Executive and adaptive function impacts long-term outcomes for adults with maple syrup urine disease.

Successful transition to independent adulthood requires intact executive and adaptive function. These neurocognitive domains are frequently impaired in inherited metabolic disorders (IMD), despite optimal management. For many IMDs, the impact of executive and adaptive dysfunction on long-term outcomes remains undefined. Standardized assessments linking neurocognitive status with functional outcomes are needed to improve prognostication and tailor support for affected emerging adults. Maple syrup urine disease (MSUD), a relatively prevalent IMD, is primarily diagnosed in the first week of life through newborn screening. Despite early intervention, executive and adaptive dysfunction persist. We designed a remote, interactive battery of neurocognitive and functional assessments for adults (≥21 years) with MSUD to correlate neurocognition and long-term outcomes. Participants were selectively recruited for racial, ethnic, socio-economic, and geographic diversity. Assessments completed by 28 adults with MSUD (82% diagnosed after symptom onset, 25% from minority communities) show a wide range in educational attainment, employment, and residence. Executive and adaptive function were significantly impaired in adults with MSUD compared to controls. Executive and adaptive deficits correlated negatively with educational attainment, employment, and obtaining skills needed for adult-oriented healthcare or independent living. Clinical history did not predict functional outcomes, but neurocognitive assessments suggest the benefits of pre-symptomatic diagnosis. Independent adulthood is attainable for individuals with MSUD. Routine assessment of neurocognition and interventions targeting executive and adaptive function may improve long-term functional outcomes in IMD.