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The etiology of autism: pre-, peri- and neonatal factors
1Department of Psychiatry, Johns Hopkins University, School of Medicine, Baltimore, MD.
Insights
Autism risk factors are not linked to overall optimality scores when birth order is considered. Previous findings of an association were likely due to not adjusting for birth order in autism research.
Area of Science:
- Neurodevelopmental disorders
- Autism Spectrum Disorder (ASD) research
- Pediatric health
Background:
- Previous studies suggested a link between pre-, peri-, and neonatal optimality and autism.
- Composite optimality scores were used to assess developmental factors.
Purpose of the Study:
- To re-examine pre-, peri-, and neonatal factors in autism using composite optimality scores.
- To determine if birth order influences the association between optimality and autism.
Main Methods:
- Utilized a modified Gillberg Optimality Scale (Modified-GOS) on 39 autistic subjects and 39 sibling controls.
- Scores were derived from best-estimate ratings of maternal interviews and medical records.
- Established rules for best-estimate ratings based on inter-source agreement.
Main Results:
- No significant differences in overall optimality were found between autistic subjects and controls after adjusting for maternal parity (birth order).
- Maternal parity was the only significant variable, with an excess of first and fourth-born children among autistic subjects.
Conclusions:
- The apparent association between optimality and autism in prior research may be an artifact of not accounting for birth order.
- Birth order is a critical factor to consider in autism etiology studies.
Objective:
To examine pre-, peri-, and neonatal factors in autism using composite optimality scores.
Method:
Pre-, peri-, and neonatal composite optimality scores were examined in 39 autistic subjects and 39 randomly matched sibling controls using a modification of the Gillberg Optimality Scale (Modified-GOS). Scores were based on best-estimate ratings of maternal interviews and medical records. Rules for best-estimate ratings were derived from a study of agreement between these two sources.
Results:
Significant differences in optimality between autistic probands and their siblings were not present after adjustment for "maternal parity." Examination of specific variables revealed that only maternal parity differed significantly between autistic subjects and randomly matched sibling controls, reflecting an excess of first and fourth born among the autistic subjects.
Conclusion:
The findings of this study suggest that previous reports of an association between optimality and autism are a result of failure to adjust for birth order.