Evidence for overlapping genetic influences on autistic and ADHD behaviors in a community twin sample

Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, London, UK.
Journal of Child Psychology and Psychiatry (Impact Factor: 6.46). 06/2008; 49(5):535-42. DOI: 10.1111/j.1469-7610.2007.01857.x
Source: PubMed


High levels of clinical comorbidity have been reported between autistic spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD). This study takes an individual differences approach to determine the degree of phenotypic and aetiological overlap between autistic traits and ADHD behaviours in the general population.
The Twins Early Development Study is a community sample born in England and Wales. Families with twins born in 1994-6 were invited to join; 6,771 families participated in the study when the twins were 8 years old. Parents completed the Childhood Asperger Syndrome Test and the Conners' DSM-IV subscales. Teacher data were also collected on a sub-sample. High scores on the Conners' subscales were used to identify possible ADHD cases. Potential ASD cases were interviewed using the Development and Well-Being Assessment. Multivariate structural equation model-fitting was employed, as well as DeFries Fulker extremes analysis and liability threshold model-fitting.
Significant correlations were found between autistic and ADHD traits in the general population (.54 for parent data, .51 for teacher data). In the bivariate models, all genetic correlations were >.50, indicating a moderate degree of overlap in genetic influences on autistic and ADHD traits, both throughout the general population and at the quantitative extreme. This phenotypic and genetic overlap still held when sex, IQ and conduct problems were controlled for, for both parent and teacher data. There was also substantial overlap in suspected cases (41% of children who met criteria for an ASD had suspected ADHD; 22% with suspected ADHD met criteria for an ASD).
These results suggest there are some common genetic influences operating across autistic traits and ADHD behaviours throughout normal variation and at the extreme. This is relevant for molecular genetic research, as well as for psychiatrists and psychologists, who may have assumed these two sets of behaviours are independent.

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    • "). Analysis of ratings on a UK population-based twin sample (Twins' Early Development Study; TEDS) at age 8 yielded significant phenotypic correlations (rPH around 0.50) between ADHD symptoms and ALTs (Ronald et al. 2008). Substantial common genetic influences (genetic correlations; rG>0.50) were found whether assessing co-variation throughout the population , at the quantitative extreme, or adopting a categorical approach (Ronald et al. 2008). These findings were consistent across genders and informants. "
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    ABSTRACT: 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.
    Journal of Abnormal Child Psychology 05/2015; DOI:10.1007/s10802-015-0037-4 · 3.09 Impact Factor
    • "by shared genetic influences (Rommelse et al. 2009; Ronald et al. 2008). A large body of research has investigated shared and distinct cognitive features of ASD, ADHD and ASD ? "
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    ABSTRACT: Autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) often co-occur. Children with ASD and ADHD demonstrate deficits in adaptive functioning, yet pure and comorbid groups have not been directly compared. Vineland Adaptive Behaviour Scales (VABS-II) data were examined in boys with ASD (n = 17), ADHD (n = 31) and ASD + ADHD (n = 38). Results demonstrated lower socialisation and composite scores and greater discrepancy between cognitive and adaptive abilities in the ASD + ADHD group compared to the ADHD-only group. Significant associations were shown between reduced adaptive functioning and autism symptoms, but not ADHD symptoms. Children with ASD + ADHD present with exacerbated impairments in adaptive functioning relative to children with ADHD, associated with ASD symptoms. Disentangling variation in adaptive skills may aid the assessment of complex cases.
    Journal of Autism and Developmental Disorders 01/2015; 45(7). DOI:10.1007/s10803-014-2352-y · 3.34 Impact Factor
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    • "More than 50% of patients with ASD meet the criteria of ADHD, and have higher scores for hyperactivity-impulsivity symptoms (Lee & Ousley, 2006). Several recent large scale genome-wide studies have suggested that ASD and ADHD may share the same genetic susceptibility, which may explain this frequent comorbid phenomenon between ASD and ADHD (Ronald, Simonoff et al., 2008; Nijmeijer, Arias-Vasquez et al., 2010; Goldin, Matson et al., 2013). "
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    ABSTRACT: Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are both frequently comorbid with other psychiatric disorders, but the comorbid effect of ASD and ADHD relative to the comorbid risk of other psychiatric disorders is still unknown. Using the Taiwan National Health Insurance Research Database, 725 patients with ASD-alone, 5694 with ADHD-alone, 466 with ASD + ADHD, and 27,540 (1:4) age-/gender-matched controls were enrolled in our study. The risk of psychiatric comorbidities was investigated. The ADHD + ASD group had the greatest risk of developing schizophrenia (hazard ratio [HR]: 95.89; HR: 13.73; HR: 174.61), bipolar disorder (HR: 74.93; HR: 19.42; HR: 36.71), depressive disorder (HR: 17.66; HR: 12.29; HR: 9.05), anxiety disorder (HR: 49.49; HR: 50.92; HR: 14.12), disruptive behavior disorder (HR: 113.89; HR: 93.87; HR: 26.50), and tic disorder (HR: 8.95; HR: 7.46; HR: 4.87) compared to the ADHD-alone, ASD-alone, and control groups. Patients with ADHD + ASD were associated with the greatest risk of having comorbid bipolar disorder, depressive disorder, anxiety disorder, disruptive behavior disorder, and tic disorder. The diagnoses of ASD and ADHD preceded the diagnoses of other psychiatric comorbidities. A comprehensive interview scrutinizing the psychiatric comorbidities would be suggested when encountering and following patients with both ASD and ADHD in clinical practice.
    Research in Autism Spectrum Disorders 11/2014; 10. DOI:10.1016/j.rasd.2014.10.014 · 2.96 Impact Factor
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