Editorial

DSM-5's Conceptualization of Autistic Disorders

Social Communication Disorder (SCD) is a new DSM-5 diagnostic category poorly understood by clinicians. We describe a case series of four individuals diagnosed with SCD to identify common characteristics and differences in presentations of the disorder. All cases had deficits in the area of social communication, and sub-threshold level of restricted and repetitive behaviours, not sufficient to meet criteria for Autism Spectrum Disorder (ASD). All cases presented with at least one mental health co-morbid condition. There are significant overlaps in clinical presentation between SCD and ASD. It is imperative that accurate diagnostic tools and effective intervention approaches of SCD be developed.

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.

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).

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).

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.

With a view to developing a brief screening instrument for autism symptoms in a general population of adolescents, seven items from the Asperger syndrome (and high-functioning autism) diagnostic interview were adapted for use as self-report in an online questionnaire for youths aged 16–19 years (N = 10,220). The selected items target lack of social understanding (4 items) and rigid and repetitive behavior and interests (RRBI; 3 items). Factor analyses were performed, and the seven items were also validated against self-reported ASD diagnosis. Best statistical model fit was found for a bifactor model with one general factor and two domain specific factors tied to social difficulties and RRBI. Both the general and the domain specific factors were associated with self-reported ASD diagnoses. The scale (referred to as the Autism Symptom SElf-ReporT for Adolescents and Adults – ASSERT) had good screening properties with a receiver operating curve-area under the curve (ROC-AUC) of 0.87 and a diagnostic odds ratio (DOR) of 15.8. Applying a modified scoring of the scale further improved the screening properties leading to a ROC-AUC of 0.89 and a DOR of 24.9. The ASSERT holds promise as a brief self-report screen for autism symptoms in adolescents, and further studies should explore its usefulness for adults.

Autism is the most severe end of a spectrum of neurodevelopmental conditions, autism spectrum disorders (ASD). ASD are genetically heterogeneous, and hundreds of genes have been implicated in the etiology of the disease. Here, we discuss the contribution of brain transcriptome studies in advancing our understanding of the genetic mechanisms of ASD and review recent work characterizing the spatial and temporal variation of the human brain transcriptome, with a focus on the relevance of these data to autism susceptibility genes.