Chapter 27: Consultation-Liaison Psychiatry/Psychosomatic Medicine

Consultation-liaison psychiatry represents the clinical intersection where psychiatric expertise addresses the psychological and behavioral dimensions of medical illness, encompassing assessment and treatment of mental health conditions in hospitalized and medically complex patients. This chapter traces the subspecialty's evolution from historical interest in mind-body relationships to its establishment as the first officially accredited psychiatric subspecialty in the United States, reflecting growing recognition that psychiatric comorbidity significantly influences medical outcomes and healthcare costs. The consultant psychiatrist performs comprehensive evaluation of delirium, mood disorders, anxiety syndromes, adjustment reactions, substance-related conditions, and decision-making capacity while collaborating with medical and surgical teams to integrate psychiatric care into overall treatment planning. Theoretical frameworks—including psychodynamic, behavioral, cognitive, and biopsychosocial models—provide conceptual foundations for understanding how psychological factors, stress responses, coping mechanisms, social support systems, and health behaviors interact with and influence medical illness trajectories. The epidemiology of psychiatric comorbidity in medical settings demonstrates elevated rates of mental health disorders among medically ill populations and documented associations with increased morbidity, mortality, and healthcare resource utilization. Specialized applications occur across multiple medical domains including intensive care units, oncology services, cardiology, neurology, obstetrics, and organ transplantation, where psychiatric intervention addresses distinct patient populations and clinical challenges. The chapter addresses critical ethical and legal considerations including informed consent procedures, evaluation of medical decision-making capacity, management of end-of-life situations, and resolution of conflicts among patients, families, and healthcare providers. Treatment approaches integrate pharmacological interventions with psychotherapeutic techniques, adapted for medically ill populations with attention to drug interactions and medical complexity, while emphasizing collaborative care models that enhance interdisciplinary coordination. Contemporary advances in psychosomatic medicine research illuminate stress biology, psychoneuroimmunology mechanisms, and behavioral interventions demonstrating measurable improvements in medical outcomes, positioning consultation-liaison psychiatry as fundamental to comprehensive, integrated healthcare delivery.