TRAJECTORY AND EFFECTS OF A NATURALISTIC DEVELOPMENTAL INTERVENTION WITH ENRICHMENT IN A CHILD WITH ASD AND HIGH ABILITIES: A LONGITUDINAL SINGLE-CASE STUDY

Abstract

Children with twice-exceptionality (2e) combining autism spectrum disorder (asd) and high intellectual ability (giftedness) constitute an understudied population and one of high complexity for both assessment and intervention. This study describes the developmental trajectory of a 2e child identified at 27 months and evaluates the feasibility and effects of a combined package of naturalistic developmental behavioral intervention (ndbi) plus gifted enrichment. The objective was to longitudinally characterize the cognitive, socioemotional, and adaptive profile and to estimate changes in social communication, engagement in high challenge tasks, and daily functioning, using a single-case design with three annual assessments (t1–t2–t3). A multiple-baseline within-participant design across contexts (home–school–clinic) and target behaviors was used. The intervention included naturalistic teaching, motivational reinforcement, curriculum compacting, and progressively challenging cognitive tasks, in addition to caregiver and teacher training; dose: one 60-minute weekly session and daily home practice. Primary measures were functional communicative acts, joint attention, active participation, and problem behaviors; the assessments included standardized scales (asd, development/cognition, adaptation). Results: at t1, asd support level 2 and minimally verbal language were documented; cognitive performance was equivalent to 30 months. At t2, support level 2 remained, with cognitive performance increasing to 54 months. At t3, asd support level 1 was observed with spoken language and a discrepant wppsi-iii profile (verbal iq = 94, performance = 122, full scale iq = 107; language = 126). The integration of session and assessment data suggests improvements in communication and engagement, with generalization across contexts. The ndbi-plus-enrichment combination appears to enhance engagement by aligning intense interests with higher-complexity demands, fostering opportunities for meaningful practice and natural reinforcement. Implications for individualized educational planning and home–school–clinic collaboration are discussed.