Autism Speaks, Science, Latest Research

E. Saemundsen
Division of Autism Spectrum Disorders, State Diagnostic and Counseling Center, Digranesvegur 5, 200 Kópavogur, Iceland

P. Ludvigsson, Dept. of Pediatrics, Landspitali, University Hospital, vid Hringbraut, 101 Reykjavik, Iceland

V. Rafnsson, Dept. of Preventive Medicine and Epidemiology, University of Iceland, 101 Reykjavik, Iceland

Abstract
Background: A subgroup of children diagnosed with autism spectrum disorder (ASD) has a history of unprovoked seizures in the first year of life.

Objectives: To study the association between unprovoked seizures in the first year of life and ASD.

Methods: Children diagnosed with seizures in the first year of life during the period 1982-1998 were identified in hospital records of all the pediatric in-patient facilities in Iceland. Of 121 children five had died and one lived abroad. The parents of 115 children were invited into a study of possible ASD. The Social Communication Questionnaire was used as an initial test of autistic behaviors, followed by the ADI-R and the ADOS and/or the CARS. Prevalence of ASD as the percentage of cases and exact 95% confidence intervals (CI) were calculated. Logistic regression was used to calculate odds ratio (OR) and 95% CI.

Results: Ninety-five children participated (82.6%). Of these, 17 (17.9%) had infantile spasms (IS) and 78 (81.1%) had other types of seizures. Thirteen children or 13.7% (95% CI, 7.5-22.3) had ASD, eight females and five males. Six of the children with ASD had IS, and seven had other types of epilepsy. All but one had intellectual disability (ID), and six had profound ID (IQ<20). The OR was 1.55 (95% CI, 0.33-7.37) for children with IS compared to those without IS, adjusted for symptomatic origin of seizures. The OR was 8.73 (95% CI, 1.88-40.54) for children with symptomatic origin of seizures compared to those with non-symptomatic seizures, adjusted for IS.

Conclusions: High prevalence of ASD was found in children with a history of unprovoked seizures in the first year of life. There was an overrepresentation of the female gender and ID in the ASD group. The symptomatic origin of seizures increased the risk of ASD, rather than IS.

Lay Abstract
Historically, epilepsy was one of the first biological factors to be associated with autism. It has been known for some time that children with autism spectrum disorder (ASD) have a high rate of epilepsy. An association between ASD and a particular epilepsy syndrome in infancy, infantile spasms, has been suggested. Whether other unprovoked seizures in the first year of life present a risk of ASD is unknown. The objective of the present study was to see if unprovoked seizures in the first year of life were associated with a risk for ASD.

Children diagnosed with seizures in the first year of life during the period 1982-1998 were identified in hospital records of all pediatric in-patient facilities in Iceland. Of the 121 children identified, five had died and one lived abroad. The parents of the remaining 115 children were invited into a study of possible ASD. Seizures were classified as either symptomatic or non-symptomatic (cryptogenic) and a questionnaire was used as an initial test of autistic behaviors, followed by diagnostic instruments.

Ninety-five children participated (82.6%) and of those, 17 (17.9%) had infantile spasms and 78 (81.1%) had other types of seizures. Thirteen children or 13.7% had ASD, eight females and five males. Six of the children with ASD had infantile spasms, and seven had other types of epilepsy. All but one had intellectual disability, and six had profound intellectual disability (IQ<20). Children with unprovoked seizures in the first year of life had increased risk of developing ASD. Overall, those with infantile spasms were 1.55 times more likely to develop ASD than children with other seizure types. However, children with seizures of symptomatic origin, irrespective of type, were nearly 9 times more likely to develop ASD than those with non-symptomatic seizures.

In conclusion, high prevalence of ASD was found in children with a history of unprovoked seizures in the first year of life. There was a high prevalence of females and individuals with intellectual disability in the ASD group. Seizures of symptomatic origin in the first year of life were a strong predictor of ASD regardless of seizure type.