Bit · Behavioral
Personality Disorders — Clusters A, B, C
Ten personality disorders organized into three clusters. The pivot is the cluster (the overall flavour) before the specific diagnosis.
Mechanism
Personality disorders are enduring patterns of inner experience and behaviour that deviate from cultural expectations, are pervasive across situations, begin by early adulthood, and cause distress or impairment. DSM organizes them by cluster:
- Cluster A — 'weird' — odd, eccentric. Genetic link to schizophrenia spectrum.
- Cluster B — 'wild' — dramatic, emotional, erratic.
- Cluster C — 'worried' — anxious, fearful.
Differentiator Table
| Cluster | Disorder | Hallmark |
|---|---|---|
| A — weird | Paranoid | Pervasive distrust and suspicion of others' motives |
| A — weird | Schizoid | Voluntary social withdrawal, restricted emotional range, prefers solitude (different from schizotypal — no odd thinking) |
| A — weird | Schizotypal | Odd thinking, magical thinking, ideas of reference, eccentric behaviour (without overt psychosis) |
| B — wild | Antisocial | Disregard for + violation of rights of others; conduct disorder before 15; M>F; lying, stealing, aggression |
| B — wild | Borderline | Unstable relationships, identity, affect; splitting; suicidal/self-harming gestures; fear of abandonment; F>M |
| B — wild | Histrionic | Excessive emotionality, attention-seeking, theatrical, inappropriately sexually provocative |
| B — wild | Narcissistic | Grandiosity, need for admiration, lack of empathy, fragile self-esteem |
| C — worried | Avoidant | Hypersensitive to rejection, socially inhibited, feels inadequate (different from schizoid — DESIRES relationships) |
| C — worried | Dependent | Submissive, clingy, fears separation, needs others to make decisions |
| C — worried | Obsessive-compulsive (OCPD) | Preoccupied with order, perfection, control; rigid; NOT obsessions/compulsions of OCD |
The Pivot
Two questions:
- What is the overall flavor? Weird (A), wild (B), worried (C).
- Within the cluster: distrust → paranoid. Voluntary loner → schizoid. Magical thinking → schizotypal. Lawbreaking with no remorse → antisocial. Splitting + self-harm + abandonment fear → borderline. Theatrical + seductive → histrionic. Grandiose + needs admiration → narcissistic. Wants connection but afraid of rejection → avoidant. Needs others to decide → dependent. Rigid + perfectionistic + ego-syntonic → OCPD.
Critical distinction: OCPD vs OCD. OCPD = personality style, ego-syntonic (patient doesn't see it as a problem). OCD = anxiety disorder, ego-dystonic (patient knows obsessions are intrusive).
NBME-Style Stem
A 26-year-old woman is seen for the third time in 4 months in the ED for superficial cuts on her forearms. She tells the resident he is the 'only doctor who has ever understood me' but tells the attending he is incompetent. She reports feeling 'empty' and was recently abandoned by her partner. Which of the following personality disorders is most likely?
Concept Anchor
Personality is the consistent way someone moves through the world. When that consistency itself causes harm, it's a personality disorder — and the cluster (weird, wild, worried) names the flavour before the specific label.