Dr. Castillo graduated summa cum laude from California Southern University. Her dissertation was titled, "The Evolution of Posttraumatic Stress Disorder Treatment: Lessons Learned from MDMA-Assisted Psychotherapy." Based on her research and clinical experience working with trauma, she developed the PACT model as an approach that highlights four cornerstones of effective therapy: Presence, Acceptance, Connection and Transcendence. An article on this approach was published in the Journal of Humanistic Psychology ("The PACT Model: Improving Outcomes in the Treatment of PTSD").

Dr. Castillo has presented twice at the International Summit on Violence, Abuse, and Trauma in San Diego, and completed a two-year fellowship at the Wright Institute in Los Angeles (WILA) in psychoanalytic psychotherapy, where she continues to guide students. Outside of supervision and clinical work, Dr. Castillo actively supports the research of Dr. Kate Chard, co-founder of Cognitive Processing Therapy for PTSD, and Director of PTSD Research Programs at the Cincinnati VA.