Screening for Autism Spectrum Disorders in Epilepsy and Tuberous Sclerosis Complex with the SRS and SCQ

Background: Screening for autism spectrum disorders (ASDs) is of considerable utility in settings where children and adolescents with epilepsy are evaluated. For example, epilepsy occurs in approximately 5-38 percent of individuals with ASDs and in tuberous sclerosis complex (TSC), a disorder typically associated with epilepsy, ASD occurs in approximately 25-50 percent of cases. Rapid detection of ASDs will lead to earlier treatment and improved outcomes. The Social Responsiveness Scale (SRS) and the Social Communication Questionnaire (SCQ) are two commonly administered instruments used to screen for ASDs.

Objectives: The present analysis investigates the utility of the SRS and SCQ in detecting ASDs in children with TSC and epilepsy versus children with epilepsy only.

Methods: 21 patients with TSC (12 males and nine females, ages 5-18, mean = 10.10, SD = 4.30) and 50 patients with epilepsy (26 males and 24 females, ages 4-17, mean = 10.32, SD = 4.27) were assessed. Parents completed SRS and SCQ forms. An independent samples t-test compared mean scores on the SRS and SCQ of the patients with TSC and patients with epilepsy. Chi-square analyses assessed the classification rates of ASD for the SRS and SCQ scores across the patient populations.

Results: The mean SRS total T-score for patients with epilepsy was 63.44, SD = 13.61 (range = 41-92) and the mean SRS total T-score for patients with TSC was 69.67, SD = 17.39 (range = 42-98). There was no significant mean score difference between these patient populations on this measure (t = 1.618, p = .110) means of these two patient populations.
30% of patients with epilepsy had SRS total T-scores that were above the cutoff for ASD, whereas 52.3% of patients with TSC had SRS total T-scores that were above the cutoff. The chi-square test did not reveal any significant differences in the frequency at which epilepsy and TSC patients were classified as ASD.
The mean SCQ total for patients with epilepsy was was 8.24, SD = 5.71 (range = 0-25) and the mean SCQ total for patients with TSC was 13.10, SD = 7.54 (range = 2-28). Scores were significantly greater for TSC patients (t = 2.967, p <.005).
10% of patients with epilepsy had SCQ total scores above the cutoff for ASDs, whereas 42.8% of patients with TSC had SCQ total scores that were above the cutoff. Pearson’s chi-square was significant (8.450, p<.005).

Conclusions: Only scores on the SCQ significantly differed between epilepsy and TSC groups. The SRS may be overestimating autism in this sample of children with epilepsy not due to TSC.