Organic Mental Disorders: Delirium, Dementia, and Amnestic Syndrome

1. Overview & Epidemiology

The unifying concept of an organic mental disorder (examiner favourite, from PSY 4.116):

• There is a causal relationship between the organic (somatic) disease and the psychopathology.
• The somatic pathology precedes the psychiatric symptoms.
• The course of the physical illness and the mental disorder run in parallel.
• A heteroanamnesis (collateral history from family/carers) is fundamental — alongside differential-diagnostic tests, not optional.

Delirium

• Definition (Debrecen): a disturbance of integration of consciousness with an organic background, involving **disorientation, hallucinations, psychomotor excitement, and ve