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17. Psychiatry

Learning Objectives

  • Identify the major categories of psychiatric disorders using DSM-5 diagnostic criteria
  • Distinguish between mood, anxiety, psychotic, and substance use disorders by their clinical features
  • Apply the biopsychosocial model to understand psychiatric illness across the lifespan
  • Evaluate patients for psychiatric emergencies including suicidality and acute psychosis
  • Select appropriate pharmacological and psychotherapeutic interventions for common conditions
  • Recognize how child and adolescent psychiatry differs from adult practice
  • Integrate US clinical guidelines (NIMH, APA, FDA) into safe, evidence-based psychiatric care

Quick Answer

Psychiatry is the medical specialty dedicated to diagnosing, treating, and preventing mental, emotional, and behavioral disorders. It draws on neuroscience, psychology, and medicine to understand conditions ranging from depression and schizophrenia to substance use disorders and developmental conditions in children. Psychiatrists use tools such as the DSM-5, structured clinical interviews, and rating scales alongside pharmacotherapy and psychotherapy. For USMLE purposes, mastering the major diagnostic categories, first-line treatments, and emergency management principles forms the core of what you need to know.

Topics at a Glance

TopicKey FocusImportance
Introduction to PsychiatryHistory, key concepts, diagnostic frameworks, essential skillsFoundation — establishes vocabulary and approach
Mood DisordersMDD, bipolar disorder, dysthymia; neurotransmitter basis; pharmacotherapyHigh-yield for USMLE Steps 1 and 2
Anxiety DisordersGAD, panic disorder, social anxiety, OCD; CBT and pharmacotherapyVery common in clinical practice and board questions
Psychotic DisordersSchizophrenia, schizoaffective disorder, brief psychosis; antipsychoticsCritical for understanding severe mental illness
Child and Adolescent PsychiatryADHD, ASD, conduct disorder; developmental contextIncreasing board relevance; distinct treatment considerations
Substance Abuse DisordersSUD classification, DSM-5 criteria, MAT, behavioral therapiesMajor US public health priority; high board yield
Psychiatric EmergenciesSuicidality, agitation, acute psychosis; risk assessment, de-escalationPatient safety; tested in clinical scenarios

Key Terms

TermDefinitionRelated Concept
DSM-5Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition; the standard US classification system for psychiatric diagnosesICD-11, diagnostic criteria
PsychosisA mental state involving loss of contact with reality, characterized by hallucinations or delusionsSchizophrenia, schizoaffective disorder
AffectThe observable expression of emotion during a clinical encounter; can be flat, blunted, labile, or restrictedMood, mental status examination
NeurotransmitterChemical messengers (serotonin, dopamine, norepinephrine) that regulate mood, cognition, and behaviorPsychopharmacology, mood disorders
Biopsychosocial modelA framework integrating biological, psychological, and social factors in understanding and treating mental illnessGeorge Engel, holistic care
Mood stabilizerMedications such as lithium or valproate used to prevent manic and depressive episodes in bipolar disorderBipolar disorder, lithium toxicity
Cognitive-Behavioral Therapy (CBT)A structured psychotherapy targeting maladaptive thought patterns and behaviorsAnxiety disorders, depression, OCD
Substance Use Disorder (SUD)A DSM-5 diagnosis based on a problematic pattern of substance use causing clinically significant impairmentTolerance, withdrawal, addiction
SuicidalityA spectrum of thoughts and behaviors related to self-harm or ending one's life; requires immediate risk assessmentPsychiatric emergencies, safety planning
AntipsychoticMedications that reduce psychotic symptoms; classified as first-generation (typical) or second-generation (atypical)Dopamine hypothesis, schizophrenia
Negative symptomsFeatures of schizophrenia reflecting loss of normal function — flat affect, alogia, anhedonia, avolitionPositive symptoms, schizophrenia
SSRISelective serotonin reuptake inhibitor; first-line pharmacotherapy for depression and many anxiety disordersFluoxetine, sertraline, MDD

Prerequisites: Basic neuroscience and neuroanatomy, pharmacology fundamentals, general internal medicine, medical interviewing skills

Related Topics: Neurology (especially epilepsy and dementia overlap), Pediatrics (developmental milestones), Geriatrics (late-life depression, dementia), Emergency medicine (overdose, agitation management), Endocrinology (thyroid disorders mimicking mood disorders)

Next Topics: Advanced psychopharmacology, Forensic psychiatry, Addiction medicine, Consultation-liaison psychiatry, Child and adolescent psychiatry subspecialty training