The term "acute mental confusion"[1] is often used interchangeably with delirium[2] in the International Statistical Classification of Diseases and Related Health Problems and the Medical Subject Headings publications to describe the pathology.

These refer to the loss of orientation, or the ability to place oneself correctly in the world by time, location and personal identity.

Confusion may result from drug side effects or from a relatively sudden brain dysfunction.

These disorders include the inability to focus attention; various impairments in awareness, and temporal or spatial dis-orientation.

[8] New research is finding a link between vitamin D deficiency and cognitive impairment (which includes "foggy brain").