Clouding of consciousness

"Brain fog" redirects here. It is not to be confused with Brain fag or Mild cognitive impairment.

Clouding of consciousness, also known as brain fog or mental fog,[1][2][3][4][5] is a term used in medicine denoting an abnormality in the regulation of the overall level[6] of consciousness that is mild and less severe than a delirium. The sufferer experiences a subjective sensation of mental clouding described as feeling "foggy".[7]

Background

The term clouding of consciousness has always denoted the main pathogenetic feature of delirium since Greiner[8] first pioneered the term (Verdunkelung des Bewusstseins) in 1817.[9] The Diagnostic and Statistical Manual of Mental Disorders (DSM) has historically used the term in its definition of delirium.[10] However, the DSM-III-R and the DSM-IV replaced “clouding of consciousness” with “disturbance of consciousness” to make it easier to operationalize, but it is still fundamentally the same thing.[11] There now appears to be a trend among many doctors to redefine clouding of consciousness to be less severe than delirium on a spectrum of abnormal consciousness.[6][12][13][14][15][16][17] In this case, it can be said that clouding of consciousness is synonymous with subsyndromal delirium.[18]

Subsyndromal delirium differs from normal delirium by being overall less severe, lacking acuteness in onset and duration, having a relatively stable sleep-wake cycle, and having relatively stable motor alterations.[19] The significant clinical features of subsyndromal delirium are inattention, thought process abnormalities, comprehension abnormalities, and language abnormalities.[19] The full clinical manifestations of delirium may never be reached.[18] Among intensive care unit patients, subsyndromal subjects were as likely to survive as patients with a Delirium Screening Checklist score of 0, but required extended care at rates greater than 0-scoring patients (although lower rates than those with full delerium)[18] or have a decreased post-discharge level of functional independence vs. the general population but still more independence than full delirium.[19]

It is featured in such conditions as minimal hepatic encephalopathy (also known as subclinical hepatic encephalopathy or latent hepatic encephalopathy),[20] subclinical Wernicke's encephalopathy, candidiasis,[21] Lyme disease,[22] anaphylaxis,[23] intestinal tapeworms[24] and lupus erythematosus.[25] The condition whereby intestinal faecal toxins bypass the liver poisoning the brain causing clouding of consciousness used to be referred to as "autointoxication" but is now referred to as "hepatic encephalopathy".[26][27][28][29][30] Minimal hepatic encephalopathy reduces quality of life by impairing work activities, social interactions, and driving, but it does not affect basic daily life activities such as dressing, personal hygiene, eating, shopping, answering the phone, or taking public transportation.[20] Patients with MHE may even exhibit normal cognitive performances, but overall productivity may suffer from inattentiveness and fatigue secondary to attention abnormalities.[20]

Conventional doctors understudy and neglect subsyndromal delirium because they "expect" delirium to be severe and they prefer to dedicate their medical resources to managing the more immediate "life-threatening" problems.[31] They have a tendency to "psychologize" it and misdiagnose it as depression or apathy.[32] In fact, most clinicians believe that minimal hepatic encephalopathy is "irrelevant" in spite of some evidence indicating that the diagnosis may be important.[20]

In clinical practice there is no standard test that is exclusive and specific; therefore, the diagnosis depends on the subjective impression of the physician.[20] The DSM-IV-TR instructs clinicians to code subsyndromal delirium presentations under the miscellaneous category of "cognitive disorder not otherwise specified".[33]

Psychopathology

The conceptual model of clouding of consciousness is that of a part of the brain regulating the "overall level" of the consciousness part of the brain, which is responsible for awareness of oneself and of the environment.[6][34] Various etiologies disturb this regulating part of the brain, which in turn disturbs the "overall level" of consciousness.[35] This system of a sort of general activation of consciousness is referred to as "arousal" or "wakefulness".[34]

It is not necessarily accompanied by drowsiness, however.[32] Patients may be awake (not sleepy) yet still have a clouded consciousness (disorder of wakefulness).[36] Paradoxically, sufferers declare that they are "awake but, in another way, not".[37] Lipowski points out that decreased "wakefulness" as used here is not exactly synonymous with drowsiness. One is a stage on the way to coma, the other on the way to sleep which is very different.[38][39]

The sufferer experiences a subjective sensation of mental clouding described in the patient's own words as feeling "foggy".[7] One sufferer described it as "I thought it became like misty, in some way... the outlines were sort of fuzzy".[37] Others may describe a "spaced out" feeling.[40] Sufferers compare their overall experience to that of a dream because as in a dream consciousness, attention, orientation to time and place, perceptions, and awareness are disturbed.[41] Barbara Schildkrout, MD, a board-certified psychiatrist and clinical instructor in psychiatry at the Harvard Medical School described her subjective experience of clouding of consciousness, or what she also called "mental fog", after taking a single dose of the antihistamine chlorpheniramine for her cottonwood allergy while on a cross-country road trip. She described feeling "out of it" and being in a "dreamy state". She described a sense of not trusting her own judgment and a dulled awareness, not knowing how long time went by.[3] Clouding of consciousness is not the same thing as depersonalization even though both sufferers compare their experience to that of a dream. Psychometric tests produce little evidence of a relationship between clouding of consciousness and depersonalization.[42]

This may affect performance on virtually any cognitive task.[3] As one author put it, "It should be apparent that cognition is not possible without a reasonable degree of arousal."[6] Cognition includes perception, memory, learning, executive functions, language, constructive abilities, voluntary motor control, attention, and mental speed.[20] The most significant, however, are inattention, thought process abnormalities, comprehension abnormalities, and language abnormalities.[19] The extent of the impairment is variable because inattention may impair several cognitive functions.[20] Sufferers may complain of forgetfulness,[20] being “confused”,[20][43] or being “unable to think straight”.[43] Despite the similarities, subsyndromal delirium is not the same thing as mild cognitive impairment. The fundamental difference is that mild cognitive impairment is a dementia-like impairment,[20] which does not involve a disturbance in arousal (wakefulness).[44]


See also

References

  1. ↑ "Taber's Medical Dictionary".
  2. ↑ "fog". Dorland's Illustrated Medical Dictionary E-Book. Elsevier Health Sciences. 2011. ISBN 1455709859.
  3. 1 2 3 Barbara Schildkrout (2011). Unmasking Psychological Symptoms. John Wiley & Sons. pp. 183–184. ISBN 9780470639078.
  4. ↑ M. Basavanna (2000). Dictionary of psychology. Allied Publishers. p. 65. ISBN 8177640305.
  5. ↑ Svetolik P. Djordjevic, Svetolik P. Djordjević (2004). Dictionary of Medicine: French-English with English-French Glossary. Schreiber Pub. p. 77.
  6. 1 2 3 4 Plum and Posner's diagnosis of stupor and coma. Oxford University Press. 2007. pp. 5–6. ISBN 9780199886531.
  7. 1 2 Augusto Caraceni & Luigi Grassi (2011). Delirium: Acute Confusional States in Palliative Medicine. Oxford University Press. p. 82. ISBN 9780199572052.
  8. ↑ Georg F. Greiner (1817). Der Traum und des fieberhafte Irreseyn. F. A Brockhaus.
  9. ↑ Augusto Caraceni & Luigi Grassi (2011). Delirium: Acute Confusional States in Palliative Medicine. Oxford University Press. p. 2. ISBN 9780199572052.
  10. ↑ George Stein, Greg Wilkinson (April 2007). Seminars in General Adult Psychiatry. RCPsych Publications. p. 490. ISBN 1904671446.
  11. ↑ Dan G. Blazer & Adrienne O. van Nieuwenhuizen (2012). "Evidence for the Diagnostic Criteria of Delirium". Curr Opin Psychiatry 25 (3): 239–243.
  12. ↑ Dennis C. Tanner (February 2007). Medical-Legal and Forensic Aspects of Communication Disorders, Voice Prints, and Speaker Profiling. Lawyers & Judges Publishing Company. p. 95. ISBN 1933264136.
  13. ↑ Anthony David, Simon Fleminger, Michael Kopelman, Simon Lovestone, John Mellers (April 2012). Lishman's Organic Psychiatry: A Textbook of Neuropsychiatry. John Wiley & Sons. p. 5. ISBN 9780470675076.
  14. ↑ Walker HK, Hall WD, Hurst JW (1990). Clinical Methods: The History, Physical, and Laboratory Examinations. Butterworths. p. 296.
  15. ↑ Fang Gao Smith (April 2010). Core Topics in Critical Care Medicine. Cambridge University Press. p. 312. ISBN 1139489682.
  16. ↑ William Alwyn Lishman (1998). Organic Psychiatry: The Psychological Consequences of Cerebral Disorder Third Edition. John Wiley & Sons. pp. 4–5.
  17. ↑ George Stein, Greg Wilkinson (2007). Seminars in General Adult Psychiatry Second Edition. RCPsych Publications. p. 490.
  18. 1 2 3 Sébastien Ouimet; Riker, R; Bergeron, N; Cossette, M; Kavanagh, B; Skrobik, Y; et al. (2007). "Subsyndromal delirium in the ICU: evidence for a disease spectrum". Intensive Care Med 33 (6): 1007–1013. doi:10.1007/s00134-007-0618-y. PMID 17404704.
  19. 1 2 3 4 David Meagher; Adamis, D.; Trzepacz, P.; Leonard, M.; et al. (2012). "Features of subsyndromal and persistent delirium". The British Journal of Psychiatry 200 (1): 37–44. doi:10.1192/bjp.bp.111.095273. PMID 22075650.
  20. 1 2 3 4 5 6 7 8 9 10 M. Ortiz; Jacas, Carlos; Córdoba, Juan; et al. (2005). "Minimal hepatic encephalopathy: diagnosis, clinical significance and recommendations". Journal of Hepatology 42 (1): S45–S53. doi:10.1016/j.jhep.2004.11.028. PMID 15777572.
  21. ↑ Lisch S, Steudel WI. (1994). "Unusual course of candidiasis of the central nervous system". Dtsch Med Wochenschr. 119(1–2): 13–8. doi:10.1055/s-2008-1058655.
  22. ↑ P G E Kennedy (2004). "VIRAL ENCEPHALITIS: CAUSES, DIFFERENTIAL DIAGNOSIS, AND MANAGEMENT". J Neurol Neurosurg Psychiatry 75 (Suppl 1): i10–i15. doi:10.1136/jnnp.2003.034280. PMC 1765650. PMID 14978145.
  23. ↑ Ken Hillman, Gillian Bishop (March 2004). Clinical Intensive Care and Acute Medicine. Cambridge University Press. p. 108. ISBN 1139449362.
  24. ↑ Oscar H. Del Brutto (2012). "Neurocysticercosis: A Review". The Scientific World Journal 2012: 1–8. doi:10.1100/2012/159821. PMC 3261519. PMID 22312322.
  25. ↑ Mackay, Meggan (2015). "Lupus brain fog: a biologic perspective on cognitive impairment, depression, and fatigue in systemic lupus erythematosus.". Immunologic research. PMID 26481913. Lay summary.
  26. ↑ Ringrose Atkins (1894). "Report on Nervous and Mental Disease". The Dublin Journal of Medical Science 97: 154.
  27. ↑ Angelina G. Hamilton (December 1923). "Some Observations Of The Use Of Laxatives and Cathartics In Certain Types Of Mental Cases". The Institution Quarterly 14 (4): 10.
  28. ↑ Esther A. Davidson and W. H. J. Summerskill (October 1956). "Psychiatric Aspects of Liver Disease". Postgraduate Medical Journal 32 (372): 487–494. doi:10.1136/pgmj.32.372.487. PMC 2501102. PMID 13389012.
  29. ↑ W.J. Cash; McConville, P; McDermott, E; McCormick, PA; Callender, ME; McDougall, NI; et al. (2010). "Current concepts in the assessment and treatment of Hepatic Encephalopathy". QJM 103 (1): 9–16. doi:10.1093/qjmed/hcp152. PMID 19903725.
  30. ↑ Karin Weissenborn; Ennen, JC; Schomerus, H; Rückert, N; Hecker, H; et al. (May 2001). "Neuropsychological characterization of hepatic encephalopathy". Journal of Hepatology 34 (5): 768–773. doi:10.1016/S0168-8278(01)00026-5. PMID 11434627.
  31. ↑ Yudofsky & Hales (2008). The American Psychiatric Publishing textbook of neuropsychiatry and behavioral neurosciences (5th ed.). American Psychiatric Pub. p. 449. ISBN 1585622397.
  32. 1 2 Roger A. MacKinnon, Robert Michels, Peter J. Buckley (2006). The Psychiatric Interview in Clinical Practice 2nd edition. American Psychiatric Publishing, Inc. pp. 462–464.
  33. ↑ Augusto Caraceni & Luigi Grassi (2011). Delirium: Acute Confusional States in Palliative Medicine. Oxford University Press. p. 11. ISBN 9780199572052.
  34. 1 2 Augusto Caraceni & Luigi Grassi (2011). Delirium: Acute Confusional States in Palliative Medicine. Oxford University Press. pp. 19–21. ISBN 9780199572052.
  35. ↑ Yudofsky & Hales (2008). The American Psychiatric Publishing textbook of neuropsychiatry and behavioral neurosciences. American Psychiatric Pub. p. 477. ISBN 1585622397.
  36. ↑ Plum and Posner's diagnosis of stupor and coma. Oxford University Press. 2007. p. 8.
  37. 1 2 G Sorensen Duppils and K Wikblad (May 2007). "Patients' experiences of being delirious". Journal of Clinical Nursing 16 (5): 817. doi:10.1111/j.1365-2702.2006.01806.x. PMID 17462032.
  38. ↑ Lipowski ZJ. (1967). "Delirium, clouding of consciousness and confusion". Journal of Nervous and Mental Disease 145 (3): 227–255. doi:10.1097/00005053-196709000-00006. PMID 4863989.
  39. ↑ William Alwyn Lishman (1998). Organic Psychiatry: The Psychological Consequences of Cerebral Disorder. John Wiley & Sons. p. 4.
  40. ↑ Fred Ovsiew, M.D. (1999). Neuropsychiatry and Mental Health Services. American Psychiatric Press, Inc. p. 170. ISBN 0880487305.
  41. ↑ Simon Fleminger (2002). "Remembering delirium". The British Journal of Psychiatry 180 (1): 4–5. doi:10.1192/bjp.180.1.4. PMID 11772842.
  42. ↑ G. Sedman (1970). "Theories of Depersonalization: A Re-appraisal". The British Journal of Psychiatry 117 (536): 1–14. doi:10.1192/bjp.117.536.1. PMID 4920886.
  43. 1 2 John Noble, Harry L. Greene (1996). Textbook of Primary Care Medicine. Mosby. p. 1325.
  44. ↑ Plum and Posner's diagnosis of stupor and coma. Oxford University Press. 2007. p. 7. ISBN 9780199886531.
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