Dissociative and Somatoform Disorders

1. Overview & Epidemiology

Two families, one root idea: psychological distress expressed as bodily or mental dysfunction without a sufficient organic cause.

Dissociative disorders = involuntary disruption of the normal integration of consciousness, memory, identity, perception, affect, and behaviour. Spectrum from normal (daydreaming) to severe (loss of identity).
Somatoform / Somatic symptom disorders = physical complaints driving distress and over-use of medical services, disproportionate to or unexplained by organic disease. Lecture term: "chronic neurosis."

Disorder	ICD-10 / DSM-5-TR	Core feature	Approx. prevalence
Dissociative amnesia (± fugue)	F44.0 / F44.1	Psychogenic memory loss for autobiographical info	~1–2%
Dissociative identity disorder (multiple personality)	F44.81	≥2 distinct personality states + amnestic gaps	~1%
Depersonalization / Derealization disorder	F48.1	Persistent detachment from self / surroundings	~1–2%
Somatic symptom disorder (was somatization / Briquet)	F45.1	Multiple somatic symptoms + excessive health behaviour	~5–7%
Illness anxiety disorder (hypochondria)	F45.21

Sex: somatization, conversion, and DID are more common in women (roughly 2–3:1). Hypochondriasis is roughly equal.
Risk factors: childhood trauma/abuse (especially DID, dissociative amnesia, conversion), acute psychotrauma or interpersonal conflict, female sex, low socioeconomic status, alexithymia.
Ganser syndrome — classified as an "other dissociative disorder" (a dissociative reaction / hysterical pseudodementia), classically described in prisoners awaiting trial. Tetrad: approximate answers (Vorbeireden — e.g. 2+2 = 5), clouding of consciousness, pseudohallucinations, (conversion) somatic/amnestic features.