Abstract
BACKGROUND: Prenatal polysubstance exposure is highly prevalent among individuals with fetal alcohol spectrum disorders (FASD), yet little research has examined how specific patterns of co-exposure relate to neuropsychological outcomes. While alcohol is a known teratogen, other substances such as opioids, stimulants, cannabis, and nicotine also disrupt neurodevelopmental processes. Prior studies often assess single substances in isolation, failing to reflect real-world exposure patterns. Identifying meaningful patterns of co-occurring exposures and their associations with neuropsychological outcomes is critical for advancing targeted assessment and intervention. METHODS: Latent class analysis was conducted on data from 635 youth with FASD (mean age of diagnosis 7.4 years, range 0.24-21.61) to identify distinct profiles of prenatal exposure to six substances: alcohol, nicotine, marijuana, opioids, cocaine, and other drugs. Class differences in neuropsychological functioning, postnatal experiences, and demographics were examined using the Bolck, Croon, and Hagenaars method. RESULTS: A three-class solution demonstrated best model fit (AIC = 3945.216, saBIC = 3970.790, aLRT = 18.521, p = .006). Classes comprised of an all-exposure (Class 1, 47%), mainly alcohol exposed (Class 2, 46%), and mainly opioid exposed (Class 3, 7%). Significant between-class differences emerged across domains of memory, motor speed, sensory processing, and child-reported anxiety (χ(2) = 9.264-42.659, p = .046-0.001). Class 2 demonstrated significantly greater neuropsychological challenges, while Class 3 demonstrated high sensory sensitivity and anxiety. Results also reveal caregiver disruption was more prevalent in Class 2. DISCUSSION: Findings highlight heterogeneity in neuropsychological outcomes based on distinct patterns of prenatal polysubstance exposures. Neuropsychological assessment remains essential for capturing this variability and informing individualized, exposure-responsive care.