Neurodevelopmental Disorders, Cognitive Function, and Quality of Life in Children with Congenital Hypothyroidism in a Portuguese Population

Objective: Although neonatal screening programs have reduced severe intellectual disability, children with congenital hypothyroidism (CH) are still at risk for neurodevelopmental deficits and a lower quality of life (QoL). The aim of this study was to evaluate cognitive profiles, prevalence of neurodevelopmental disorders, and QoL in children with CH. Methods: A longitudinal study was conducted at the northern reference endocrinology unit for CH in Portugal. Cognitive assessments were performed at four time points using standardized intelligence scales. Diagnoses of attention deficit hyperactivity disorder (ADHD), learning disorders, and intellectual disability were based on Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition-DSM-V criteria. QoL was measured using the Pediatric Quality of Life Inventory-PedsQL™. Results: Forty-six children (mean age 9.1 years, 58.7% female) were included. While overall intelligence quotients (IQ) scores were normal, later treatment was associated with significantly lower performance IQ (r=-0.50, p=0.028) and perceptual organization index (r=-0.57, p=0.022). ADHD was present in 26%, and affected children showed lower verbal IQ (90.2 vs. 106.8, p=0.022), perceptual organization index (79.9 vs. 95.2, p=0.041), and school-related QoL (63.3 vs. 81.6, p=0.002). QoL scores were comparable to the Portuguese pediatric population, but treatment delays were linked to lower total QoL (r=-0.45, p=0.002), particularly in emotional and social domains. Conclusion: Early thyroid hormone therapy is essential to mitigate neurocognitive deficits and improve QoL in CH. While severe intellectual disabilities are rare, non-verbal deficits persist, emphasizing the need for timely treatment and continuous monitoring.