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.

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

The elderly, and especially those with pre-existing dementia, are most at risk for drug induced acute confusional states.

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