Written for Mind the Bleep by Dr Mamoor Waheed CT1
Reviewed by Dr Shajahan Ismail (Consultant Psychiatrist) and Dr Alexia Caramitsos-Tziras (Core trainee and Psychiatry co-lead for MTB)
Background
Personality disorders (PDs) are among the most misunderstood and mismanaged diagnoses in psychiatry. As a junior doctor, you will encounter patients with personality disorders across almost every setting: whether it’s an ED admission following self-harm, the ward during a medical admission, or even in outpatient clinics. Understanding them is not just academically useful, it can fundamentally change how you communicate, risk-assess, and plan care.
A personality disorder is defined as a deeply ingrained, pervasive pattern of inner experience and behaviour that deviates markedly from cultural expectations, is stable over time, and causes significant distress or functional impairment. Crucially, it is not caused by another mental illness, substance use, or medical condition however they can often co-exist.
Prevalence: Around 4–13% of the general population meets criteria for at least one personality disorder, rising to approximately 40–60% in inpatient psychiatric settings.
Aetiology: A Biopsychosocial Framework
| Domain | Key Factors |
| Biological | Genetic heritability (roughly 50% for BPD); amygdala hyperreactivity; HPA axis dysregulation; temperament |
| Psychological | Childhood trauma, abuse, neglect; disrupted attachment; invalidating environment (particularly in BPD) |
| Social | Poverty, instability, peer victimisation, chaotic family environments |
The ICD-11 Shift: What Changed?
The UK is transitioning from ICD-10 to ICD-11 (adopted by WHO in 2019, with NHS England implementing from 2022 onward). This is the most significant reclassification of personality disorders in decades and it’s worth understanding both systems, as clinical practice is still catching up.
ICD-10 is still widely used in clinical practice; it is a categorical model – patients were diagnosed with a specific named disorder based on meeting a threshold of criteria:
| ICD-10 Code | Personality Disorder |
| F60.0 | Paranoid PD |
| F60.1 | Schizoid PD |
| F60.2 | Dissocial PD |
| F60.30/31 | Emotionally Unstable PD (Impulsive/Borderline) |
| F60.4 | Histrionic PD |
| F60.5 | Anankastic (Obsessive-Compulsive) PD |
| F60.6 | Anxious (Avoidant) PD |
| F60.7 | Dependent PD |
| F60.8/9 | Other/Unspecified PD |
ICD-11 replaces the named categorical types (except for Borderline Pattern specifier) with a dimensional model built on two axes:
1. Severity Specifier: how much does it impair the person?
| Severity | Description |
| Personality Difficulty | Sub-threshold: traits cause some issues, but full PD criteria not met |
| Mild PD | Affects some areas of life |
| Moderate PD | Marked impairment across multiple domains |
| Severe PD | Pervasive impairment; significant risk to self or others |
2. Trait Domain Qualifiers: what kind of personality pathology?
Use “AND DA” to recall the five domains:
- Anankastia (rigidity, perfectionism, orderliness)
- Negative Affectivity (emotional instability, anxiety, worthlessness)
- Detachment (social withdrawal, emotional blunting)
- Disinhibition (impulsivity, recklessness, irresponsibility)
- Antisociality/Dissociality (callousness, manipulation, exploitation)
Plus, the retained Borderline Pattern specifier.
Why does this matter?
ICD-11 acknowledges that most patients don’t fit neatly into one category and that many have traits across multiple domains. It shifts the focus toward functional impairment rather than diagnostic box-ticking.
The DSM-5 Cluster System:
While the UK officially uses ICD coding, the DSM-5 Cluster A/B/C framework remains deeply embedded in clinical training, MRCPsych teaching, and ward rounds and is a practical working model.
- An easy way to remember the three clusters A,B and C is via “MBS”: Mad, Bad, Sad. But it’s very important to know that these labels are not clinical value judgements, they’re a memory tool.
These patients are not “mad,” “bad,” or “sad” as character flaws; they are people with significant distress and complex needs.
Cluster A:
- Paranoid Personality Disorder
Core feature: Pervasive, unjustified suspicion and distrust of others.
Mnemonic to make it easy to remember is SUSPECT:
- Spousal infidelity suspected without evidence
- Unforgiving (bears grudges)
- Suspicious of others’ motives
- Perceives attacks and reacts quickly with counterattack
- Enemy or friend? (suspects associates and confidents)
- Confiding in others feared (information may be used against them)
- Threats perceived in benign remarks or events
Clinical Presentation: Patients present as guarded, hostile, and sometimes litigious. They may have a history of frequent complaints against neighbours, employers, or previous treating teams, and interpret neutral events as personally threatening. They can be difficult to engage but consistency, transparency, and respecting their need for control improves rapport.
2. Schizoid Personality Disorder
Core feature: Profound detachment from social relationships and restricted emotional expression and crucially; the patient is not distressed by this.
Clinical Presentation: Often described as “loners” who genuinely prefer solitude. Unlike Avoidant PD, these patients do not crave connection. They may present incidentally during a medical admission, noted by nursing staff to be emotionally flat and to refuse family contact. Relationships, including romantic ones, hold little appeal.
- Key distinction: Schizoid PD = doesn’t want connection. Avoidant PD = desperately wants connection but is too fearful.
3. Schizotypal Personality Disorder
Core feature: Odd beliefs, magical thinking, and eccentric behaviour — without frank or sustained psychosis.
- ICD-10 note: Schizotypal disorder is classified under schizophrenia-spectrum disorders (F21), not as a PD in ICD-10. DSM-5 includes it as Cluster A. ICD-11 retains it as a separate entity.
Clinical Presentation: “I can sense when something bad is going to happen.” These patients may believe in telepathy, have odd and vague speech, or present with ideas of reference such as “that news report was directed at me.” Unlike schizophrenia, there are no sustained frank psychotic episodes. They sit on a schizophrenia spectrum and warrant monitoring for transition.
Cluster B:
- Antisocial Personality Disorder (ASPD)
Core feature: Persistent disregard for and violation of the rights of others. A history of conduct disorder before age 15 is required.
Mnemonic to make it easy to remember is CORRUPT:
- Cannot conform to law
- Obligations ignored
- Reckless disregard for safety of self or others
- Remorseless
- Underhanded (deceitful, lies, uses aliases)
- Planning insufficient (impulsive)
- Temper (irritable and aggressive)
The individual must be at least 18.
There must be evidence of conduct disorder with onset before age 15
Clinical Presentation: Commonly encountered in forensic settings, prisons, and liaison psychiatry. Patients may be charming and plausible, minimise serious events, or behave provocatively with staff. Psychopathy (assessed using PCL-R) overlaps with ASPD but includes additional features of superficial charm and callous-unemotional traits; it is not a formal ICD/DSM diagnosis.
🔴 Case Example: Marcus, 28, is referred to liaison psychiatry following a fight-related injury. He has 12 previous ED attendances, often alcohol related. He is charming, minimises the incident, and denies any problem. Old notes confirm childhood conduct disorder. He meets criteria for ASPD. He is not detainable under the MHA on this basis alone. A harm-reduction approach with substance misuse support is discussed with him.
2. Borderline Personality Disorder (BPD) / Emotionally Unstable PD (EUPD)
Core feature: Pervasive instability in self-image, affect, relationships, and impulse control — with frantic efforts to avoid abandonment.
Mnemonic to make it easy to remember is IMPULSIVE (requires ≥5 criteria):
- Impulsivity in ≥2 self-damaging areas (spending, sex, substances, reckless driving, bingeing)
- Moodiness (marked affective instability, usually lasting hours)
- Paranoia or dissociation under stress
- Unstable self-image (identity disturbance)
- Labile, intense relationships (rapid idealisation → devaluation)
- Suicidal gestures, threats, or recurrent self-harm
- Inappropriate, intense anger
- Vulnerability to abandonment (frantic efforts to avoid, real or imagined)
- Emptiness (chronic, pervasive)
Clinical Presentation: BPD is the most frequently encountered personality disorder in psychiatric services. Presentations to the ED following self-harm or overdose are common, often precipitated by perceived abandonment. Relationships with clinical teams can mirror interpersonal patterns: oscillating between idealisation (“you’re the only person who has ever understood me”) and devaluation (“you’re useless, just like the last doctor”).
🔴 Case Example: Sophie, 24, presents for the 8th time in 3 months following superficial self-laceration after her boyfriend “abandoned” her by going to work. MSE reveals labile affect, fleeting passive suicidal ideation, and chronic emptiness. There is a background of childhood trauma. Her crisis safety plan is reviewed and updated. She is referred for a DBT group. Inpatient admission is not offered — research and NICE guidance support community management, as prolonged admissions can reinforce crisis-based help-seeking in BPD.
3. Histrionic Personality Disorder
Core feature: Excessive emotionality and attention-seeking behaviour.
Clinical Presentation: Presentations may be dramatic or feel disproportionate to objective findings. Patients may become distressed if they are not the centre of attention and can be deeply suggestible. Speech is typically impressionistic, vague, and emotive rather than detailed. Functional neurological symptoms may co-occur.
4. Narcissistic Personality Disorder
Core feature: Grandiosity, an excessive need for admiration, and lack of empathy for others.
Clinical Presentation: Less frequently a primary psychiatric referral but commonly encountered in medical settings where patients demand special treatment, challenge clinical decisions, or make formal complaints when their sense of status is not acknowledged. Beneath the grandiose exterior often lies significant underlying fragility, shame, and vulnerability, this is the “thin skin under thick skin” phenomenon. Understanding this makes it easier to avoid power struggles.
Cluster C:
- Avoidant Personality Disorder
Core feature: Social inhibition, feelings of inadequacy, and hypersensitivity to negative evaluation
Mnemonic to make it easy to remember is CRINGES:
- Criticism preoccupies thoughts in social situations
- Restraint in relationships for fear of shame or ridicule
- Inhibited in new interpersonal situations
- Needs to be certain of being liked before engaging
- Gets around occupational activities requiring social contact
- Embarrassment prevents new activities or risk-taking
- Self-viewed as unappealing, inferior, or socially inept
Clinical Presentation: Commonly misidentified as social anxiety disorder (SAD). The key distinction: SAD is a specific, episodic anxiety disorder responsive to CBT and medication. Avoidant PD is a pervasive, lifelong pattern of personality functioning. The two frequently co-exist. Patients are often underemployed relative to their abilities and may have very restricted lives.
2. Dependent Personality Disorder
Core feature: Excessive reliance on others to meet emotional and practical needs, with profound fear of separation.
Clinical Presentation: Patients may remain in abusive or damaging relationships because the alternative of being alone feels intolerable. In clinical settings, they frequently defer all decisions and may seek reassurance repetitively. Transitions in care: discharge, change of keyworker, end of a therapeutic relationship; are all high-risk periods and warrant careful planning and gradual handover.
3. Obsessive-Compulsive Personality Disorder (OCPD)
Core feature: Preoccupation with orderliness, perfectionism, and control
Mnemonic to make it easy to remember is SCRIMPER:
- Stubborn
- Cannot discard worthless objects (hoarding tendency)
- Rule obsessed (inflexible about ethics, morality)
- Inflexible to change
- Miserly (reluctant to spend on self or others)
- Perfectionism interferes with completing tasks
- Excludes leisure (devotion to work and productivity)
- Reluctant to delegate unless things are done “their way”
OCPD vs OCD: This distinction trips up many students.
OCD = Ego dystonic. Obsessions feel alien and unwanted. The patient knows their thoughts are irrational and is distressed by them.
OCPD = Ego syntonic. The patient sees their perfectionism and rigidity as strengths, not problems. There are no intrusive obsessions or compulsive rituals as in OCD.
Management
Management requires a biopsychosocial approach, and above all, realistic expectations. There is no medication licensed specifically for any personality disorder. Personality disorders can improve with time and appropriate intervention; this is one of the most important misconceptions to correct amongst resident doctors/medical students.
Psychological Therapies (First Line)
| Therapy | Best Evidence For |
| Dialectical Behaviour Therapy (DBT) | BPD (gold standard); targets emotional dysregulation, distress tolerance, interpersonal skills, and mindfulness |
| Mentalisation-Based Therapy (MBT) | BPD; focuses on the capacity to understand mental states in oneself and others |
| Schema Therapy | BPD and general PDs; targets deep maladaptive schemas formed in childhood |
| Cognitive Analytic Therapy (CAT) | BPD and broader PDs; maps relationship patterns and their origins |
| CBT / Schema-Focused CBT | Avoidant, Dependent, OCPD |
| Transference-Focused Psychotherapy (TFP) | BPD, Narcissistic PD |
Pharmacological (Adjunct Only)
Medication targets comorbid conditions and specific symptom clusters, not the PD itself:
- SSRIs: Comorbid depression or anxiety; may modestly reduce impulsivity in BPD
- Low-dose antipsychotics (e.g., quetiapine): Transient psychotic-like episodes, severe emotional dysregulation. To only be used short-term and review regularly
- Mood stabilisers (e.g., lamotrigine): Affective instability; some evidence in BPD
- Avoid benzodiazepines in BPD as there is a risk of dependency, behavioural disinhibition, and paradoxical emotional worsening
Comorbidities to Consider
PDs rarely present in isolation. Common associations worth screening for:
- BPD: Depression, PTSD, eating disorders, substance misuse, ADHD
- ASPD: Substance use disorders, ADHD (look for childhood history of hyperactivity)
- Avoidant PD: Social anxiety disorder, depression
- OCPD: OCD (note the distinction above), depression, eating disorders
- Paranoid PD: Consider psychosis-spectrum risk; monitor for transition
Risk Assessment
Suicide risk is significantly elevated across PDs, particularly in patients with BPD; with lifetime suicide completion rates estimated at 8–10%. Key principles when risk-assessing:
- Distinguish chronic baseline risk from acute escalation above baseline
- Identify precipitants such as relationship breakdown, perceived rejection, anniversaries of trauma, transitions in care
- Explore the function of self-harm. For many patients, it is a coping mechanism, not an attempt to die. Treating it as purely suicidal can reinforce ED attendance and escalation
- Develop a collaboratively written crisis/safety plan
- Ensure clear follow-up with named contact and an agreed plan before discharge
Summary table
| Cluster A (“Mad”) | Cluster B (“Bad”) | Cluster C (“Sad”) | |
| Types | Paranoid, Schizoid, Schizotypal | ASPD, BPD, Histrionic, Narcissistic | Avoidant, Dependent, OCPD |
| Core Theme | Odd, eccentric, detached | Dramatic, impulsive, emotional | Anxious, fearful, over-controlled |
| Associated With | Psychosis spectrum | Trauma, impulse dysregulation | Anxiety disorders, depression |
| Key Therapy | Supportive/CBT | DBT, MBT, Schema Therapy | CBT, Schema Therapy |
Key Clinical Pearls
- PD ≠untreatable. This is one of psychiatry’s most damaging myths. Evidence for psychological therapy (particularly in BP) is strong and growing.
- Don’t diagnose in the acute phase. PD cannot be reliably diagnosed during a florid psychotic episode, severe depressive episode, or active intoxication.
- ICD-11 is coming. Familiarise yourself with severity specifiers and trait domain qualifiers; future documentation and discharge summaries will use this language.
- Language matters. Say “person with BPD/EUPD,” not “a borderline.” Language shapes how teams think about and treat patients
- Most patients have more than one PD. ICD-11’s dimensional model handles co-occurring pathology far more elegantly than ICD-10’s categorical system
Recommended media related to this area of interest
Psychiatry & Psychotherapy Podcast by Dr. David Puder.
- Available on: Spotify, Apple Podcasts, and psychiatrypodcast.com
Particularly relevant episodes for this article:
- Episode 115: Borderline Personality Disorder: History, Symptoms, Environment, Genetics & Brain Science
- Episode 206: Mentalisation-Based Therapy (MBT), featuring Dr. Anthony Bateman and Dr. Peter Fonagy – the two clinicians who developed MBT
- Episode 224: BPD Medications & Treatment: When and Why to Use Pharmacotherapy
The MBT episode with Bateman and Fonagy is particularly special as it’s rare to hear the originators of a therapy discuss it directly in such an accessible format.
References:
National Institute for Health and Care Excellence. Personality Disorders.
World Health Organization. Clinical Descriptions and Diagnostic Requirements for ICD-11 Mental, Behavioural and Neurodevelopmental Disorders (CDDR). Geneva: WHO; 2024.
