Confusion (from Latin confusĭo, -ōnis, noun of action from confundere "to pour together", or "to mingle together" also "to confuse") is the state of being bewildered or unclear in one’s mind about something:
Medical term 
"Acute Mental Confusion" is used interchangeably with Delirium in International Statistical Classification of Diseases and Related Health Problems and Medical Subject Headings to describe a pathological degree in which it usually refers to loss of orientation (ability to place oneself correctly in the world by time, location, and/or personal identity) sometimes accompanied by disordered consciousness and often memory (ability to correctly recall previous events or learn new material). Confusion as such is not synonymous with inability to focus attention, although severe inability to focus attention can cause, or greatly contribute to, confusion. Together, confusion and inability to focus attention (both of which affect judgment) are the twin symptoms of a loss or lack of normal brain function (cognition). The milder degrees of confusion as pathological symptoms are relative to previous function. Thus (for example) a mathematician confused about manipulation of simple fractions may be showing pathology which would not be diagnosable in a person without training in this area. Thus, as with the case of delirium, the minor degrees of pathological confusion cannot be diagnosed without knowledge of a person's "baseline", or normal, level of mental functioning.
Signs and symptoms 
Confusion is a symptom, and it may range from mild to severe. The confused state may include jumbled or disorganized thought and unusual, bizarre, or aggressive behaviors. A person who is confused may have difficulty solving problems or tasks, especially those known to have been previously easy for the person and an inability to recognize family members or familiar objects, or to give approximate location of family members not present. As well, they may appear to be disoriented, drowsy, hyperactive, or anxious. In severe cases, the person may have hallucinations, feelings of paranoia, and a state of delirium.
Confusion may result from drug side effects.
Confusion may result from a relatively sudden brain dysfunction. Acute confusion is often called delirium (also called acute confusional state), although delirium also includes a broader array of disorders than confusion, e.g. inability to focus attention and various impairments in awareness and temporal and spatial orientation.
Confusion may also result from chronic organic brain pathologies such as dementia. In either case, confusion is usually associated with some degree of loss of ability to focus attention, but (as noted) the association is not invariable, especially for lesser degrees of impairment.
Many health problems may cause the syndromes of delirium or dementia. These syndromes may also occur together, and both of them usually include the symptom of confusion. Since mental function is extremely sensitive to health, the appearance of either a new confused state, or a new loss of ability to focus attention (delirium), may indicate that a new physical or mental illness has appeared, or that a chronic physical or mental illness has progressed (become more severe).
Differential diagnosis 
The most common causes of drug induced acute confusion are dopaminergic drugs used for Parkinson's disease, diuretics, tricyclic or tetracyclic antidepressants and benzodiazepines. The elderly and especially those with pre-existing dementia are at most risk for drug induced acute confusional states.
- thefreedictionary.com > confusion (redirected from mental confusion) Citing: Dorland's Medical Dictionary for Health Consumers. 2007 by Saunders, an imprint of Elsevier, Inc.
- Waters, Jo. "Why don't GPS warn you that statins can harm your memory?". Daily Mail.
- patient.co.uk > Acute Confusional State Writer: Dr Gurvinder Rull. Document ID: 1714. Document Version: 22. Document Reference: bgp2104. Last Updated: 13 Jan 2009
- Hufschmidt, A.; Shabarin, V.; Zimmer, T. (Dec 2009). "Drug-induced confusional states: the usual suspects?". Acta Neurologica Scandinavica 120 (6): 436–8. doi:10.1111/j.1600-0404.2009.01174.x. PMID 19804475.
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