Anosognosia: Not Just a Primitive Defense Mechanism


If only it were this easy...

If only it were this easy…

Anosognosia is a technical term that refers to a lack of awareness of deficit.   The hallmark is a puzzling inability to recognize major symptoms, such as paralysis on one side of the body, amnesia, or marked cognitive impairment/dementia.  A related phenomenon is anosodiaphoria, which is an emotional insouciance or indifference in the face of major neurologic symptoms–not to be confused with la belle indifference, which refers to a cheerful lack of concern about disabling symptoms when there is no medical explanation for them.

Anosognosia is often associated with frontal lobe and/or right hemisphere brain insult but other regions have been studied, including the anterior insula.  Some conditions commonly associated with anosognosia are traumatic brain injury (moderate to severe), stroke, and Alzheimer’s/other dementias. See the Jenkinson, Preston and Ellis (2011) review below for a nice summary; it includes a number of assessment techniques for the condition.

In its most dramatic presentations, patients may be utterly unable to report the most startling and obvious impairment: being densely paralyzed on one side of the body, or even blindness (!).  A normal variant, called “unrealistic optimism” has even been studied!  The most important thing to remember is that anosognosia is not the same as psychological “denial” or defense mechanism where one cannot admit to and cope with impairment (think: alcohol abuse).  Very commonly my patients’ families will express frustration that their loved one is “in denial” about the injury or illness, and their attempts to provide help or feedback have been met with resistance.  I try to reframe this difficulty as a neurologic symptom, because family members may be very reluctant to “override” a loved one’s wishes or press the issue if they feel it will cause emotional distress or insecurity.

Patients with anosognosia will often produce elaborate, if incorrect, explanations of their symptoms (confabulation).  In dementia, the explanation is typically a firm belief that decline is normal age-related cognitive change that does not affect independence.   I have seen patients with dementia who adamantly and cheerfully report total independence to all their doctors, but interview with a family member reveals they cannot cook, manage money, drive, or even dress without assistance.  (This is why I always for permission to interview a family member).

If you ask stroke patients whether they had a stroke, they might respond, “That’s what they told me….”     I remember a patient of mine with stroke and dense left hemiparesis who said– as she sat, leaning far over to one side, in a wheelchair in a hospital– that she was just fine, thank you very much.  I asked if she had any weakness.  She said no.  I asked if she could in fact move her left arm.  She said yes.  There was a long silence as she sat looking at me.  I asked her to move her left arm for me.  With an effortful expression, she tried, and of course nothing happened.  I asked her why her arm didn’t move.  She said, “Well, I didn’t eat breakfast this morning, so I’m feeling weak!”

As you can imagine, the presence of anosognosia presents a unique and serious challenge to examination and treatment of patients: basically because they cannot accurately report problems, monitor/modify errors, or realistically, participate fully in rehabilitation. After all, are you going to be motivated to improve and change when you cannot recognize underlying deficits?  Also, patients are unlikely to take appropriate safety precautions when they don’t recognize problems that increase risk.

Anosognosia is quite refractory to treatment, once the intial spontaneous brain recovery has exhausted itself.  I was talking to my husband once years ago about this fascinating syndrome, and he replied, “Can’t you just tell them, ‘I’m your doctor, so trust me on this- you have a problem,’?”  If only!  My patients would likely reply with gently reassuring comments about how it’s true they are not 100%, but hey, who is?

To help explain the sensation my patients must have, I often ask their family members to imagine completing neuropsychological testing, after which I sit down and inform them that based on their errors (and the fact they’d bounced a check in 2014 and had a fender-bender in 2013) I am recommending someone be appointed their legal guardian and they’d no longer be able to drive or manage a checkbook.  I suspect people with anosognosia feel a bit like this when we point out deficits: no matter how often I tell you my diagnosis or point out problems, you will not incorporate or believe what I am telling you–it just does not compute.  You may even protest, “Everyone bounces a check at some point!  Everyone has a fender -bender!” After which you will take out your car keys and screech out of the parking lot (despite my warning that you’d be unsafe behind the wheel).

There is some interesting research on rehabilitation for anosognosia, focusing on third-person perspective-taking (e.g. watching a video of yourself performing an act), improving motor skills, and even pharmacotherapy (Jenkinson, Preston & Ellis, 2011).  Many specialized rehabilitation centers are able to tailor a treatment plan to fit the needs of each patient, taking into account emotional functions, family interactions, and level of unawareness.



Gasquoine, P (2015) Blissfully unaware: anosognosia and anosodiaphoria after acquired brain injury. Neuropsychological Rehab, Feb 16, 1-25.

Jenkinson, P., Preston, C., & Ellis, S. (2011) Unawareness after stroke: review and practical guide to understanding, assessing and managing anosognosia for hemiplegia. Jrnl Clin Exp Neuropsychology, 33, 10, 1079-83.

Mak, E., Chin, R., Ng, L, Yeo, D & Hameed, S (2015) Clinical associations of anosognosia in MCI and AD. Int J Geriatric Psychiatry, March 9.

McKay, R., Buchmann, A, Germann, N, Yu, S & Burgger P (2014).  Unrealistic optimism and “nosognosia”: Illness recognition in the healthy brain.  Cortex, Dec, 61, 141-7.

McKay, R & Kinsbourne, M (2010)Confabulation, delusion and anosognosia. Cogn Neuropsychiatry,  Jan 15,1,288-318

Stone, J, Smyth, R., Carson, A, Warlow, C &  Sharpe, M (2006) La belle indifference in conversion symptoms and hysteria.  Brit Jrnl Psychiatry, March 188,  204-9.


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