About This Page
This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Cluster A: paranoid, schizoid, schizotypal
- Cluster B: antisocial, borderline, histrionic, narcissistic
- Cluster C: avoidant, dependent, obsessive-compulsive personality disorder
- Patterns are enduring, inflexible, pervasive, impairing, and not due to substances/medical illness
- Psychotherapy is foundation; DBT is high-yield for borderline personality disorder
Overview
Personality disorders involve maladaptive patterns in cognition, affectivity, interpersonal functioning, and impulse control. They are pervasive across contexts, stable over time, and traceable to adolescence/early adulthood. Diagnosis should not be made during intoxication, mania, psychosis, delirium, or a transient crisis.
Epidemiology
Personality disorder traits are common in clinical settings and coexist with depression, anxiety, PTSD, substance use, eating disorders, and self-harm. Trauma is common but not required. Structured boundaries and validation improve care.
Clinical Features
Symptoms
Paranoid: mistrust/suspicion without fixed psychotic delusions
Schizoid: detachment and restricted emotional expression
Schizotypal: odd beliefs, magical thinking, eccentricity
Borderline: instability, abandonment fear, impulsivity, self-harm, emptiness
Antisocial: disregard for rights since 15; age >=18 and conduct disorder before 15
Avoidant/dependent/OCPD: rejection sensitivity, need to be cared for, perfectionistic control
Signs
Splitting, idealization/devaluation, suspiciousness, seductiveness, entitlement, dependency
Self-injury scars, impulsive injuries, intoxication, crisis presentations
Odd appearance, magical thinking, eccentric speech
Rigid perfectionism and distress when control is lost
Investigations
First-line
Longitudinal assessmentEnduring pattern since adolescence/early adulthood, across contexts, not limited to mood/psychosis/substance/crisis
Safety assessmentSelf-harm, suicide, violence, impulsivity, exploitation, substance use
Comorbidity assessmentMood, anxiety, PTSD, eating disorders, ADHD, SUD, psychosis
Second-line
Collateral/recordsRelationships, work/school, legal history, hospitalizations, therapy response
Structured interviewsSCID-5-PD or specialist tools
Medical/substance evaluationWhen behavior change is new, episodic, or atypical
Specialist
PsychotherapyDBT for borderline; CBT/mentalization/schema/transference-focused depending on diagnosis
PsychiatryHigh-risk self-harm, severe comorbidity, diagnostic uncertainty, medication target symptoms
1
General management
- Consistent boundaries, clear treatment frame, crisis plan, coordinated team communication
- Validate distress without reinforcing maladaptive behavior
- Treat comorbid mood, anxiety, PTSD, ADHD, eating, and substance use disorders
2
Borderline personality disorder
- DBT for chronic suicidality, self-harm, emotional dysregulation, impulsivity
- Medications target comorbidity/short-term symptoms, not core BPD
- Hospitalization for acute imminent risk, not chronic risk alone
3
Cluster pearls
- Antisocial: safety, SUD treatment, boundaries; conduct disorder before 15 required
- OCPD: ego-syntonic perfectionism/control; distinguish from OCD
- Avoidant/dependent: CBT/exposure, social skills, autonomy-focused therapy
Complications
- Suicide/self-harm:
- Substance use:
- Legal/interpersonal harm:
- Occupational impairment:
- Treatment fragmentation/splitting:
USMLE Step 2 CK Exam Tips
- 1Borderline: unstable relationships/self-image/affect, impulsivity, abandonment fear, self-harm
- 2Bipolar is episodic; borderline affective instability is reactive/interpersonal
- 3Antisocial requires age >=18 + conduct disorder before 15
- 4OCPD ego-syntonic; OCD ego-dystonic
- 5Schizotypal has odd beliefs but not persistent frank psychosis
- 6DBT is high-yield for borderline
practicetest your knowledge on personality disorders (cluster a, b, c overview)Apply what you've learnt with USMLE Step 2 CK-style questions from the iatroX Q-Bank — psychiatry and beyond.
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