Factors Associated with Irritability in Children with Autism Spectrum Disorder Compared to Children with Other Developmental Disabilities

Background:  It has been reported that children with Autism Spectrum Disorders (ASD) are more irritable than children with other developmental disabilities (DD).  There are conflicting reports about associations between irritability and specific factors such as gastrointestinal and sleeping problems.  However, it is possible that irritability in children with ASD is more related to these factors than for children with other DDs.

Objectives:  To compare reported irritability in ethnically diverse children with ASD vs. those with other DDs and to assess the relationship of irritability to feeding/gastrointestinal (GI) and sleep problems.

Methods:  Cross sectional study with structured interview for 50 children with ASD and 50 children with other DD, matched by age/gender. DDs included intellectual disability/global delay and cerebral palsy.  Interview included: Aberrant Behavior Checklist (ABC), GI Questionnaire and Child's Sleep Habits Questionnaire. Irritability was defined as scores above the 85^th %ile on the ABC. Statistical analysis included chi-square, t test, correlations and regression.

Results:  Mean age 8 3 yr; 15% White, 44% Hispanic and 24% African/American. Irritability was reported in 53% of the ASD group and 20% of the DD group (p<0.001). Children with ASD presented more co-morbid symptoms: GI (66% vs. 40%, p=0.04) and sleep problems (78% vs. 33%, p<0.001). In the ASD group irritability was related to food selectivity with textures (58% vs. 13%, p=0.002) and GI symptoms (88% vs. 59%, p=0.04), especially diarrhea (65% vs. 35%, p=0.04); there was no association with sleep problems (81% vs. 74%, p=0.7) or food allergies (12% vs. 17% p=0.6). In the DD group, irritability was associated only with sleep problems (70% vs. 25%, p=0.02); there was no association with feeding/GI symptoms or food allergies. There were no associations between demographic characteristics and reported irritability for either group.  The association between irritability and ASD persisted after adjusting for demographic characteristics (including maternal education), sleep and GI problems. (OR 5.3 95%, CI 1.8-15.5).

Conclusions:  In this ethnically diverse sample, children with ASD were more frequently reported to be irritable than children with other DDs. Factors associated with irritability included GI and food selectivity in the ASD group and sleep problems in the DD group. Interestingly, the association between ASD and irritability was independent of GI or sleep problems.