Patel PB, Apornpong T, Puthanakit T, et al. - Because children with perinatal HIV (pHIV) may have distinct long-term cognitive phenotypes, researchers used group-based trajectory modeling to identify clusters of children with pHIV following similar developmental trajectories and predictors of belonging to select cognitive trajectory groups. The study sample consisted of children (aged 4 to 17 years) with pHIV in Thailand and Cambodia. Using maximum likelihood estimation, the best fit of trajectory groups was determined. For each cognitive test, group-based trajectory analyses showed a 3-cluster classification, marked as high, medium and low scoring groups. Group-based trajectory modeling succinctly classifies cohort heterogeneity in pHIV cognitive results. Most trajectories have remained stable throughout age, suggesting that cognitive potential is likely to be determined at an early age except for a small subgroup of children who have shown developmental gains in select cognitive domains and may represent those with better cognitive reserve. Poverty and longer untreated HIV duration may predispose children with pHIV to cognitive development that is suboptimal.