Study guide
Psychiatry accounts for roughly 10-15% of Step 2 CK items according to the official outline, a figure the testing organization can revise over time. These vignettes are built around DSM-5-TR-style diagnostic criteria and reward careful attention to symptom duration, functional impairment, and safety, since many psychiatric conditions look similar on the surface but are separated by a specific timeline or a single distinguishing feature. This chapter covers mood, anxiety, psychotic, substance use, and personality disorders, psychiatric emergencies, and psychopharmacology, framed as guideline-level, educational content rather than a substitute for professional clinical judgment.
Mood Disorders: Depression and Bipolar Spectrum
Major depressive disorder requires at least five of nine characteristic symptoms (including depressed mood or loss of interest as one of the five) present for at least two weeks, causing significant functional impairment, and not better explained by another condition such as substance use or a medical illness. The exam frequently tests the distinction between normal grief and a depressive episode: profound sadness after a loss is expected, but persistent hopelessness, guilt disproportionate to the loss, or suicidal ideation lasting well beyond the acute mourning period points toward a depressive disorder requiring treatment. Persistent depressive disorder (dysthymia) is distinguished by a longer duration (at least two years in adults) with milder, more chronic symptoms rather than the acute severity of a major depressive episode. Bipolar disorder vignettes hinge on recognizing mania or hypomania: a period of abnormally elevated, expansive, or irritable mood with increased energy, decreased need for sleep, grandiosity, pressured speech, and risky behavior. Mania is distinguished from hypomania by duration (at least one week versus at least four days) and severity, since mania causes marked impairment or requires hospitalization while hypomania does not. A classic trap is treating a bipolar patient's depressive episode with an antidepressant alone, which can precipitate a manic switch; guideline-level management instead favors mood stabilizers or atypical antipsychotics, often before or alongside any antidepressant. Recognizing bipolar disorder before selecting treatment for a depressive episode is one of the most consistently tested judgment calls in this section.
Anxiety, Trauma-Related, and Obsessive-Compulsive Disorders
Anxiety disorder vignettes are largely differentiated by the object and pattern of the fear. Generalized anxiety disorder involves excessive, difficult-to-control worry about multiple areas of life for at least six months, accompanied by physical symptoms like restlessness or muscle tension. Panic disorder involves recurrent, unexpected panic attacks (sudden surges of intense fear with physical symptoms peaking within minutes) followed by persistent worry about future attacks or a change in behavior to avoid them. Specific phobia and social anxiety disorder are distinguished by the narrow, specific trigger for the fear, such as heights or public speaking, versus generalized anxiety. Post-traumatic stress disorder requires exposure to a traumatic event followed by intrusive re-experiencing symptoms, avoidance, negative changes in mood or cognition, and hyperarousal, all lasting more than one month; symptoms in the first month after trauma that meet a similar pattern are classified as acute stress disorder instead. Obsessive-compulsive disorder is characterized by intrusive, unwanted obsessions paired with repetitive compulsions performed to reduce the anxiety the obsessions cause, and the exam expects you to recognize that these behaviors are time-consuming and distressing to the patient rather than pleasurable. First-line treatment across most of these conditions is typically a selective serotonin reuptake inhibitor or serotonin-norepinephrine reuptake inhibitor combined with structured psychotherapy such as cognitive behavioral therapy; benzodiazepines are generally reserved for short-term or as-needed use because of dependence risk, a distinction the exam tests directly.
Psychotic Disorders and Substance Use
Psychotic disorder vignettes are separated primarily by duration and the presence of mood symptoms. Brief psychotic disorder lasts less than one month, schizophreniform disorder lasts between one and six months, and schizophrenia requires continuous signs of disturbance for at least six months, with at least one month of active-phase symptoms such as delusions, hallucinations, disorganized speech, or negative symptoms like flattened affect. Schizoaffective disorder is distinguished from mood disorder with psychotic features by the presence of psychotic symptoms for a substantial period in the absence of a mood episode. The exam expects recognition that first-episode psychosis in a young adult warrants a medical and substance-use workup before settling on a primary psychiatric diagnosis, since intoxication, withdrawal, and certain medical conditions can mimic psychiatric psychosis. Substance use disorder vignettes test recognition of intoxication and withdrawal patterns: alcohol withdrawal can progress from tremor and anxiety in the first day to seizures and, in severe cases, delirium tremens with autonomic instability and confusion around 48 to 96 hours after the last drink, managed with benzodiazepines. Opioid withdrawal is uncomfortable (myalgias, rhinorrhea, dilated pupils, diarrhea) but not typically life-threatening, in contrast to alcohol or sedative-hypnotic withdrawal, which can be fatal without treatment. Recognizing which withdrawal syndrome is dangerous enough to require inpatient management is a frequently tested judgment call, as is distinguishing substance-induced symptoms from an independent psychiatric disorder based on whether symptoms persist well beyond the expected period of intoxication or withdrawal.
Personality Disorders and Psychiatric Emergencies
Personality disorder vignettes test recognition of enduring, pervasive patterns of thinking and behavior that begin by early adulthood and cause distress or impairment, grouped into three clusters: Cluster A (odd or eccentric, including paranoid, schizoid, and schizotypal), Cluster B (dramatic, emotional, or erratic, including borderline, narcissistic, histrionic, and antisocial), and Cluster C (anxious or fearful, including avoidant, dependent, and obsessive-compulsive personality disorder, which is distinct from OCD). Borderline personality disorder is tested through a pattern of unstable relationships, impulsivity, identity disturbance, and recurrent self-harm or suicidal gestures, often in response to perceived abandonment; dialectical behavior therapy is the guideline-level psychotherapy most associated with this condition. Psychiatric emergencies test triage judgment above all else. A patient expressing active suicidal ideation with a specific plan and access to means requires an immediate safety assessment and generally involuntary or voluntary hospitalization if they cannot be kept safe as an outpatient; a vague passive wish to be dead without intent or plan still warrants a thorough risk assessment but may allow outpatient management with close follow-up depending on the full clinical picture. Agitated or violent patients are managed with the least restrictive effective intervention first, escalating from verbal de-escalation to as-needed medication and physical restraint only when the patient poses an immediate danger, with careful documentation of the reasoning. Neuroleptic malignant syndrome, a rare but life-threatening reaction to antipsychotic medication presenting with fever, severe muscle rigidity, autonomic instability, and altered mental status, is a recurring emergency vignette requiring immediate discontinuation of the offending agent and supportive care.
Psychopharmacology Principles
Psychopharmacology questions test recognition of a drug class from its side-effect profile as much as its indication. Selective serotonin reuptake inhibitors are first-line for most depressive and anxiety disorders, with common side effects including gastrointestinal upset and sexual dysfunction, and a serious but rare risk of serotonin syndrome (agitation, hyperreflexia, clonus, hyperthermia) when combined with other serotonergic agents. Atypical antipsychotics are used for psychotic disorders and as adjuncts in mood disorders, with metabolic side effects (weight gain, dyslipidemia, hyperglycemia) as a major monitoring concern distinct from the movement-related side effects more associated with older, first-generation antipsychotics such as acute dystonia, akathisia, and tardive dyskinesia. Lithium, used for bipolar disorder, has a narrow therapeutic window and requires monitoring of drug levels, kidney function, and thyroid function, with toxicity presenting as tremor, confusion, and gastrointestinal symptoms that can progress to seizures at higher levels. Valproate and other mood stabilizers carry their own monitoring requirements, including liver function and, for valproate specifically, teratogenicity concerns relevant to reproductive-age patients. The exam expects you to match a described adverse effect (such as a tremor with a narrow toxic-to-therapeutic ratio) to the responsible drug class and to know the immediate next step, whether that is checking a drug level, stopping the medication, or providing supportive care, rather than simply naming the drug.
Key terms
- Major depressive episode
- — At least five of nine characteristic depressive symptoms for two weeks or more, causing significant functional impairment.
- Mania
- — At least one week of abnormally elevated or irritable mood with increased energy and impaired functioning, distinguishing bipolar I disorder.
- Hypomania
- — A milder, shorter (at least four days) version of mania that does not cause marked impairment or require hospitalization.
- Generalized anxiety disorder
- — Excessive, difficult-to-control worry about multiple life domains for six months or more, with associated physical symptoms.
- Post-traumatic stress disorder
- — Intrusive re-experiencing, avoidance, negative mood changes, and hyperarousal following trauma, lasting more than one month.
- Schizophrenia
- — A psychotic disorder with continuous signs of disturbance for at least six months, including one month of active psychotic symptoms.
- Delirium tremens
- — A severe, potentially fatal alcohol withdrawal syndrome with confusion and autonomic instability, typically 48 to 96 hours after last drink.
- Borderline personality disorder
- — A Cluster B personality disorder marked by unstable relationships, impulsivity, and recurrent self-harm, often treated with dialectical behavior therapy.
- Neuroleptic malignant syndrome
- — A rare, life-threatening reaction to antipsychotics causing fever, muscle rigidity, and autonomic instability, requiring immediate drug discontinuation.
- Serotonin syndrome
- — A toxic state from excess serotonergic activity, causing agitation, hyperreflexia, clonus, and hyperthermia, usually from combining serotonergic drugs.
- Lithium toxicity
- — Adverse effects from excess lithium levels (tremor, confusion, gastrointestinal symptoms, progressing to seizures), requiring level monitoring.
Exam tips
- Use symptom duration as the primary sorting tool for lookalike conditions: acute stress disorder versus PTSD, brief psychotic disorder versus schizophreniform versus schizophrenia.
- Before treating a depressive episode with an antidepressant alone, screen the stem for any history of mania or hypomania that would suggest bipolar disorder instead.
- Any explicit suicidal plan with access to means is a safety emergency in the vignette; do not select an outpatient follow-up answer in that scenario.
- Match side-effect patterns to drug classes (metabolic effects for atypical antipsychotics, narrow toxic window for lithium, serotonin syndrome risk for SSRIs) since many questions test recognition, not just naming.
- This content is educational and modeled on DSM-5-TR-style criteria for exam preparation; it is not a substitute for individualized clinical or diagnostic evaluation.