Shaffer, Rebecca C.

Abstract Objective Dravet syndrome (DS) is the prototypic developmental and epileptic encephalopathy, characterized by drug‐resistant seizures, developmental slowing, and many other morbidities. Detailed characterization of behavioral phenotypes and social–emotional skill development are limited. Methods We prospectively assessed behavioral and social–emotional problems in the ENVISION natural history study (NCT04537832) of children with DS associated with SCN1A pathogenic variants ( SCN1A + DS) enrolled at <5 years of age. Assessments every 3 months for up to 2 years included the Child Behavior Checklist (CBCL), Strengths and Difficulties Questionnaire (SDQ), Brief Infant‐Toddler Social and Emotional Assessment (BITSEA), and Vineland Adaptive Behavior Scales, 3rd Edition (VABS‐3). Results Fifty‐eight children with DS enrolled at 16 sites worldwide. Problematic behaviors—inattention, aggressive or oppositional behaviors, and withdrawn and autistic behaviors—began before age 3 years, became more evident with age, and were clinically significant in many children by age 3–4 years. CBCL Total, Externalizing, and Internalizing Problems T‐scores rose by approximately 3 points per year, and BITSEA Problem scale scores increased by 2.3 points annually ( p = .002). SDQ Hyperactivity scores worsened over time ( p = .013), whereas emotional difficulties remained stable. VABS‐3 Socialization domain scores, which were already more than 1 SD below the normative mean at baseline, decreased further, particularly in younger participants. Correlation analyses showed that poorer communication abilities were associated with increased problematic behaviors ( R = −.55 for CBCL Total Problems and VABS‐3 Communication scores). Mixed‐effects modeling identified age as the strongest predictor of worsening behavioral outcomes. Significance We found that behavioral and social–emotional problems are inherent components of DS that present in toddlerhood and worsen throughout early childhood. This highlights the need to diagnose and manage these issues early. Targeted therapy may alleviate the wide‐ranging morbidities that are intrinsic to DS, including the social–emotional and behavior problems that frequently emerge.

Abstract Objective Dravet syndrome (DS) is a developmental and epileptic encephalopathy characterized by drug‐resistant seizures and developmental slowing. Although cognitive and executive function deficits have been described, their early trajectory is not well understood. Methods The prospective ENVISION natural history study (NCT04537832) assessed cognitive, executive, and adaptive function in children younger than 5 years of age with SCN1A + DS every 6 months for up to 2 years using Bayley Scales of Infant and Toddler Development, 3rd Edition (BSID‐III), Wechsler Preschool & Primary Scale of Intelligence, 4th Edition (WPPSI‐IV), Vineland Adaptive Behavior Scales, 3rd Edition (VABS‐3), Behavior Rating Inventory of Executive Function – Preschool Version (BRIEF‐P), and Pediatric Evaluation of Disability Inventory (PEDI). Results Fifty‐eight children were enrolled, with 47% younger than age 2 years. At least 80% of children did not achieve age‐appropriate milestones. Mean BSID‐III Cognitive raw scores increased minimally, with age‐equivalent gains of only 3 months over 1.5 years. Mean Cognitive Composite scores declined significantly by Month 12 (from 81.6 to 72.2; change: –11.0, 95% confidence interval [CI]: −15.3 to −6.8), signaling a widening gap compared with neurotypical development. Executive function worsened, with mean BRIEF‐P Global Executive Composite T‐scores increasing by 3.2 points/year. For some participants, scores were 5 standard deviations (SD) above the normative mean, reflecting abilities profoundly below age expectations (bottom .00003% of the population). Adaptive functioning worsened, with mean VABS‐3 Adaptive Behavior Composite decreasing from 78.7 to 68.1 over 1.5 years (change: –9.0, 95% CI: −11.9 to −6.1) and greater decline among children <2 years at enrollment, with scores decreasing by ~15 points (1 SD). Over half of children >3 years could not remove clothing independently; and when placed on a toilet, 48% could not use it. Significance Infants and young children with SCN1A + DS show significant and progressive developmental slowing across several domains, highlighting urgent need for therapies to mitigate the devastating impact on individuals and families.