The response above synthesizes the most current evidence (including a 2026 network meta-analysis and the 2024 APA Practice Guideline for BPD) with authoritative textbook content. A few practical clinical notes worth emphasizing:

The most important single decision is sequencing - trying to treat ADHD with stimulants before stabilizing the BPD/NPD layer often fails and can worsen emotional instability. DBT must be established concurrently with any pharmacological approach.

For the sexual impulsivity specifically, the mechanism matters: in ADHD it reflects dopaminergic reward dysregulation + impaired inhibitory control; in BPD it reflects emotion regulation deficits and fear of abandonment; in NPD it reflects entitlement and grandiosity. The treatment must address all three pathways - pharmacologically (SSRI + mood stabilizer + ADHD medication) and psychotherapeutically (DBT skills + psychosexual work + schema/TFP for the NPD layer).