studies show that infant breathing problems, early labor, and total perinatal problems predicted childhood comorbid depression but not comorbid anxiety or externalizing disorders. These associations remained significant, in both samples, with control of family socioeconomic status (SES) and maternal symptoms of ADHD and depression. Results attenuated slightly with control of the number of child comorbidities plus SES and maternal symptoms. Accumulating evidence suggests that perinatal risk factors are important precursors of childhood psychiatric comorbidity and that the association between these risk factors and detrimental psychiatric outcomes cannot be explained by maternal psychiatric symptoms or SES during childhood.

Perinatal problems and psychiatric comorbidity among children with ADHD

Among two large, independent samples of girls with attention-deficit/hyperactivity disorder (ADHD), we examined associations between specific (maternal gestational smoking and drug use, early labor, low birth weight, and infant breathing problems at birth) and cumulative prenatal and perinatal risk factors and psychiatric comorbidity during childhood. Data from the (a) Multimodal Treatment Study of Children with ADHD, a randomized clinical trial with 579 children aged 7 to 9.9 years with combined-type ADHD, and the (b) Berkeley Girls ADHD Longitudinal Sample, a naturalistic study of 140 girls with ADHD (93 combined-type and 47 inattentive-type) who were first seen when they were 6 to 12 years old, were analyzed separately. In each sample, perinatal risk factors were assessed retrospectively by maternal report, and current childhood psychiatric comorbidity was assessed using maternal report on the Diagnostic Interview Schedule for Children. Consistent findings across these two studies show that infant breathing problems, early labor, and total perinatal problems predicted childhood comorbid depression but not comorbid anxiety or externalizing disorders. These associations remained significant, in both samples, with control of family socioeconomic status (SES) and maternal symptoms of ADHD and depression. Results attenuated slightly with control of the number of child comorbidities plus SES and maternal symptoms. Accumulating evidence suggests that perinatal risk factors are important precursors of childhood psychiatric comorbidity and that the association between these risk factors and detrimental psychiatric outcomes cannot be explained by maternal psychiatric symptoms or SES during childhood.

Tourette syndrome and other tic disorders of childhood

Tourettte syndrome (TS) is a common, childhood onset neuropsychiatric disorder consisting of multiple motor and one or more vocal tics which persist for more than 1 year. Comorbid psychiatric diagnoses are frequent in this patient population, including attention-deficit/hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). Tics can be simple or complex, and have a tendency to change over time. Tics are preceded by a premonitory sensation, wax and wane in frequency, and are often exacerbated by stress or excitement. Tic severity usually peaks in childhood, and improves in early adulthood. TS is a highly heritable disorder with a polygenic inheritance. The fundamental pathophysiology of TS is not known, although existing evidence suggests that it involves dysfunction of the basal ganglia and frontal cortical circuits, as well as dopaminergic neurotransmission. Treatment of TS involves consideration of symptom severity and comorbidity. In general, comorbid ADHD and OCD lead to greater disability in these patients, and therefore are the initial treatment priority. As treatment for tics does not alter the natural history of the disorder, it is only recommended if the tics are causing disability. Effective treatments to suppress tics include α-adrenergic agonists and antipsychotic medications.

Update on attention-deficit/hyperactivity disorder and tic disorders: a review of the current literature

Tic disorders impact quality of life, but when they are co-occurring with attention-deficit/hyperactivity disorder, the combined impact takes a toll on psychosocial functioning and adds another layer of complexity to treatment approaches. A review of the current literature supports evidence of a unique relationship between comorbid attention-deficit/hyperactivity disorder and tic disorders, emphasizing the intricate phenotype and impairment associated with these co-occurring conditions. The complexity of these symptoms requires careful diagnosis and appropriate treatment as determined by the level of impairment and can include pharmacotherapy, behavioral interventions, or a combination of therapies. To achieve the greatest benefits in improving quality of life and eliminating further comorbidity, an ideal treatment plan would include a comprehensive evaluation as well as a hierarchical treatment approach involving education of the child, family, and teachers; careful medication management; and cognitive and behavioral training.

Is there an increased risk for drug treated attention deficit/hyperactivity disorder in children born after in vitro fertilization?

BACKGROUND

There is mounting evidence that children born after in vitro fertilization (IVF) run an increased risk of neurological complications and notably cerebral palsy. Whether developmental disturbances occur more often than expected is debated.

AIM

To investigate the risk for ADHD in children conceived after IVF.

METHODS

Children conceived after IVF and born between 1982 and 2005 were identified from all IVF clinics in Sweden. Children who developed attention deficit/hyperactivity disorder (ADHD) were identified with the use of a register over all prescribed drugs in Sweden, using prescriptions for methylphenidate or atomixetine as indicators of ADHD. Maternal and neonatal characteristics were obtained by linkage with the Medical Birth Register and relevant confounders were adjusted for using Mantel-Haenszel procedures. We studied 28 158 children born after IVF and compared them with 2 417 886 children in the population.

RESULTS

After adjustment for year of birth, maternal age, parity, smoking, BMI, and maternal education and after exclusion of women who did not cohabit, a weak but statistically significant association was found with an odds ratio=1.18, 95% confidence interval 1.03-1.36. The effect was stronger in girls (OR=1.40) than boys (OR=1.11) but this difference could be random. After adjustment for length of involuntary childlessness, the OR decreased slightly and lost statistical significance.

CONCLUSIONS

The study suggests a weak association between IVF and drug treated ADHD.

Pediatric autoimmune neuropsychiatric disorders associated with Streptococcus in identical siblings

Termed pediatric autoimmune neuropsychiatric disorders associated with Streptococcus (PANDAS), these cases of childhood-onset obsessive compulsive disorder and tic disorders resemble the presentation of Sydenham chorea, in that they have an acute onset following a group A beta-hemolytic streptococcal infection (group A Streptococcus), with accompanying neurological signs, and an episodic or sawtooth course. Familial associations of this subgroup of patients remain understudied. This report provides phenotypic descriptions of three youth with PANDAS as well as their genetically identical siblings (in two cases of twins and one case of triplets). These cases highlight the potential for environmental influences for discordant presentations in genetically identical siblings. Despite identical genetics, presentations showed marked variation across siblings (from a full PANDAS presentation to asymptomatic). Further research into environmentally driven influences such as postinfectious molecular mimicry and epigenetic factors that may influence the manifestation of these pediatric neuropsychiatric disorders will promote our understanding of their prevention and treatment.

The DRD4 gene and severity of tics and comorbid symptoms: main effects and interactions with delivery complications

In this study, we investigated the role of the dopamine receptor D4 (DRD4) 48-base pairs (bp) variable number of tandem repeats (VNTR) and perinatal adversities regarding severity of tics and comorbid symptoms in children with tic disorders. We genotyped 110 children with tics with regard to the 48-bp VNTR and assessed presence of prenatal smoking exposure, and pregnancy and delivery complications by parent questionnaires. We examined associations between 2, 3, 4, and 7 repeat (R) alleles and severity of tics and comorbid obsessive-compulsive, depressive, anxious, and autistic symptoms. Through linear regressions, we investigated whether perinatal adversities and the 2R, 3R, 4R, and 7R alleles would interact with severity ratings of tics or comorbid symptoms as outcome. Presence of a 2R allele was related to more severe obsessive-compulsive symptoms, and presence of a 3R allele to increased severity of autistic features. Pregnancy complications were associated with decreased obsessive-compulsive symptom severity, and prenatal smoking exposure to more severe depressive and autistic symptoms. In children without a 3R allele delivery complications were associated with more severe tics, but in children with a 3R variant an inverse relation between delivery complications and tic severity was found. Moreover, the relation between delivery complications and internalizing symptom severity appeared to be most pronounced in children with a 2R allele. In conclusion, this study provides evidence for a role of the 48-bp VNTR in the etiology of tic and associated disorders, and for interactions with delivery complications regarding severity of tics and co-occurring internalizing symptoms.

Severe psychosocial stress and heavy cigarette smoking during pregnancy: an examination of the pre- and perinatal risk factors associated with ADHD and Tourette syndrome

Attention-deficit/hyperactivity disorder (ADHD) is frequently diagnosed in children with Tourette syndrome (TS). The basis for this co-occurrence is uncertain. This study aimed to determine if specific pre- and perinatal risk factors, including heavy maternal smoking and severe psychosocial stress during pregnancy, were associated with one or both disorders, or neither. We compared maternal report data on pre- and perinatal risk factors on 222 children between the ages of 7 and 18 years including 45 individuals with TS alone, 52 individuals with ADHD alone, 60 individuals with condition of comorbid TS + ADHD, and 65 unaffected control children. Pre- and perinatal histories as well as psychiatric assessments were performed using standardized questionnaires and semi-structured interviews with the mothers and children. Logistic regression was used to determine the odds ratio for each variable of interest. Compared to the mothers of unaffected control children, the mothers of children with ADHD alone reported higher rates of heavy smoking (>10 cigarettes per day) during pregnancy and higher levels of severe psychosocial stress during pregnancy (OR = 13.5, p < 0.01 and OR = 6.8, p < 0.002, respectively). The TS + ADHD and the TS alone patients also had higher rates heavy maternal smoking and high levels of psychosocial stress compared to the control children, but these differences failed to reach statistical significance (heavy smoking: OR = 8.5, p < 0.052, OR = 4.6, p < 0.19, respectively; severe psychosocial stress: OR = 3.1, p < 0.07, OR = 2.6, p < 0.11, respectively). Heavy maternal smoking and severe levels psychosocial stress during pregnancy were independently associated with a diagnosis of ADHD. TS patients also had higher rates of these risk factors, but the ORs failed to reach statistical significance. Efforts are needed to reduce the frequency of these risk factors in high-risk populations. Future studies, using genetically sensitive designs, are also needed to sort out the causal pathways.

Risk factors for stuttering: a secondary analysis of a large data base

The spectrum of risk and concomitant factors in stuttering is generally thought to be wide and heterogeneous. However, only a few studies have examined these factors using information from large databases. We examined the data on 11,905 Swiss conscripts from 2003. All cases with high psychiatric screening scores indicating "caseness" for a psychiatric disorder were excluded, among them potential malingerers, so that 9,814 records remained. The analyses rely on self-reported information about stuttering in childhood, problems at birth, problems in school, mental disorders of parents and relatives, childhood adversity and socio-demographic information. Statistical modelling was done using logistic regression and path analysis models. Risk factors determined in the logistic regression include premature birth, probable attention deficit hyperactive disorder, alcohol abuse of the parents, obsessive-compulsive disorder in parents and relatives, having a disabled mother and having a parent from a foreign country. There is no overwhelmingly strong risk factor; all odds ratios are about 2 or below. In conclusion, large databases are helpful in revealing less obvious and less frequent risk factors for heterogeneous disorders such as stuttering. Obviously, not only secondary analyses, but also systematical large scale studies would be required to complete the complex epidemiological puzzle in stuttering. An extensive examination of young adults who were initially assessed in childhood might provide the most promising design.

Role of perinatal adversities on tic severity and symptoms of attention deficit/hyperactivity disorder in children and adolescents with a tic disorder

OBJECTIVE

To investigate the role of perinatal adversities with regard to tic severity and comorbid attention deficit/hyperactivity disorder (ADHD) symptoms in children with a tic disorder.

METHODS

In 75 children and adolescents with a tic disorder, we retrospectively assessed presence of pregnancy, delivery, and postnatal complications and of prenatal exposure to smoking and alcohol. Children with and without these perinatal adversities were compared regarding tic and ADHD symptom severity. Furthermore, through linear regressions, we investigated whether perinatal adversities would interact with presence in first-degree relatives of tic or any mental disorders with the tic or ADHD measure as outcome.

RESULTS

Presence of delivery complications was related to tic severity and prenatal smoking exposure to severity of comorbid ADHD symptoms. The relationship between smoking exposure in utero and ADHD symptom severity appeared to be more pronounced in children with a positive family history of mental disorders.

CONCLUSION

This study provides evidence of a role for perinatal adversities in the etiology of tic disorders. Children with perinatal adversities may be vulnerable to develop more severe tics or comorbid ADHD symptoms in the presence of a positive family history of mental disorders, suggesting a role for gene-environment interactions.