Developmental associations between traits of autism spectrum disorder and attention deficit hyperactivity disorder: a genetically informative, longitudinal twin study

Diagnostic trajectories of mental disorders in children and adolescents: a cohort study

Mental disorders in children and adolescents may follow different trajectories, such as remission, change of diagnosis, or addition of two or more comorbid diagnoses, showing a heterotypic pattern. This study aims to describe the main diagnostic trajectories across a broad range of mental disorder diagnostic categories, from childhood to adolescence and from adolescence to young adulthood in a clinical population. A prospective study was conducted among a clinical sample of children and adolescents who were aged 3-17 years at the face-to-face baseline interview. Electronic health records of these participants were reviewed 10 years later. The diagnostic stability over time was examined using the kappa coefficient, and factors associated with stability were explored using simple logistic regression. The study included a sample of 691 participants. The kappa coefficient for diagnostic stability across all diagnoses was 0.574 for the transition from childhood to adulthood, 0.614 from childhood to adolescence, and 0.733 from adolescence to adulthood. Neurodevelopmental diagnoses had the highest stability. Factors associated with higher diagnostic stability included family history of mental disorders, receiving psychopharmacological treatment, and symptom severity at baseline. We found a variable diagnostic stability across different diagnoses and age categories. The different life transitions represent complex periods that should not be overlooked from a clinical standpoint. An appropriate transition from child and adolescent mental health services to adult mental health services may have a positive impact on children and adolescents with mental disorders.

Three year outcomes in infants with a family history of autism and/or attention deficit hyperactivity disorder

Background

Most research on early outcomes in infants with a family history (FH) of autism has focussed on categorically defined autism, although some have language and developmental delays. Less is known about outcomes in infants with a FH of attention deficit hyperactivity disorder (ADHD).

Methods

Infants with and without a FH of autism and/or ADHD, due to a first-degree relative with either or both conditions, were recruited at 5 or 10 months. Three year outcomes were characterised using latent profile analysis (LPA) across measures of cognitive ability, adaptive functioning and autism, ADHD and anxiety traits (n = 131). We additionally ran an LPA using only autism and ADHD measures, and the broader LPA in an independent cohort (n = 139) and in both cohorts combined (n = 270).

Results

A Low Developmental Level + High Behavioural Concerns class had elevated autism, ADHD and anxiety scores, low cognitive and adaptive function, and included all but one child with autism. A Low Developmental Level + Typical Behaviour class had average cognitive ability and typical behaviour but low adaptive function. A Typical Developmental Level + Some Behavioural Concerns class had average cognitive and adaptive function but slightly elevated behaviour scores. A High Developmental Level + Typical Behaviour class had above average cognitive ability and typical behaviour. All four LPAs identified classes characterised by combinations of either, or both, Low Development Level and elevated behaviour scores, as well as a typically developing class. No classes had elevated autism or ADHD traits in isolation.

Conclusions

Some infants with a FH of autism or ADHD have atypical developmental and behavioural outcomes, but do not show strong autism or ADHD traits in isolation. The field needs to recalibrate aims and methods to embrace the broader transdiagnostic pattern of outcomes seen in these infants.

Comorbidity and Characteristics of Autism Spectrum Disorders and ADHD in Children: A Clinically-Based Study

OBJECTIVE

We examined the characteristics and heritability of Autism Spectrum Disorder (ASD) and ADHD through a twin study.

METHOD

Our sample included 44 twins, with at least one twin diagnosed with ASD. Among the participants, 30 had ASD, and 18 of them also had coexisting ADHD.

RESULTS

We observed higher concordance rates for ASD in monozygotic twins compared to dizygotic twins (67% vs. 25%), indicating a genetic influence on ASD. Inattentive symptoms of ADHD were more prevalent in monozygotic twins. The ASD + ADHD group exhibited significantly higher Social Responsiveness Scale scores, indicating greater social difficulties compared to the ASD and typical development groups. Twin analyses revealed that shared genetic factors accounted for 72.25% of the variance in both ASD and ADHD symptoms.

CONCLUSIONS

Our findings suggest that the comorbidity of ASD and ADHD may indicate increased severity and can be explained by shared genetic factors underlying both conditions.

Discordant associations of educational attainment with ASD and ADHD implicate a polygenic form of pleiotropy

Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) are complex co-occurring neurodevelopmental conditions. Their genetic architectures reveal striking similarities but also differences, including strong, discordant polygenic associations with educational attainment (EA). To study genetic mechanisms that present as ASD-related positive and ADHD-related negative genetic correlations with EA, we carry out multivariable regression analyses using genome-wide summary statistics (N = 10,610-766,345). Our results show that EA-related genetic variation is shared across ASD and ADHD architectures, involving identical marker alleles. However, the polygenic association profile with EA, across shared marker alleles, is discordant for ASD versus ADHD risk, indicating independent effects. At the single-variant level, our results suggest either biological pleiotropy or co-localisation of different risk variants, implicating MIR19A/19B microRNA mechanisms. At the polygenic level, they point to a polygenic form of pleiotropy that contributes to the detectable genome-wide correlation between ASD and ADHD and is consistent with effect cancellation across EA-related regions.

Combining multivariate genomic approaches to elucidate the comorbidity between autism spectrum disorder and attention deficit hyperactivity disorder

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are two highly heritable neurodevelopmental disorders. Several lines of evidence point towards the presence of shared genetic factors underlying ASD and ADHD. We conducted genomic analyses of common risk variants (i.e. single nucleotide polymorphisms, SNPs) shared by ASD and ADHD, and those specific to each disorder.

METHODS

With the summary data from two GWAS, one on ASD (N = 46,350) and another on ADHD (N = 55,374) individuals, we used genomic structural equation modelling and colocalization analysis to identify SNPs shared by ASD and ADHD and SNPs specific to each disorder. Functional genomic analyses were then conducted on shared and specific common genetic variants. Finally, we performed a bidirectional Mendelian randomization analysis to test whether the shared genetic risk between ASD and ADHD was interpretable in terms of reciprocal relationships between ASD and ADHD.

RESULTS

We found that 37.5% of the SNPs associated with ASD (at p < 1e-6) colocalized with ADHD SNPs and that 19.6% of the SNPs associated with ADHD colocalized with ASD SNPs. We identified genes mapped to SNPs that are specific to ASD or ADHD and that are shared by ASD and ADHD, including two novel genes INSM1 and PAX1. Our bidirectional Mendelian randomization analyses indicated that the risk of ASD was associated with an increased risk of ADHD and vice versa.

CONCLUSIONS

Using multivariate genomic analyses, the present study uncovers shared and specific genetic variants associated with ASD and ADHD. Further functional investigation of genes mapped to those shared variants may help identify pathophysiological pathways and new targets for treatment.

Familial and genetic associations between autism spectrum disorder and other neurodevelopmental and psychiatric disorders

BACKGROUND

Familial and genetic associations between autism spectrum disorder (ASD) and other neurodevelopmental and psychiatric disorders have been reported, sometimes with conflicting results. We estimated familial and genetic associations between ASD and nine disorder groups, and explored differences in these associations for ASD in the context of intellectual disability, epilepsy, chromosomal abnormalities, and congenital malformations.

METHODS

Individuals born between 1985 and 2009 living in Sweden on their seventh birthday were linked to their biological parents in order to identify different types of relatives. We retrieved information on all the disorders considered from the National Patient Register. Logistic regression was used to estimate the familial association between ASD and other neurodevelopmental and psychiatric disorders in the different groups of relatives. Structural equation modeling was used to estimate phenotypic (r_p ) and genetic associations (r_g ), as well as the contribution of genetic influences to r_p .

RESULTS

The study included 2,398,608 individuals. Among relatives of individuals diagnosed with ASD, there was an increased risk of the disorders considered, compared to relatives of individuals who were not diagnosed with ASD. Stronger associations were detected for ASD without any additional diagnosis of intellectual disability, epilepsy, chromosomal abnormalities, and congenital malformations. The strongest genetic correlation was estimated between ASD and other neurodevelopmental disorders (r_g  = 0.73; 95% CI = 0.66-0.79). Moderate genetic correlations were estimated for anxiety disorders (r_g  = 0.47; 95% CI = 0.33-0.61), depression (r_g  = 0.52; 95% CI = 0.37-0.66), and intentional self-harm (r_g  = 0.54; 95% CI = 0.36-0.71).

CONCLUSIONS

ASD shows familial and genetic association not only with other neurodevelopmental disorders, but also with other psychiatric disorders, such as anxiety, depression, and intentional self-harm. Family history of ASD comorbid with intellectual disability, epilepsy, congenital malformations, or chromosomal abnormalities is less related to other psychiatric disorders, potentially suggesting a different etiology for this subgroup of patients.

Hyperacusis in Autism Spectrum Disorders

Hyperacusis is highly prevalent in the autism spectrum disorder (ASD) population. This auditory hypersensitivity can trigger pragmatically atypical reactions that may impact social and academic domains. Objective: The aim of this report is to describe the relationship between decreased sound tolerance disorders and the ASD population. Topics covered: The main topics discussed include (1) assessment and prevalence of hyperacusis in ASD; (2) etiology of hyperacusis in ASD; (3) treatment of hyperacusis in ASD. Conclusions: Knowledge of the assessment and treatment of decreased sound tolerance disorders within the ASD population is growing and changing.

Examining the association between childhood autistic traits and adolescent hypomania: a longitudinal twin study

BACKGROUND

There is evidence that autism spectrum disorders (ASDs) co-occur with bipolar disorder (BD) relatively frequently. Individuals with BD often report symptoms of mania and hypomania during adolescence, prior to the age of onset for BD. It is unknown whether these symptoms are associated with ASDs. We examined whether diagnoses of ASDs and autistic traits were associated with hypomania in a large, population-based Swedish twin sample.

METHODS

Parental structured interviews assessed autistic traits, and were used to assign screening diagnoses of ASDs, when twins were aged 9 or 12 (N = 13 533 pairs). Parents then completed questionnaires assessing hypomania when the twins were aged 15 and 18 (N = 3852 pairs at age 15, and 3013 pairs at age 18). After investigating the phenotypic associations between these measures, we used the classical twin design to test whether genetic and environmental influences on autistic traits influence variation in adolescent hypomania.

RESULTS

Autistic traits and ASD diagnoses in childhood were associated with elevated scores on the measures of adolescent hypomania. Twin analyses indicated that 6-9% of the variance in hypomania was explained by genetic influences that were shared with autistic traits in childhood. When repeating these analyses for specific autistic trait domains, we found a stronger association between social interaction difficulties and hypomania than for other autistic trait domains.

CONCLUSIONS

These results indicate a genetic link between autistic traits and hypomania in adolescence. This adds to the growing evidence base of genetic factors associated with ASDs showing links with psychiatric outcomes across childhood and into adulthood.

CD103 Deficiency Promotes Autism (ASD) and Attention-Deficit Hyperactivity Disorder (ADHD) Behavioral Spectra and Reduces Age-Related Cognitive Decline

The incidence of autism spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD), which frequently co-occur, are both rising. The causes of ASD and ADHD remain elusive, even as both appear to involve perturbation of the gut-brain-immune axis. CD103 is an integrin and E-cadherin receptor most prominently expressed on CD8 T cells that reside in gut, brain, and other tissues. CD103 deficiency is well-known to impair gut immunity and resident T cell function, but it's impact on neurodevelopmental disorders has not been examined. We show here that CD8 T cells influence neural progenitor cell function, and that CD103 modulates this impact both directly and potentially by controlling CD8 levels in brain. CD103 knockout (CD103KO) mice exhibited a variety of behavioral abnormalities, including superior cognitive performance coupled with repetitive behavior, aversion to novelty and social impairment in females, with hyperactivity with delayed learning in males. Brain protein markers in female and male CD103KOs coincided with known aspects of ASD and ADHD in humans, respectively. Surprisingly, CD103 deficiency also decreased age-related cognitive decline in both sexes, albeit by distinct means. Together, our findings reveal a novel role for CD103 in brain developmental function, and identify it as a unique factor linking ASD and ADHD etiology. Our data also introduce a new animal model of combined ASD and ADHD with associated cognitive benefits, and reveal potential therapeutic targets for these disorders and age-related cognitive decline.

Mapping associations between polygenic risks for childhood neuropsychiatric disorders, symptoms of attention deficit hyperactivity disorder, cognition, and the brain

There are now large-scale data on which common genetic variants confer risk for attention deficit hyperactivity disorder (ADHD). Here, we use mediation analyses to explore how cognitive and neural features might explain the association between common variant (polygenic) risk for ADHD and its core symptoms. In total, 544 participants participated (mean 21 years, 212 (39%) with ADHD), most with cognitive assessments, neuroanatomic imaging, and imaging of white matter tract microstructure. We found that polygenic risk for ADHD was associated with symptoms of hyperactivity-impulsivity but not inattention. This association was mediated across multiple PRS thresholds by white matter microstructure, specifically by axial diffusivity of the right corona radiata, (maximum indirect effect β = -0.034 (CI: -0.065 to -0.01), by thickness of the left dorsomedial prefrontal (β = -0.029; CI: -0.061 to -0.0047) and area of the right lateral temporal cortex (β = 0.024; CI: 0.0034-0.054). In addition, modest serial mediation was found, mapping a pathway from polygenic risk, to white matter microstructure of the anterior corona radiata, then cognition (working memory, focused attention), and finally to hyperactivity-impulsivity (working memory β = -0.014 (CI: -0.038 to -0.0026); focused attention β = -0.011 (CI: -0.033 to -0.0017). These mediation pathways were diagnostically specific and were not found for polygenic risk for ASD or schizophrenia. In conclusion, using a deeply phenotyped cohort, we delineate a pathway from polygenic risk for ADHD to hyperactive-impulsive symptoms through white matter microstructure, cortical anatomy, and cognition.

Disentangling autism spectrum and attention-deficit/hyperactivity symptoms over development in fragile X syndrome

Even genetic disorders associated with monogenic aetiologies are characterized by complex and variable risk for poor outcomes, highlighting the need to follow trajectories longitudinally. Here, we investigated the longitudinal relationships between attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) symptoms in a population at high risk for both: boys with fragile X syndrome. 59 boys with fragile X syndrome aged 3-10 years old at entry participated in this study, and were followed up one and two years after their first visit. As expected, we found strong relationships over three timepoints for ADHD symptoms (as measured by the parent-rated Conners scale) and ASD symptoms (as measured by the Social Communication Questionnaire [SCQ]). In addition, using structural equation modeling (SEM) we found that ADHD symptoms at time 2 predicted ASD symptoms at time 3, suggestive of a causal relationship. Importantly, these relationships hold when including chronological age at entry to the study, as well as when including severity of impairment as measured by IQ, and their effects on both ASD and ADHD symptoms do not reach significance. This result highlights the need to study outcomes longitudinally and it informs the comorbidity of the two symptom domains in FXS as well as their potential directionality, both of which have been little researched. In addition, our findings may suggest a future need to study how ADHD symptoms and their treatment impact individuals with ASD.

Zonulin-Dependent Intestinal Permeability in Children Diagnosed with Mental Disorders: A Systematic Review and Meta-Analysis

Worldwide, up to 20% of children and adolescents experience mental disorders, which are the leading cause of disability in young people. Research shows that serum zonulin levels are associated with increased intestinal permeability (IP), affecting neural, hormonal, and immunological pathways. This systematic review and meta-analysis aimed to summarize evidence from observational studies on IP in children diagnosed with mental disorders. The review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A systematic search of the Cochrane Library, PsycINFO, PubMed, and the Web of Science identified 833 records. Only non-intervention (i.e., observational) studies in children (<18 years) diagnosed with mental disorders, including a relevant marker of intestinal permeability, were included. Five studies were selected, with the risk of bias assessed according to the Newcastle–Ottawa scale (NOS). Four articles were identified as strong and one as moderate, representing altogether 402 participants providing evidence on IP in children diagnosed with attention deficit and hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and obsessive–compulsive disorder (OCD). In ADHD, elevated serum zonulin levels were associated with impaired social functioning compared to controls. Children with ASD may be predisposed to impair intestinal barrier function, which may contribute to their symptoms and clinical outcome compared to controls. Children with ASD, who experience gastro-intestinal (GI) symptoms, seem to have an imbalance in their immune response. However, in children with OCD, serum zonulin levels were not significantly different compared to controls, but serum claudin-5, a transmembrane tight-junction protein, was significantly higher. A meta-analysis of mean zonulin plasma levels of patients and control groups revealed a significant difference between groups (p = 0.001), including the four studies evaluating the full spectrum of the zonulin peptide family. Therefore, further studies are required to better understand the complex role of barrier function, i.e., intestinal and blood–brain barrier, and of inflammation, to the pathophysiology in mental and neurodevelopmental disorders. This review was PROSPERO preregistered, (162208).

Early Origins of Autism Comorbidity: Neuropsychiatric Traits Correlated in Childhood Are Independent in Infancy

Previous research has suggested that behavioral comorbidity is the rule rather than the exception in autism. The present study aimed to trace the respective origins of autistic and general psychopathologic traits-and their association-to infancy. Measurements of autistic traits and early liability for general psychopathology were assessed in 314 twins at 18 months, ascertained from the general population using birth records. 222 twins were re-evaluated at 36 months. Standardized ratings of variation in social communication at 18 months were highly heritable and strongly predicted autistic trait scores at 36 months. These early indices of autistic liability were independent from contemporaneous ratings of behavior problems on the Brief Infant-Toddler Social and Emotional Assessment (which were substantially environmentally-influenced), and did not meaningfully predict internalizing or externalizing scores on the Achenbach Scales of Empirically Based Assessment at 36 months. In this general population infant twin study, variation in social communication was independent from variation in other domains of general psychopathology, and exhibited a distinct genetic structure. The commonly-observed comorbidity of specific psychiatric syndromes with autism may arise from subsequent interactions between autistic liability and independent susceptibilities to other psychopathologic traits, suggesting opportunities for preventive amelioration of outcomes of these interactions over the course of development.

The nature and nurture of ADHD and its comorbidities: A narrative review on twin studies

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in children worldwide, and also the recognition of its persistence into adulthood is increasing. While ADHD in childhood is highly heritable and mostly driven by familial factors, during adulthood it appears to show a lower heritability, even if there is not total agreement on this yet. This disorder often co-occurs with many other conditions, which also vary across the different stages of development, and several studies have used the twin design to investigate these comorbidities, giving valuable insights into the origins of the observed co-occurrence. This review aims to summarize the main results of twin research, according to the following domains: individual traits, cognitive impairment, behavioral manifestations, clinical conditions and psychosocial risk factors. Individual features seem to play a role in this symptomatology and include personality traits such as negative emotionality, personality disorders and temperamental dimensions with a predominance of novelty seeking. At a lower level, ADHD is associated with both functional and anatomic brain characteristics. ADHD is also associated with some forms of cognitive impairment, such as sluggish cognitive tempo, and learning disabilities, with a specific predisposition to reading disability. In addition, ADHD is strongly associated with externalizing disorders such as conduct disorder and oppositional defiant disorder, and some behavioral outcomes, particularly substance use and abuse both in adolescence and adulthood. Moreover, ADHD symptoms often overlap with other psychological disorders, namely affective and internalizing disorders, as well as autism spectrum disorder and autistic-like traits in a wider sense. Notably, a genetic overlap has been found between asthma and ADHD, particularly with respect to hyperactivity/impulsivity dimensions. ADHD also appears to represent a risk factor for disordered eating, and, more specifically, for binge eating and bulimia nervosa. Finally, among psychosocial factors, an association has been proposed between childhood maltreatment and ADHD symptoms.

Early developmental pathways to childhood symptoms of attention-deficit hyperactivity disorder, anxiety and autism spectrum disorder

BACKGROUND

Children with autism spectrum disorder (ASD) often have co-occurring symptoms of attention-deficit/hyperactivity disorder (ADHD) and/or anxiety. It is unclear whether these disorders arise from shared or distinct developmental pathways. We explored this question by testing the specificity of early-life (infant and toddler) predictors of mid-childhood ADHD and anxiety symptoms compared to ASD symptoms.

METHODS

Infants (n = 104) at high and low familial risk for ASD took part in research assessments at 7, 14, 24 and 38 months, and 7 years of age. Symptoms of ASD, ADHD and anxiety were measured by parent report at age 7. Activity levels and inhibitory control, also measured by parent report, in infancy and toddlerhood were used as early-life predictors of ADHD symptoms. Fearfulness and shyness measured in infancy and toddlerhood were used as early-life predictors of anxiety symptoms. Correlations and path analysis models tested associations between early-life predictors and mid-childhood ADHD and anxiety symptoms compared to mid-childhood ASD symptoms, and the influence of controlling for ASD symptoms on those associations.

RESULTS

Increased activity levels and poor inhibitory control were correlated with ADHD symptoms and not ASD or anxiety; these associations were unchanged in path models controlling for risk-group and ASD symptoms. Increased fearfulness and shyness were correlated with anxiety symptoms, but also ASD symptoms. When controlling for risk-group in path analysis, the association between shyness and anxiety became nonsignificant, and when further controlling for ASD symptoms the association between fearfulness and anxiety became marginal.

CONCLUSIONS

The specificity of early-life predictors to ADHD symptoms suggests early developmental pathways to ADHD might be distinct from ASD. The overlap in early-life predictors of anxiety and ASD suggests that these disorders are difficult to differentiate early in life, which could reflect the presence of common developmental pathways or convergence in early behavioural manifestations of these disorders.

Infant regulatory function acts as a protective factor for later traits of autism spectrum disorder and attention deficit/hyperactivity disorder but not callous unemotional traits

Background

Reduced executive functions (EF) are commonly associated with developmental conditions (e.g., autism spectrum disorder, ASD; attention deficit/hyperactivity disorder, ADHD), although EF seems to be typical in children with callous unemotional (CU) traits. Regulatory function (RF) is a proposed infant precursor that maps on onto factors driving later EF. Here, we first test whether RF is specifically and negatively associated with ASD and ADHD traits, but not CU traits. Second, we test whether RF can act as a protective factor, by moderating the association between infant markers and subsequent ASD and ADHD traits.

Methods

Participants were 79 infants at high (N = 42) and low (N = 37) familial risk for ASD. Data come from the 14-month infant visit (Autism Observational Scale for Infants; AOSI; activity level and RF from the Infant Behavior Questionnaire; IBQ) and the 7-year visit (ASD traits: Social Responsiveness Scale, SRS; ADHD traits: Conners 3, CU traits: Inventory of Callous Unemotional Traits).

Results

Infant RF was negatively associated with later traits of ASD (B = − 0.5, p = 0.01) and ADHD inattention (B = − 0.24, p = 0.02) but not hyperactivity (B = − 0.25, p = 0.10) or CU traits (B = 0.02, p = 0.86). RF moderated the association between infant AOSI score and ASD traits, with a significant effect in those with low RF (B = 0.10, p = 0.006), not high RF (B = 0.01, p = 0.78). Similarly, for ADHD, infant activity level was associated with later ADHD inattention in those with low (B = 0.17, p = 0.04) but not high RF (B = 0.07, p = 0.48). For ADHD hyperactivity symptoms, activity level was predictive at both high and low levels of RF.

Conclusions

Strong RF may allow children to compensate for other atypicalities, thus attenuating the association between infant markers and later disorder traits. Whilst infant RF was associated with both ASD and ADHD inattention traits, there was no association with ADHD hyperactivity or CU traits. This suggests that any protective effect may not be universal and emphasises the need for a better understanding of the underlying moderating mechanisms.

Electronic supplementary material

The online version of this article (10.1186/s11689-019-9274-0) contains supplementary material, which is available to authorized users.

Using genetic data to strengthen causal inference in observational research

Causal inference is essential across the biomedical, behavioural and social sciences.By progressing from confounded statistical associations to evidence of causal relationships, causal inference can reveal complex pathways underlying traits and diseases and help to prioritize targets for intervention. Recent progress in genetic epidemiology - including statistical innovation, massive genotyped data sets and novel computational tools for deep data mining - has fostered the intense development of methods exploiting genetic data and relatedness to strengthen causal inference in observational research. In this Review, we describe how such genetically informed methods differ in their rationale, applicability and inherent limitations and outline how they should be integrated in the future to offer a rich causal inference toolbox.

Genetic and environmental contribution to the overlap between ADHD and ASD trait dimensions in young adults: a twin study

BACKGROUND

Traits of attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are strongly associated in children and adolescents, largely due to genetic factors. Less is known about the phenotypic and aetiological overlap between ADHD and ASD traits in adults.

METHODS

We studied 6866 individuals aged 20-28 years from the Swedish Study of Young Adult Twins. Inattention (IA) and hyperactivity/impulsivity (HI) were assessed using the WHO Adult ADHD Self-Report Scale-V1.1. Repetitive and restricted behaviours (RRB) and social interaction and communication (SIC) were assessed using the Autism-Tics, ADHD, and other Comorbidities inventory. We used structural equation modelling to decompose covariance between these ADHD and ASD trait dimensions into genetic and shared/non-shared environmental components.

RESULTS

At the phenotypic level, IA was similarly correlated with RRB (r = 0.33; 95% Confidence Interval (CI) 0.31-0.36) and with SIC (r = 0.32; 95% CI 0.29-0.34), whereas HI was more strongly associated with RRB (r = 0.38; 95% CI 0.35-0.40) than with SIC (r = 0.24; 95% CI 0.21-0.26). Genetic and non-shared environmental effects accounted for similar proportions of the phenotypic correlations, whereas shared environmental effects were of minimal importance. The highest genetic correlation was between HI and RRB (r = 0.56; 95% 0.46-0.65), and the lowest was between HI and SIC (r = 0.33; 95% CI 0.23-0.43).

CONCLUSIONS

We found evidence for dimension-specific phenotypic and aetiological overlap between ADHD and ASD traits in adults. Future studies investigating mechanisms underlying comorbidity between ADHD and ASD may benefit from exploring several symptom-dimensions, rather than considering only broad diagnostic categories.

Association of Fetal Growth With General and Specific Mental Health Conditions

IMPORTANCE

It is unclear if the associations between fetal growth and later mental health conditions remain after controlling for familial factors and psychiatric comorbidity.

OBJECTIVE

To examine the associations between fetal growth and general and specific mental health conditions, controlling for familial factors.

DESIGN, SETTING, AND PARTICIPANTS

This register-based study conducted in Sweden analyzed 546 894 pairs of full siblings born between January 1, 1973, and December 31, 1998. Sibling pairs were followed up through December 31, 2013. First, population-based and within-sibling pair associations (which controlled for time-invariant familial confounders) between fetal growth and the outcomes were estimated. Second, exploratory factor analysis was applied to the outcomes to derive 1 general factor and 4 specific and independent factors. Third, the general and specific factors were regressed on fetal growth. Statistical analysis was performed from March 27, 2017, to October 27, 2018.

MAIN OUTCOME AND MEASURES

The outcomes were 11 psychiatric diagnoses (depression, anxiety, obsessive-compulsive disorder, posttraumatic stress disorder, bipolar disorder, alcohol abuse, drug use, attention-deficit/hyperactivity disorder, autism, schizophrenia, and schizoaffective disorder) and court convictions of violent crimes. Birth weight (in kilograms) statistically adjusted for gestational age was the exposure.

RESULTS

The mean (SD) age of the 1 093 788 participants was 27.2 (6.8) years (range, 15.1-40.9 years) and 51.5% were male. Nine outcomes were significantly associated with birth weight in the population at large: depression (odds ratio [OR], 0.96; 95% CI, 0.95-0.98), anxiety (OR, 0.94; 95% CI, 0.92-0.95), posttraumatic stress disorder (OR, 0.91; 95% CI, 0.89-0.93), bipolar disorder (OR, 0.94; 95% CI, 0.89-1.00), alcohol abuse (OR, 0.89; 95% CI, 0.87-0.91), drug use (OR, 0.83; 95% CI, 0.80-0.85), violent crimes (OR, 0.85; 95% CI, 0.83-0.86), attention-deficit/hyperactivity disorder (OR, 0.88; 95% CI, 0.86-0.90), and autism (OR, 0.95; 95% CI, 0.92-0.97). Only depression (OR, 0.95; 95% CI 0.92-0.98), obsessive-compulsive disorder (OR, 0.93; 95% CI, 0.87-0.99), attention-deficit/hyperactivity disorder (OR, 0.86; 95% CI, 0.82-0.89), and autism (OR, 0.72; 95% CI, 0.69-0.76) remained significantly associated within sibling pairs. An exploratory factor analysis indicated that 1 general and 4 specific factors (capturing anxiety, externalizing, neurodevelopmental, and psychotic conditions) fit the outcomes well. Across almost all sensitivity analyses, an increase in birth weight by 1 kg significantly reduced the general (β, -0.047; 95% CI, -0.071 to -0.023) and the specific neurodevelopmental factors (β, -0.159; 95% CI, -0.190 to -0.128) within sibling pairs.

CONCLUSIONS AND RELEVANCE

Controlling for familial confounders, reduced fetal growth was associated with a small but significant increase in the general factor of psychopathology and a moderate increase in a specific neurodevelopmental factor.

Investigating the childhood symptom profile of community-based individuals diagnosed with attention-deficit/hyperactivity disorder as adults

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is currently defined as a disorder with onset during childhood. Although ADHD occurs in adults as well as children, recent debate has focused on whether adult ADHD represents a continuation of a child-onset disorder or if ADHD may, in at least some cases, have an adult onset. We therefore aimed to test the hypothesis of adult-onset ADHD using a sample born relatively recently (1992-1999) in order to minimize confounding by secular changes in diagnostic practices.

METHODS

We identified 74 individuals with a community diagnosis of ADHD first assigned during adulthood. We also identified individuals with childhood (N = 194) and adolescent (N = 394) community diagnoses of ADHD. These groups were compared with a comparison group (N = 14,474) on their childhood ADHD and neuropsychiatric symptoms, and rate of other psychiatric diagnoses during childhood.

RESULTS

Having an adulthood community diagnosis of ADHD was associated with a mean increase in childhood ADHD symptoms of approximately three times that of the comparison group. Individuals with an adult community diagnosis of ADHD also displayed more autistic traits, motor problems, learning difficulties, tics, and oppositional behavior. Forty two percent of these individuals, compared with 1% of comparison cases, had a psychiatric diagnosis other than ADHD as children. In post-hoc analyses of 21 ADHD cases showing few or no ADHD symptoms in childhood, we were unable to detect any other childhood symptomatology in only nine cases, of whom six were female.

CONCLUSIONS

Our results indicate that alternative explanations for data that appear to show adult onset ADHD, such as sex biases in diagnostic practices, need rigorous testing before adult onset ADHD can be accepted as a valid clinical construct.

Subtyping the Autism Spectrum Disorder: Comparison of Children with High Functioning Autism and Asperger Syndrome

Since Hans Asperger's first description (Arch Psych Nervenkrankh 117:76-136, 1944), through Lorna Wing's translation and definition (Psychol Med 11:115-129, 1981), to its introduction in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM, 1994), Asperger Syndrome has always aroused huge interest and debate, until vanishing in the DSM fifth edition (2013). The debate regarded its diagnostic validity and its differentiation from high functioning autism (HFA). The present study aimed to examine whether AS differed from HFA in clinical profiles and to analyze the impact of DSM-5's innovation. Differences in cognitive, language, school functioning and comorbidities, were revealed when 80 AS and 70 HFA patients (3-18 years) were compared. Results suggested that an AS empirical distinction within autism spectrum disorder should be clinically useful.

Sex-Gender Comparisons in Comorbidities of Children and Adolescents With High-Functioning Autism Spectrum Disorder

Over the last few years, new studies focused their attention on the gender-related features in high-functioning autism spectrum disorder (HFA), often leading to controversial results. Another interesting aspect of these subtype of patients is linked to the complexity of clinical presentation, where besides core symptoms, other co-occurrence disorders may complicate the diagnostic evaluation. Therefore, we retrospectively studied 159 HFA patients, male and female, investigating their comorbidities and to find any gender difference. For each patient, were evaluated the presence/absence, type and gender distribution of psychopathological comorbidities, according to DSM-5 diagnostic criteria. The total sample was divided in 100 male and 59 female patients, age and intelligence quotient matched. In our sample, the psychiatric comorbidities observed were Attention Deficit Hyperactivity Disorder, Anxiety Disorders, Depressive Disorders, Bipolar Disorder, Obsessive-Compulsive Disorder, and Anorexia Nervosa. No statistical significant differences were found between male and female HFA patients comorbidities except for Anorexia Nervosa. In both male and female patients, attention deficit and hyperactivity disorder and anxiety disorders were found in high percentage. In conclusion, our investigation showed that a statistical significant difference of comorbidity between male and female HFA patients was found only for AN diagnosis. However, the question about the distinction between female and male HFA patients remains quite interesting and an open area of research for future studies.

Increased zonulin is associated with hyperactivity and social dysfunctions in children with attention deficit hyperactivity disorder

BACKGROUND

In attention deficit hyperactivity disorder (ADHD), deteriorations of brain gut axis has been shown in previous studies. One area where the most important challenges are seen in ADHD is social functioning. Zonulin is a protein found in the intestinal intraepithelial component; it has been shown that the level of zonulin increases when intestinal permeability is impaired. Changes in intestinal function were shown in ADHD. Zonulin has been shown to be associated with social impairment in children with autism spectrum disorder. In this study, it was aimed to evaluate the relationship between the ADHD symptoms and zonulin in children with ADHD. Secondarily relation of zonulin and difficulties in social functioning was examined in these children.

METHODS

Forty children diagnosed with ADHD and forty-one healthy children similar age and gender to ADHD group and their mothers were included in the study. Children without any chronic systemic immunological or infectious diseases were included in the case and control group. The ADHD symptoms were scored by the DuPaul ADHD scale and the social functioning of the children was assessed by the Social Responsiveness Scale (SRS). Serum zonulin levels were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Children with ADHD had higher serum zonulin levels and were more impaired in social functioning compared to controls. The level of zonulin was independently predicted with hyperactivity symptoms and SRS scores in regression analysis.

CONCLUSION

In this sample of children with ADHD, elevated zonulin levels were associated with increased symptoms of hyperactivity and impairment of social functioning.

Assessing the evidence for shared genetic risks across psychiatric disorders and traits

Genetic influences play a significant role in risk for psychiatric disorders, prompting numerous endeavors to further understand their underlying genetic architecture. In this paper, we summarize and review evidence from traditional twin studies and more recent genome-wide molecular genetic analyses regarding two important issues that have proven particularly informative for psychiatric genetic research. First, emerging results are beginning to suggest that genetic risk factors for some (but not all) clinically diagnosed psychiatric disorders or extreme manifestations of psychiatric traits in the population share genetic risks with quantitative variation in milder traits of the same disorder throughout the general population. Second, there is now evidence for substantial sharing of genetic risks across different psychiatric disorders. This extends to the level of characteristic traits throughout the population, with which some clinical disorders also share genetic risks. In this review, we summarize and evaluate the evidence for these two issues, for a range of psychiatric disorders. We then critically appraise putative interpretations regarding the potential meaning of genetic correlation across psychiatric phenotypes. We highlight several new methods and studies which are already using these insights into the genetic architecture of psychiatric disorders to gain additional understanding regarding the underlying biology of these disorders. We conclude by outlining opportunities for future research in this area.

The familial co-aggregation of ASD and ADHD: a register-based cohort study

Autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur. The presence of a genetic link between ASD and ADHD symptoms is supported by twin studies, but the genetic overlap between clinically ascertained ASD and ADHD remains largely unclear. We therefore investigated how ASD and ADHD co-aggregate in individuals and in families to test for the presence of a shared genetic liability and examined potential differences between low- and high-functioning ASD in the link with ADHD. We studied 1 899 654 individuals born in Sweden between 1987 and 2006. Logistic regression was used to estimate the association between clinically ascertained ASD and ADHD in individuals and in families. Stratified estimates were obtained for ASD with (low-functioning) and without (high-functioning) intellectual disability. Individuals with ASD were at higher risk of having ADHD compared with individuals who did not have ASD (odds ratio (OR)=22.33, 95% confidence interval (CI): 21.77-22.92). The association was stronger for high-functioning than for low-functioning ASD. Relatives of individuals with ASD were at higher risk of ADHD compared with relatives of individuals without ASD. The association was stronger in monozygotic twins (OR=17.77, 95% CI: 9.80-32.22) than in dizygotic twins (OR=4.33, 95% CI: 3.21-5.85) and full siblings (OR=4.59, 95% CI: 4.39-4.80). Individuals with ASD and their relatives are at increased risk of ADHD. The pattern of association across different types of relatives supports the existence of genetic overlap between clinically ascertained ASD and ADHD, suggesting that genomic studies might have underestimated this overlap.

Experiences of an internet-based support and coaching model for adolescents and young adults with ADHD and autism spectrum disorder -a qualitative study

BACKGROUND

There is a great demand for non-medical treatment and support targeting the needs of adolescents and young adults with autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). There is also a lack of qualitative studies providing in-depth insight into these individuals' own experiences within this area. The current study aimed to explore how adolescents and young adults with ADHD, ASD or both experienced taking part in an internet-based support and coaching intervention.

METHODS

Sixteen participants with ASD, ADHD or both who had participated in an 8-week internet-based support and coaching model, were interviewed using semi-structured interviews. Data was analyzed using qualitative content analysis.

RESULTS

Analysis yielded three themes; Deciding to participate, Taking part in the coaching process and The significance of format. Various motives for joining were expressed by participants, such as viewing the technology as familiar and appealing and expecting it to be better suited to their situation. There was also a previously unfulfilled need for support among participants. In deciding to take part in the intervention the coaches' competence and knowledge were considered essential, often in the light of previously negative experiences. Taking part in the coaching process meant feeling reassured by having someone to turn to in view of shared obstacles to seeking and receiving help. The support was used for talking through and receiving advice on matters related to their diagnosis. Findings further revealed appreciation for aspects relating to the format such as communicating through the written word, being in one's own home and an experience of immediacy. Some disadvantages were voiced including incomplete personal interaction and failing technology. There were also suggestions for greater flexibility.

CONCLUSIONS

The in-depth qualitative data obtained from this study suggest that the current model of support and the internet-based format have specific qualities that could play an important role in the support of adolescents and young adults with ADHD and ASD. Although not a replacement for face-to-face interaction, it could be a promising complement or alternative to other support and treatment options.

TRIAL REGISTRATION

"Internet-based Support for Young People with ADHD and Autism - a Controlled Study" retrospectively registered in www.clinicaltrials.gov ( ClinicalTrials.gov Identifier: NCT02300597 ) at 2014-11-10.

Auditory attention in autism spectrum disorder: An exploration of volumetric magnetic resonance imaging findings

Studies have shown that individuals with autism spectrum disorder (ASD) tend to perform significantly below typically developing individuals on standardized measures of attention, even when controlling for IQ. The current study sought to examine within ASD whether anatomical correlates of attention performance differed between those with average to above-average IQ (AIQ group) and those with low-average to borderline ability (LIQ group) as well as in comparison to typically developing controls (TDC). Using automated volumetric analyses, we examined regional volume of classic attention areas including the superior frontal gyrus, anterior cingulate cortex, and precuneus in ASD AIQ (n = 38) and LIQ (n = 18) individuals along with 30 TDC. Auditory attention performance was assessed using subtests of the Test of Memory and Learning (TOMAL) compared among the groups and then correlated with regional brain volumes. Analyses revealed group differences in attention. The three groups did not differ significantly on any auditory attention-related brain volumes; however, trends toward significant size-attention function interactions were observed. Negative correlations were found between the volume of the precuneus and auditory attention performance for the AIQ ASD group, indicating larger volume related to poorer performance. Implications for general attention functioning and dysfunctional neural connectivity in ASD are discussed.

Genetic and environmental contributions to the association between ADHD and affective problems in early childhood-A Swedish population-based twin study

Few twin studies have explored the relative contribution of genetic and environmental factors to the association between attention deficit hyperactivity disorder (ADHD) and affective problems, and no study has focused on preschool children. We used the classical twin design to explore the genetic and environmental overlap between ADHD symptoms and affective problems in preschool children, based on 879 five-year-old twin pairs born in Sweden 2004-2005. Questionnaire-based parent-ratings were used to measure ADHD symptoms and affective problems. A bivariate twin design was used to decompose variance in ADHD and affective problems into genetic and environmental components, and to test the degree to which these components overlapped across the two traits. Our results showed that there was a significant correlation of 0.34 (95% Confidence Interval [CI] 0.29-0.38) between ADHD and affective problems. This correlation was mostly explained by additive genetic factors (64%, 95%CI 37-93%), and to a lesser extent by shared environmental factors (35%, 95%CI 10-59%). Nonshared environmental factors did not contribute to the correlation between ADHD and affective problems (0%, 95%CI -9 to 10%). These findings show that there is a significant association between ADHD and affective problems in preschool children that is mostly explained by genetic influences. This adds important knowledge about the etiology of both ADHD and affective problems by indicating that these phenotypes are linked from as early as preschool years. This also needs to be taken into consideration when diagnosing young children and clinicians should consider assessing both affective problems and ADHD if one is present.

Family therapy for autism spectrum disorders

BACKGROUND

Autism spectrum disorders (ASDs) are characterised by impairments in communication and reciprocal social interaction. These impairments can impact on relationships with family members, augment stress and frustration, and contribute to behaviours that can be described as challenging. Family members of individuals with ASD can experience high rates of carer stress and burden, and poor parental efficacy. While there is evidence to suggest that individuals with ASD and family members derive benefit from psychological interventions designed to reduce stress and mental health morbidity, and enhance coping, most studies to date have targeted the needs of either individuals with ASD, or family members. We wanted to examine whether family (systemic) therapy, aimed at enhancing communication, relationships or coping, is effective for individuals with ASD and their wider family network.

OBJECTIVES

To evaluate the clinical effectiveness and acceptability of family therapy as a treatment to enhance communication or coping for individuals with ASD and their family members. If possible, we will also seek to establish the economic costs associated with family therapy for this clinical population.

SEARCH METHODS

On 16 January 2017 we searched CENTRAL, MEDLINE, Embase, 10 other databases and three trials registers. We also handsearched reference lists of existing systematic reviews and contacted study authors in the field.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs investigating the effectiveness of family therapy for young people or adults with ASD or family members, or both, delivered via any modality and for an unspecified duration, compared with either standard care, a wait-list control, or an active intervention such as an alternative type of psychological therapy.

DATA COLLECTION AND ANALYSIS

Two authors independently screened each title and abstract and all full-text reports retrieved. To enhance rigour, 25% of these were independently screened by a third author.

MAIN RESULTS

The search yielded 4809 records. Of these, we retrieved 37 full-text reports for further scrutiny, which we subsequently excluded as they did not meet the review inclusion criteria, and identified one study awaiting classification.

AUTHORS' CONCLUSIONS

Few studies have examined the effectiveness of family therapy for ASD, and none of these are RCTs. Further research studies employing methodologically robust trial designs are needed to establish whether family therapy interventions are clinically beneficial for enhancing communication, strengthening relationships, augmenting coping and reducing mental health morbidity for individuals with ASD and family members.

The central nervous system patterning gene variants associated with clinical symptom severity of autism spectrum disorders

BACKGROUND/PURPOSE

Central nervous system (CNS) patterning genes are recognized as candidate genes for autism spectrum disorders (ASDs) based on neuroimaging and neuropathological evidence. Several genes that regulate CNS development are shown to be associated with ASD. Our previous family-based association study also revealed that a specific haplotype of WNT2 (wingless-type MMTV integration site family member 2) gene was overtransmitted to probands with ASD. Whether the CNS patterning genes moderate the clinical phenotype of ASD is unclear. This study investigated the genetic associations of WNT2, engrailed 2 (EN2), and forkhead box P2 (FOXP2) with the clinical symptom severity.

METHODS

The sample included 391 patients (males, 88.3%; mean age±standard deviation, 9.5±4.4 years) diagnosed with ASDs. Tag single nucleotide polymorphisms (SNPs) of EN2, WNT2, and FOXP2 were genotyped. The single-locus and multilocus markers were tested for association.

RESULTS

We found that multilocus markers of WNT2 were associated with stereotyped behaviors whereas the markers of FOXP2 tended to be associated with social deficits. Moreover, an SNP of WNT2 showed a trend to be associated with less inattentive symptoms.

CONCLUSION

Our findings that WNT2 and FOXP2 may moderate the clinical phenotypes of ASD provide evidence to support the possible universal effect of WNT2 and FOXP2 on neurodevelopmental symptom dimensions. Such findings warrant further validation in other independent samples.

TRIAL REGISTRATION

Clinical trial registration identifier: NCT00494754.

The Genetic Overlap of Attention-Deficit/Hyperactivity Disorder and Autistic-like Traits: an Investigation of Individual Symptom Scales and Cognitive markers

Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorders (ASDs) frequently co-occur. However, due to previous exclusionary diagnostic criteria, little is known about the underlying causes of this covariation. Twin studies assessing ADHD symptoms and autistic-like traits (ALTs) suggest substantial genetic overlap, but have largely failed to take into account the genetic heterogeneity of symptom subscales. This study aimed to clarify the phenotypic and genetic relations between ADHD and ASD by distinguishing between symptom subscales that characterise the two disorders. Moreover, we aimed to investigate whether ADHD-related cognitive impairments show a relationship with ALT symptom subscales; and whether potential shared cognitive impairments underlie the genetic risk shared between the ADHD and ALT symptoms. Multivariate structural equation modelling was conducted on a population-based sample of 1312 twins aged 7–10. Social-communication ALTs correlated moderately with both ADHD symptom domains (phenotypic correlations around 0.30) and showed substantial genetic overlap with both inattention and hyperactivity-impulsivity (genetic correlation = 0.52 and 0.44, respectively). In addition to previously reported associations with ADHD traits, reaction time variability (RTV) showed significant phenotypic (0.18) and genetic (0.32) association with social-communication ALTs. RTV captured a significant proportion (24 %) of the genetic influences shared between inattention and social-communication ALTs. Our findings suggest that social-communication ALTs underlie the previously observed phenotypic and genetic covariation between ALTs and ADHD symptoms. RTV is not specific to ADHD symptoms, but is also associated with social-communication ALTs and can, in part, contribute to an explanation of the co-occurrence of ASD and ADHD.

Current viewpoints on DSM-5 in Japan

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) was published in 2013, and its official Japanese version was published in 2014. The Japanese Government uses classifications from the 10th revision of the I nternational C lassification of D iseases (ICD-10) to categorize disorders and determine treatment fees. However, since the publication of the DSM-III, the use of the DSM system has become prevalent in research and educational settings in Japan. In addition to traditional psychiatry, both the ICD and the DSM are taught by many Japanese medical schools, and virtually all clinical research and trials refer to the DSM to define targeted disorders. Amid the current backdrop in which the reputation of the DSM-5 is being established, the editorial board of P sychiatry and C linical N eurosciences has asked Japanese experts across 12 specialties to examine the structure of the DSM-5, including the following categories: Neurodevelopmental Disorders, Schizophrenia Spectrum Disorders, Major Depression, Bipolar Disorders, Obsessive-Compulsive Disorders, Somatic Symptom Disorder, Eating Disorders, Substance-Related and Addictive Disorders, Gender Dysphoria, and Neurocognitive Disorders. Although opinions were only obtained from these selected experts, we believe that we have succeeded, to a certain extent, in presenting views that are representative of each specialty.

Aetiological influences on stability and change in emotional and behavioural problems across development: a systematic review

Emotional and behavioural problems in childhood and adolescence can be chronic and are predictive of future psychiatric problems. Understanding what factors drive the development and maintenance of these problems is therefore crucial. Longitudinal behavioural genetic studies using twin, sibling or adoption data can be used to explore the developmental aetiology of stability and change in childhood and adolescent psychopathology. We present a systematic review of longitudinal, behavioural genetic analyses of emotional and behavioural problems between ages 0 to 18 years. We identified 58 studies, of which 19 examined emotional problems, 30 examined behavioural problems, and 9 examined both. In the majority of studies, stability in emotional and behavioural problems was primarily genetically influenced. Stable environmental factors were also widely found, although these typically played a smaller role. Both genetic and environmental factors were involved in change across development. We discuss the findings in the context of the wider developmental literature and make recommendations for future research.

Meta-analysis of social cognition in attention-deficit/hyperactivity disorder (ADHD): comparison with healthy controls and autistic spectrum disorder

BACKGROUND

Impairment in social cognition is an established finding in autism spectrum disorders (ASD). Emerging evidence suggests that attention-deficit/hyperactivity disorder (ADHD) might be also associated with deficits in theory of mind (ToM) and emotion recognition. However, there are inconsistent findings, and it has been debatable whether such deficits persist beyond childhood and how similar social cognitive deficits are in ADHD v. ASD.

METHOD

We conducted a meta-analysis of social cognition, including emotion recognition and ToM, studies in ADHD compared with healthy controls and ASD. The current meta-analysis involved 44 studies comparing ADHD (n = 1999) with healthy controls (n = 1725) and 17 studies comparing ADHD (n = 772) with ASD (n = 710).

RESULTS

Facial and vocal emotion recognition (d = 0.40-0.44) and ToM (d = 0.43) abilities were significantly impaired in ADHD. The most robust facial emotion recognition deficits were evident in anger and fear. Social cognitive deficits were either very subtle (emotion recognition) or non-significant (ToM) in adults with ADHD. Deficits in social cognition, especially ToM, were significantly more pronounced in ASD compared with ADHD. General cognitive impairment has contributed to social cognitive deficits in ADHD.

CONCLUSIONS

Performance of individuals with ADHD on social cognition lies intermediate between ASD and healthy controls. However, developmental trajectories of social cognition probably differ between ADHD and ASD as social cognitive deficits in ADHD might be improving with age in most individuals. There is a need for studies investigating a potential subtype of ADHD with persistent social cognitive deficits and exploring longitudinal changes in social cognition during development.

Autism Spectrum Disorders and Other Mental Health Problems: Exploring Etiological Overlaps and Phenotypic Causal Associations

OBJECTIVE

Recent studies have highlighted the impact of coexisting mental health problems in autism spectrum disorders (ASD). No twin studies to date have reported on individuals meeting diagnostic criteria of ASD. This twin study reports on the etiological overlap between the diagnosis of ASD and emotional symptoms, hyperactivity, and conduct problems measured with the Strengths and Difficulties Questionnaire.

METHOD

Genetic and environmental influences on the covariance between ASD and coexisting problems were estimated, in line with the correlated risks model prediction. Phenotypic causality models were also fitted to explore alternative explanations of comorbidity: namely, that coexisting problems are the result of or result in ASD symptoms; that they increase recognition of ASD; or that they arise due to an over-observation bias/confusion when differentiating between phenotypes.

RESULTS

More than 50% of twins with broad spectrum/ASD met the borderline/abnormal levels cut-off criteria for emotional symptoms or hyperactivity, and approximately 25% met these criteria for the 3 reported problems. In comparison, between 13% and 16% of unaffected twins scored above the cut-offs. The phenotypic correlation between ASD and emotional symptoms was explained entirely by genetic influences and accompanied by a moderate genetic correlation (0.42). The opposite was true for the overlap with conduct problems, as nonshared-environmental factors had the strongest impact. For hyperactivity, the best-fitting model suggested a unidirectional phenotypic influence of hyperactivity on ASD.

CONCLUSION

Our findings suggest a possible effect of hyperactivity on identification of ASD. The lack of genetic influences on conduct problems-ASD overlap further supports the genetic independence of these 2 phenotypes. Finally, the co-occurrence of emotional symptoms in ASD, compared to other co-occurring problems, is completely explained by common genetic effects.

Identifying the lost generation of adults with autism spectrum conditions

Autism spectrum conditions comprise a set of early-onset neurodevelopmental syndromes with a prevalence of 1% across all ages. First diagnosis in adulthood has finally become recognised as an important clinical issue due to the increasing awareness of autism, broadening of diagnostic criteria, and the introduction of the spectrum concept. Thus, the idea of a lost generation of people who were previously excluded from a diagnosis of classic autism has arisen. Making a first diagnosis of autism spectrum conditions in adults can be challenging for practical reasons (eg, no person to provide a developmental history), developmental reasons (eg, the acquisition of learnt or camouflaging strategies), and clinical reasons (eg, high frequency of co-occurring disorders). The diagnostic process includes referral, screening, interviews with informants and patients, and functional assessments. In delineating differential diagnoses, true comorbidities, and overlapping behaviour with other psychiatric diagnoses, particular attention should be paid to anxiety, depression, obsessive-compulsive disorder, psychosis, personality disorders, and other neurodevelopmental disorders. Possible misdiagnosis, especially in women, should be explored. The creation of supportive, accepting, and autism-friendly social and physical environments is important and requires a coordinated effort across agencies and needs support from government policies.

A longitudinal twin study of the association between childhood autistic traits and psychotic experiences in adolescence

Background

This twin study investigated whether autistic traits during childhood were associated with adolescent psychotic experiences.

Methods

Data were collected from a community sample of approximately 5000 twin pairs, which included 32 individuals with diagnosed autism spectrum conditions (ASC). Parents rated autistic traits in the twins at four points between ages 8–16 years. Positive, negative, and cognitive psychotic experiences were assessed at age 16 years using self- and parent-report scales. Longitudinal twin analyses tested the associations between these measures.

Results

Autistic traits correlated weakly or nonsignificantly with positive psychotic experiences (paranoia, hallucinations, and grandiosity), and modestly with cognitive psychotic experiences (cognitive disorganisation). Higher correlations were observed for parent-rated negative symptoms and self-reported anhedonia, although the proportion of variance in both accounted for by autistic traits was low (10 and 31 %, respectively). The majority of the genetic influences on negative symptoms and anhedonia were independent of autistic traits. Additionally, individuals with ASC displayed significantly more negative symptoms, anhedonia, and cognitive disorganisation than controls.

Conclusions

Autistic traits do not appear to be strongly associated with psychotic experiences in adolescence; associations were also largely restricted to negative symptoms. Of note, the degree to which the genetic and environmental causes of autistic traits influenced psychotic experiences was limited. These findings thus support a phenotypic and etiological distinction between autistic traits and psychotic experiences.

Electronic supplementary material

The online version of this article (doi:10.1186/s13229-015-0037-9) contains supplementary material, which is available to authorized users.

Using Sibling Designs to Understand Neurodevelopmental Disorders: From Genes and Environments to Prevention Programming

Neurodevelopmental disorders represent a broad class of childhood neurological conditions that have a significant bearing on the wellbeing of children, families, and communities. In this review, we draw on evidence from two common and widely studied neurodevelopmental disorders-autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD)-to demonstrate the utility of genetically informed sibling designs in uncovering the nature and pathogenesis of these conditions. Specifically, we examine how twin, recurrence risk, and infant prospective tracking studies have contributed to our understanding of genetic and environmental liabilities towards neurodevelopmental morbidity through their impact on neurocognitive processes and structural/functional neuroanatomy. It is suggested that the siblings of children with ASD and ADHD are at risk not only of clinically elevated problems in these areas, but also of subthreshold symptoms and/or subtle impairments in various neurocognitive skills and other domains of psychosocial health. Finally, we close with a discussion on the practical relevance of sibling designs and how these might be used in the service of early screening, prevention, and intervention efforts that aim to alleviate the negative downstream consequences associated with disorders of neurodevelopment.

Where are the strongest associations between autistic traits and traits of ADHD? evidence from a community-based twin study

Autism spectrum conditions (ASC) and attention-deficit/hyperactivity disorder (ADHD) regularly co-occur. Twin studies increasingly indicate that these conditions may have overlapping genetic causes. Less is known about the degree to which specific autistic traits relate to specific behaviours characteristic of ADHD. We hence tested, using the classical twin design, whether specific dimensional autistic traits, including social difficulties, communication atypicalities and repetitive behaviours, would display differential degrees of aetiological overlap with specific traits of ADHD, including hyperactivity/impulsivity and inattention. Parents of approximately 4,000 pairs of 12-year-old twins completed the Childhood Autism Spectrum Test and Conners' Parent Rating Scale. These measures were divided into subscales corresponding to different types of autistic and ADHD behaviours. Twin model fitting suggested that the degree of genetic overlap was particularly strong between communication difficulties and traits of ADHD (genetic correlations = .47-.51), while repetitive behaviours and social difficulties showed moderate (genetic correlations = .12-.33) and modest (.05-.11) genetic overlap respectively. Environmental overlap was low across all subscales (correlations = .01-.23). These patterns were also apparent at the extremes of the general population, with communication difficulties showing the highest genetic overlap with traits of ADHD. These findings indicate that molecular genetic studies seeking to uncover the shared genetic basis of ASC and ADHD would benefit from taking a symptom-specific approach. Furthermore, they could also help to explain why studies of the communication abilities of individuals with ASC and ADHD have produced overlapping findings.

Can autism spectrum disorders and social anxiety disorders be differentiated by the social responsiveness scale in children and adolescents?

Autism spectrum disorder (ASD) as well as social phobia (SP), and selective mutism (SM) are characterised by impaired social interaction. We assessed the validity of the Social Responsiveness Scale (SRS) to differentiate between ASD, and SP/SM. Raw scores were compared in 6-18 year old individuals with ASD (N = 60), SP (N = 38), SM (N = 43), and typically developed (N = 42). Sensitivity and specificity were examined. The three disorders showed overlapping SRS scores. Especially in boys with SM (ROC-AUC = .81), presence of ASD was overestimated by the SRS. A combination of three disorder specific questionnaires resulted in marginally improved diagnostic accuracy. For the clinically very relevant differential diagnosis of SP/SM, SRS results must be interpreted with caution.

Factor structure of autistic traits in children with ADHD

Attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) often co-occur. Factor analyses of ASD traits in children with and without ASD indicate the presence of social and restrictive–repetitive behaviour (RRB) factors. This study used exploratory factor analyses to determine the structure of ASD traits (assessed using the Social Communication Questionnaire) in children with ADHD. Distinct factors were observed for ‘social’ and ‘rigidity’ traits, corresponding to previous factor analyses in clinical ASD and population samples. This indicates that the split between social-communicative and RRB dimensions is unaffected by ADHD in children. Moreover, the study also finds that there is some overlap across hyperactive-impulsive symptoms and RRB traits in children with ADHD, which merits further investigation.

Genetic risk for attention-deficit/hyperactivity disorder contributes to neurodevelopmental traits in the general population

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) can be viewed as the extreme end of traits in the general population. Epidemiological and twin studies suggest that ADHD frequently co-occurs with and shares genetic susceptibility with autism spectrum disorder (ASD) and ASD-related traits. The aims of this study were to determine whether a composite of common molecular genetic variants, previously found to be associated with clinically diagnosed ADHD, predicts ADHD and ASD-related traits in the general population.

METHODS

Polygenic risk scores were calculated in the Avon Longitudinal Study of Parents and Children (ALSPAC) population sample (N = 8229) based on a discovery case-control genome-wide association study of childhood ADHD. Regression analyses were used to assess whether polygenic scores predicted ADHD traits and ASD-related measures (pragmatic language abilities and social cognition) in the ALSPAC sample. Polygenic scores were also compared in boys and girls endorsing any (rating ≥ 1) ADHD item (n = 3623).

RESULTS

Polygenic risk for ADHD showed a positive association with ADHD traits (hyperactive-impulsive, p = .0039; inattentive, p = .037). Polygenic risk for ADHD was also negatively associated with pragmatic language abilities (p = .037) but not with social cognition (p = .43). In children with a rating ≥ 1 for ADHD traits, girls had a higher polygenic score than boys (p = .003).

CONCLUSIONS

These findings provide molecular genetic evidence that risk alleles for the categorical disorder of ADHD influence hyperactive-impulsive and attentional traits in the general population. The results further suggest that common genetic variation that contributes to ADHD diagnosis may also influence ASD-related traits, which at their extreme are a characteristic feature of ASD.

The Roots of Autism and ADHD Twin Study in Sweden (RATSS)

Neurodevelopmental disorders affect a substantial minority of the general population. Their origins are still largely unknown, but a complex interplay of genetic and environmental factors causing disturbances of the central nervous system's maturation and a variety of higher cognitive skills is presumed. Only limited research of rather small sample size and narrow scope has been conducted in neurodevelopmental disorders using a twin-differences design. The Roots of Autism and ADHD Twin Study in Sweden (RATSS) is an ongoing project targeting monozygotic twins discordant for categorical or dimensional autistic and inattentive/hyperactive-impulsive phenotypes as well as other neurodevelopmental disorders, and typically developing twin controls. Included pairs are 9 years of age or older, and comprehensively assessed for psychopathology, medical history, neuropsychology, and dysmorphology, as well as structural, functional, and molecular brain imaging. Specimens are collected for induced pluripotent (iPS) and neuroepithelial stem cells, genetic, gut bacteria, protein-/monoamine, and electron microscopy analyses. RATSS's objective is to generate a launch pad for novel surveys to understand the complexity of genotype-environment-phenotype interactions in autism spectrum disorder and attention-deficit hyperactivity disorder (ADHD). By October 2013, RATSS had collected data from 55 twin pairs, among them 10 monozygotic pairs discordant for autism spectrum disorder, seven for ADHD, and four for other neurodevelopmental disorders. This article describes the design, recruitment, data collection, measures, collected pairs' characteristics, as well as ongoing and planned analyses in RATSS. Potential gains of the study comprise the identification of environmentally mediated biomarkers, the emergence of candidates for drug development, translational modeling, and new leads for prevention of incapacitating outcomes.

Autistic traits in children with ADHD index clinical and cognitive problems

Traits of autistic spectrum disorders (ASD) occur frequently in attention deficit hyperactivity disorder (ADHD), but the significance of their presence in terms of phenotype and underlying neurobiology is not properly understood. This analysis aimed to determine whether higher levels of autistic traits, as measured by the Social Communication Questionnaire (SCQ), index a more severe presentation in a large, rigorously phenotyped sample of children with ADHD (N=711). Regression analyses were used to examine association of SCQ scores with core ADHD features, clinical comorbidities and cognitive and developmental features, with adjustment for putative confounders. For outcomes showing association with total SCQ score, secondary analyses determined levels of differential association of the three ASD sub-domains. Results suggest that increasing ASD symptomatology within ADHD is associated with a more severe phenotype in terms of oppositional, conduct and anxiety symptoms, lower full-scale IQ, working memory deficits and general motor problems. These associations persisted after accounting for ADHD severity, suggesting that autistic symptomatology independently indexes the severity of comorbid impairments in the context of ADHD. Sub-domain scores did not show unique contributions to most outcomes, except that social deficits were independently associated with oppositional symptoms and repetitive behaviours independently predicted hyperactive-impulsive symptoms and motor problems. It would be worthwhile for clinicians to consider levels of socio-communicative and repetitive traits in those with ADHD who do not meet diagnostic criteria for ASD, as they index higher levels of phenotypic complexity, which may have implications for efficacy of interventions.