Abstract
BACKGROUND: Approximately 30% of autism spectrum disorder (ASD) cases exhibit developmental regression after a period of typical development, leading to what is known as regressive autism. Our understanding of the factors underlying regression, including precise mechanisms, clinical features, and risk factors, remains limited. This study aims to compare children with ASD with language regression (ASD-LR) to those without developmental regression (ASD-NR) in terms of clinical and demographic characteristics and to identify potential predictors. METHODS: In this cross-sectional retrospective study, children aged 2-6 diagnosed with ASD-LR were matched for age and gender with children diagnosed with ASD-NR between January 2023 and January 2024. The groups were compared in terms of demographic and clinical characteristics. RESULTS: The mean age of the ASD-LR group (n = 32) was 52.16 ± 14.56 months, and the ASD-NR group (n = 50) had a mean age of 48.76 ± 13.41 months. Univariate analyses revealed no significant differences in autism severity between groups in clinician (P = .367) and parent evaluations (P = .541). However, in the ASD-LR group, a significant relationship was found between regression, a history of febrile seizures (P = .012), a father's psychiatric background (P = .002), and a family history of psychiatric disorders (P < .001). Family history of psychiatric disorders (OR 7.54, 95% CI 1.10-51.64, P = .040) and cesarean delivery (odds ratio 3.90, 95% CI 1.05-14.47, P = .042) were identified as independent predictors of language regression. CONCLUSION: The results indicate that regression may be associated with both genetic and environmental factors, including a family history of psychiatric disorders, cesarean delivery, and febrile seizure. Future research should focus on explaining these factors and identifying potential preventive measures.