Personality disorders, somatic symptom, dissociative and sexual disorders
This domain rewards pattern recognition across clusters and a precise distinction between symptom disorders, factitious disorder and malingering.
Core rules
- Cluster A (odd): paranoid, schizoid, schizotypal. Cluster B (dramatic): antisocial, borderline, histrionic, narcissistic. Cluster C (anxious): avoidant, dependent, obsessive-compulsive personality disorder.
- Borderline personality disorder: abandonment fear, identity disturbance, affective instability, impulsivity, recurrent self-harm, transient stress-related paranoia. The evidence-based psychotherapy is dialectical behaviour therapy; medication targets specific symptoms only and is not a treatment for the disorder itself.
- Antisocial personality disorder requires conduct disorder before age fifteen and diagnosis at eighteen or later, with disregard for and violation of others' rights.
- Somatic symptom disorder is defined by distressing symptoms plus excessive thoughts, feelings or behaviours about them, not by symptom count. Illness anxiety disorder involves high health anxiety with minimal somatic symptoms.
- Conversion disorder (functional neurological symptom disorder) shows genuinely incongruent findings; factitious disorder involves intentional symptom production for the sick role, while malingering has an external incentive (money, litigation, avoiding duty).
- Dissociative identity disorder involves two or more identities with amnesia; dissociative amnesia often follows trauma; depersonalization/derealization disorder involves detachment or unreality with intact reality testing.
- Sexual dysfunctions require symptoms for at least six months on at least 75% of occasions. Paraphilic disorders require distress, impairment or harm to others; atypical arousal alone is not a disorder. SSRIs commonly cause delayed ejaculation and reduced libido.
Worked example
A patient with recurrent admissions and numerous operations produces blood in the urine and welcomes invasive tests but denies secondary gain, and secretly takes anticoagulants. The intentional production without external reward points to factitious disorder, whereas pursuing compensation for the same presentation would point to malingering.
Traps
Calling self-harm attention-seeking; diagnosing a personality disorder in an acute episode; treating somatic symptom disorder with more investigations; confusing gender dysphoria with a paraphilic disorder.