Psychological Treatment for Obsessive-Compulsive Disorder in People with Autism Spectrum Disorders – A Pilot Study

of whom were clinical psychologists trained in CBT and experienced in adapting therapy for people with ASD. None of the participants in the TAU group (n = 12) received CBT targeted for OCD in the follow-up period. The CBT and TAU groups did not differ with respect to gender, IQ or length of time between symptom measurement, which averaged at 15.9 months (SD = 10.7). The TAU group was significantly older than the CBT group [TAU group mean age = 32.1 (SD = 9.8), CBT group mean age = 23.8 (SD = 4.3), t = 2.6, d.f. = 21, p = 0.017]. Equivalent numbers of both groups (50%) had been inpatients at some time during the study. There were no significant differences between the groups in the proportion of participants with additional psychopathology [ 2 = 0.4, d.f. = 2, p = 0.819; 6 (50%) of the CBT group had additional diagnoses, compared to 5 (41.6%) of the TAU group]. The majority of additional diagnoses were of recurrent uni-polar depression or anxiety disorder. The CBT group was no more likely to be on medication at the start of treatment than the TAU group (67 vs. 50% respectively;  2 = 0.686, d.f. = 1, p = 0.408). All participants who were on medication had been on a stable dose for a minimum of 6 weeks prior to baseline symptom measurement. The medication was changed for 4 of the CBT group and 2 of the TAU group during treatment. The CBT group had significantly more severe OCD at baseline (see table 1 ) as measured by the YBOCS total severity score. A mixed-model ANOVA with 1 between-groups factor (CBT vs. TAU) and 1 within-groups factor (baseline vs. post-treatment symptom ratings) revealed a significant group by time interaction on the YBOCS total severity score (F = 4.341; d.f. = 1.22; p = 0.049; partial  2 = 0.165), suggesting greater improvement in one group versus the other. The effect of time (i.e. occasion of measurement) was also significant (F = 6.91, d.f. = 1, p = 0.015; partial 2 = 0.239), as was the effect of group (F = 5.61; d.f. = 1; p = 0.027; partial  2 = 0.203). Repeated-measures t tests showed significant preto posttreatment decreases on the YBOCS total severity and obsession scores for the CBT group but not the TAU group ( table 1 ). The compulsions sub-scale of the YBOCS dropped (non-significantly) from before to after treatment in the CBT group (p = 0.09) but remained unchanged in the TAU group (p = 0.8). For the total YBOCS score, the standardized effect size (Cohen’s d) was 1.01. If we consider a 1 25% reduction on the total YBOCS to represent a clinically significant improvement [20] , 7 patients in the CBT group (58%) and only 2 patients in the TAU group (16%) showed a clinically meaningful response (  2 = 4.44, d.f. = 1, p = 0.035). In summary, the clinical implications arising from this preliminary study outline that (1) OCD symptoms in ASD do not show any change over time in the absence of treatment; (2) a considerable proportion of individuals with ASD and OCD show sigHigh rates of anxiety and mood disorders, and particularly obsessive-compulsive disorder (OCD), have been reported in children and adults with autism spectrum disorders (ASD) [1–10] . There have been 2 single-case reports of cognitive behavioural therapy (CBT) for OCD in this population [11, 12] but systematic evaluations of psychological treatment for co-morbid OCD in ASD are rare. A recent randomized controlled trial of group CBT for anxiety in children showed that scores on an OCD scale improved more in patients who received CBT than in those who were on a waiting list [13] . Here we report the results of a non-randomized, non-blind controlled trial comparing CBT for OCD with treatment as usual (TAU) in 24 (21 male, 3 female) high-functioning adults with ASD and co-morbid OCD who were referred to our specialist ASD clinic. All had an IQ in the average range (mean WAIS-III [14] verbal IQ = 100.3, SD = 14.1; mean WAIS-III performance IQ = 95.5, SD = 12.3). Diagnosis of ASD and OCD had been made by a consultant psychiatrist with all cases meeting relevant ICD-10 research criteria. ASD diagnosis was supplemented by the Autism Diagnostic Interview [15] in 16 (66.6%) of the cases and the Autism Diagnostic Observation Schedule [16] in 3 (12.5%) of the cases, administered by a specialist nurse with reliability training. Agreement to carry out the study was obtained from the local ethics committee. Participants were provided with information about the study and asked to sign a consent form. The main outcome measure was the Yale-Brown Obsessive Compulsive Scale (YBOCS) severity scale [17] . OCD symptoms were carefully distinguished from the repetitive phenomena typically seen in this population [see 10 for details]. The CBT group (n = 12) attended a mean of 27.5 (SD = 13.39, range = 10–50) treatment sessions. The length of treatment did not affect the outcome. The treatment was not manual or protocol driven. The model of treatment was standard CBT for OCD (comprising exposure and response prevention as described by Foa and Goldstein [18] and cognitive appraisal of OCD-related beliefs according to methods outlined by Salkovskis [19] ). There were 3 treating therapists, all Received: March 17, 2008 Accepted: March 19, 2008 Published online: November 18, 2008