Domain adaptive uplift modeling across heterogeneous mental health cohorts

Predicting who will deteriorate under stress is important for targeting mental-health support; yet, treatment-effect models are rarely tested across populations. We evaluate a domain-adaptive neural uplift model on three heterogeneous cohorts-medical students, members of the general public under quarantine, and psychiatric patients (n = 2,624). The model combines a shared encoder, two potential-outcome heads, a domain discriminator, and an optional fairness penalty. We compare no-adaptation training with four domain-adaptation mechanisms under a leave-one-domain-out protocol, using AUUC and a semi-synthetic benchmark with known treatment effects. The model achieves positive uplift ranking in two cohorts, while the psychiatric cohort shows sign inversion of the effect proxy. Adaptation yields modest, tuning-sensitive gains over a strong baseline. These results clarify when domain adaptation helps treatment-effect ranking under distribution shift and inform cautious deployment across cohorts.