Diagnosing personality disorders
Why diagnose?
- Guides treatment decisions
- Reduces suffering and impairment
- Helps families and society manage impact
- Prevents misdiagnosis and stigma
Shift in diagnostic models
- Originally categorical (medical model)
- Issues: overlap, poor fit, rigid labels
- Shift toward dimensional models
DSM-5:
- Main system → categorical
- Alternative → AMPD (dimensional)
Categorical vs dimensional models
Core difference
| Model | Core idea |
|---|---|
| Categorical | Disorders are distinct categories |
| Dimensional | Traits exist on a continuum |
Key strengths and limitations
Categorical
- Simple, fast, widely used
- Clear communication
- High comorbidity
- Rigid, oversimplifies individuals
- Arbitrary thresholds (e.g. 4 vs 5 symptoms)
- Lower reliability
Dimensional
- More realistic and nuanced
- Captures individual differences
- Better for complex cases
- Complex and time-consuming
- Harder to communicate
- Requires training
Antisocial personality disorder (ASPD)
Core idea
Disregard for others’ rights and social norms
Diagnostic pattern
- Conduct disorder before age 15
- Persistent rule-breaking (aggression, destruction, theft)
- Chronic law-breaking
- Arrests, criminal activity across life
- Deceit and manipulation
- Lying, conning, exploiting for gain
- Impulsivity and aggression
- Fights, assaults, risk-taking
- Recklessness and irresponsibility
- Failure to work or meet obligations
- Lack of remorse
- No guilt, blame-shifting
Borderline personality disorder (BPD)
Core idea
Instability in relationships, self, emotions, and impulse control
Diagnostic pattern
- Fear of abandonment
- Clinging, desperate behaviour
- Unstable relationships
- Idealisation → devaluation
- Identity disturbance
- Unstable self, shifting values/goals
- Impulsivity and self-harm
- Risky behaviours, self-harm, suicidality
- Affective instability
- Rapid mood swings, intense emotions
- Chronic emptiness
- Anger and paranoia
- Poor control, stress → paranoia or dissociation
ASPD vs BPD
| Feature | ASPD | BPD |
|---|---|---|
| Core issue | Disregard for others | Emotional instability |
| Motivation | Goal-driven | Emotion-driven |
| Relationships | Exploitative | Intense, unstable |
| Harm pattern | Toward others | Toward self |
| Self-image | Stable (antisocial) | Unstable |
Symptom overlap and comorbidity
Shared features
- Impulsivity
- Emotional volatility
- Unstable relationships
- Risky behaviour
- Conflict
→ makes disorders hard to distinguish
Key distinction
- ASPD → goal-driven, self-serving behaviour
- BPD → emotion-driven, fear-based behaviour
Comorbidity and challenges
- Disorders often co-occur
- Symptoms can overlap, mask, or intensify each other
- Diagnosis is complicated by:
- Gender bias (BPD in women, ASPD in men)
- Clinician bias
- Stigma
→ misdiagnosis can lead to poor treatment outcomes
Psychopathy
Core features
- Manipulative behaviour
- Emotional detachment
- Callousness (low empathy)
- Impulsivity
- Persistent antisocial behaviour
Key insight
- Not limited to criminals
- Can appear in everyday and professional contexts
Prevalence
- ~1.2–4.5% general population
- ~20–40% in prisons
Psychopathy vs ASPD
| Feature | Psychopathy | ASPD |
|---|---|---|
| Focus | Emotional + interpersonal | Behavioural |
| Empathy | Absent | Not required |
| Scope | Narrow, severe subtype | Broader category |
| Diagnosis | Not DSM-5 | DSM-5 diagnosis |
Key idea
Psychopathy = more severe subset within ASPD
Primary vs secondary psychopathy
| Feature | Primary | Secondary |
|---|---|---|
| Cause | Biological | Environmental |
| Emotion | Low | High, unstable |
| Behaviour | Calculated | Reactive |
| Stability | Stable | Unstable |
Aetiology of psychopathy
Overview
- Combination of biological and environmental factors
- Links to primary vs secondary distinction
Biological (primary)
- Amygdala differences (emotion processing)
- Reduced fear and empathy
- Fearless dominance → risk-taking
→ traits are innate and stable
Environmental (secondary)
- Trauma, adverse experiences, chronic stress
- Leads to emotional dysregulation and impulsivity
→ traits are acquired and reactive
Evidence and limitations
- Mostly correlational → cannot confirm causation
- Brain differences observed but direction unclear
Epigenetics
- Environment can alter gene expression
- Shows interaction between nature and nurture
Physiological evidence (GSR)
- Normal: threat → increased arousal
- Psychopathy: reduced physiological response
→ supports low fear and emotional deficits
PCL-R (psychopathy checklist)
| Dimension | Focus | Traits |
|---|---|---|
| Interpersonal | Social interaction | Charm, manipulation |
| Affective | Emotion | No empathy, no remorse |
| Lifestyle | Behaviour | Impulsivity, irresponsibility |
| Antisocial | Rule-breaking | Criminal behaviour |
Assessment methods
- Semi-structured interview
- In-depth but subjective
- Collateral records
- Objective, improves reliability
- Self-report
- Unreliable due to deception
→ best used in combination
Predictive value
- High PCL-R scores linked to:
- Higher recidivism
- More severe crime
- Faster reoffending
→ strong predictive validity in forensic settings
Ethical issues
- Labelling can bias legal decisions
- Risk of deterministic thinking
- Reduced rehabilitation opportunities
Core tension
Public safety vs individual rights
Diagnostic models in practice
Clinical implications
Categorical
- Standardised treatment
- Easy communication
- Widely supported for access
Dimensional
- Personalised treatment
- More flexible
- Harder to implement
