F00-F09: Organic, including symptomatic, mental disorders

F05: Delirium, not induced by alcohol and other psychoactive substances

Delirium not induced by alcohol and other psychoactive substances is a group of conditions that manifest as a sudden change in one's mental state, leading to confusion and altered consciousness. These conditions are characterized by difficulty concentrating, memory problems, altered sleep patterns, fluctuating levels of consciousness, and often, a blurred or distorted perception of the environment. While not caused by substances like alcohol or drugs, they might stem from a variety of other medical conditions like infections, withdrawal from certain medications, metabolic imbalances, or directly from a physical disease affecting the brain. These conditions often progress rapidly, usually over hours or days, and symptoms can worsen at night. Left unaddressed, they could lead to severe complications including long term cognitive impairment. The affected system is primarily the central nervous system, specifically the brain.