Autistic Traits In a ADHD Clinical Sample Vs. Control Group

Background:  

Autism traits in ADHD have received recent attention. Few studies have examined autistic symptoms in ADHD clinical samples finding prevalence rates between 65 to 80%. Since autism traits are normally distributed in general population, it is important to study autism traits in ADHD vs. general population samples

Objectives:  

To examine social reciprocity problems in a clinical ADHD sample and a control group without ADHD.

Methods:  

The sample consisted of 60 children who seek psychiatric treatment in the outpatient ADHD clinic of Hospital Psiquiatrico Infantil Dr. Juan N. Navarro and 40 children from the general population. Parents completed a semi-structured DSM-IV oriented interview by a senior board certified child psychiatrist to assign a “pure” ADHD diagnosis (without ASD) Measures: The Social Reciprocity Scale (SRS) was completed by the parents.

Results:  

Overall the age range of the whole sample (N=100) was between 3 to 17 years old with a mean age of 9.19 (SD 3.32), 68.6% were males. The Control group (Co) had a higher SES (15.7vs.8.6) compared to the ADHD group (p<.0001), and the proportion of males was higher in the ADHD vs. control group (86.7% vs. 42.5% p <.0001). The ADHD DSM-IV subtype composition was Combined type (C) (63.3%)  Inattentive (I) (23.3%) and Hyperactive-impulsive type (H/I) (13.3%). The SRS mean total score for the ADHD group was 86.67± 26.99 vs. 47.58 ± 7.6 for the Control group t(98)=8.90, p<0.0001. In the ADHD sample a SRS cutoff ≥ 85 identify 45% children with autistic traits, in contrast no children from the control group met the cutoff ≥85 or 65 (suggested in some studies for community samples). By ADHD subtypes the prevalence for autistic traits was higher for the combined type (81.5%) followed by the inattentive (14.8%) and the Hyperactive-impulsive type (3.7%) had the lowest prevalence. Analysis of variance (ANOVA) indicated significant mean differences in mean SRS scores among ADHD subtypes:  C>I>H/I/>Co (F(3,99) = 34.75, p<0.0001). Dunnet C post hoc analyses revealed that compared to the Control group children in the Combined and the Inattentive ADHD subtypes groups had higher autistic traits measured by SRS (mean difference of 46.50, and 29.06 respectively vs. control group p=.05)

Conclusions:  

Compared to children from the general population patients with ADHD have more autistic traits, the prevalence (48%) is even higher than ADHD samples from the general population reported in previous studies.