Medical providers divide altered mental status into three types: delirium, dementia, and psychosis: Delirium. Delirium is a change in mental function that often results in confusion and lack of awareness of the environment. Symptoms of delirium often set in rapidly. Dementia.

Three common broad classifications of AMS include delirium, dementia and psychosis (see Table 3). It is important to keep these in mind as you assess your patient because they have very different causes, treatments and dispositions.