In some instances heavy drinking actually causes mental illness. This usually indicates that the drinking problem is serious and of relatively long duration, and that a degree of neuroadaptation is already present (see Chapter 3). This chapter deals with the neuropsychiatric complications seen in individuals with drinking problems. It looks firstly at alcohol-related hallucinatory states as exemplifying conditions for which drinking or withdrawal of alcohol is of undoubted and central causality. Delirium tremens, alcohol hallucinosis and alcohol-induced psychotic disorder with delusions are considered, followed by a review of pathological intoxication and alcoholic blackouts. Finally, the Wernicke–Korsakoff syndrome, alcoholic pellagra encephalopathy and alcohol-related brain damage are discussed.

Transient hallucinatory experience

Transient hallucinatory experience deserves note for two reasons. First, it may herald the onset of delirium tremens or alcoholic hallucinosis, and can often give early warning of the likelihood of these much more serious illnesses. It may therefore be viewed as continuous with these states, rather than as an altogether discrete clinical entity. Second, it is important to be aware that transient hallucinations may occur without the illness progressing to either of the major presentations. The diagnostician who is unfamiliar with these transient phenomena may be tempted to record incorrectly that the patient has ‘suffered from DTs’, when this was not the case.

The essence of this condition is that the patient fleetingly and suddenly experiences any one of a variety of perceptual disturbances, often very much to their surprise and consternation, and with the episode then immediately over.