What is the pathophysiology of delirium, dementia, and amnesia?

Updated: Sep 19, 2018
  • Author: Richard D Shin, MD; Chief Editor: Gil Z Shlamovitz, MD, FACEP  more...
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Altered mental status can be divided into 2 major subgroups: acute (delirium or acute confusional state) and chronic (dementia). A third entity, encephalopathy (subacute organically based brain dysfunction), denotes a gray zone between these extremes; its early course may fluctuate and/or resolve, but it is often persistent and progressive.

The final common pathway of all forms of organically based mental status change is an alteration in cortical brain function, at times in concert with abnormalities of deep brain structures. These conditions result from (1) an exogenous insult or an intrinsic process that affects cerebral neurochemical functioning and/or (2) physical or structural damage to the cortex, subcortex, or to deeper structures involved with memory. Some of the etiologies include trauma, mass lesions, hydrocephalus, strokes (ie, multi-infarct dementia), atrophy, infection, toxins, or dementing processes.

The end result of these disruptions of brain function and/or structure is impairment of cognition that affects some or all of the following: alertness, orientation, emotion, behavior, memory, perception, language, praxis, problem solving, judgment, and psychomotor activity. Knowledge of which areas of this spectrum are affected or spared guides both the workup and the diagnosis.

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