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Anosognosia: What is it, a History and it’s Neuropsychological Reality


Anosognosia is often an aspect that remains in the background when talking about neuropsychology. Therefore, this article aims to explain what it is, what it may be associated with and what implications it has in everyday life and in the clinic.

What is anosognosia?

Anosognosia, a neologism derived from the Greek words a (without), nosos (disease) and gnosis (knowledge), literally means “lack of knowledge of the disease”. That is, the perspective on certain limitations (cognitive, behavioral, emotional or functional) of the affected person differs from that of other people or from the results of objective tests. This can occur as a consequence of brain injuries resulting from acquired brain damage or neurodegenerative diseases (Mograbi and Morris, 2018).

This difficulty in perceiving limitations can cover several aspects: from believing that one can see when actually suffering cortical blindness due to damage to the occipital lobe (Anton-Babinski syndrome), not being aware of the forgotton shopping list, to demonstrating behaviors previously not displayed. Similarly, it should be noted that anosognosia can be partial, with the patient being aware of a particular disturbance but ignoring the others, or even minimizing the relevance of the problem.

A bit of history

The discovery of this peculiar condition dates back to 1914, when the French-Polish neurologist Joseph Babinski (you may also be familiar with the Babinski sign, the plantar reflex) was working with patients who had suffered a stroke in the right hemisphere and consequently suffered from left hemiplegia. In the translation of the original text into English by Langer and Levine (2014) it is commented that when one of the patients was asked to raise both arms, she raised the right arm without any problem and when it was her turn to raise the left arm she either did not answer or said that she had raised it. Evidently, she could not lift it, but she believed that she had done so.

In the 1914 article Joseph coined the term anosognosia, indeed, he added yet another word to this context: anosodiaphoria (indifference). He used this word to refer to the condition of those patients where hemiplegia was in force but where the importance of the paralysis passed into the background. In other words: being aware of their hemiplegia, they were completely unconcerned, they did not report any discomfort about it (Langer and Levine, 2014).

Many aspects remained in the air and from this arose a debate that dragged on for the past century: does anosognosia really exist or does the patient fake it? Does he or she deny it?

The debate between anosognosia and denial of the deficit

Our protagonist believed in the existence of anosognosia, although he did not know how to prove it. For him, it did not make much sense for a patient to pretend for months and months that his arm worked perfectly.

On the other hand, some authors posit that the denial of the deficit is explicable through the psychodynamic paradigm, relating the lack of awareness to resistances or defense mechanisms (Ramachandran, 1995; Sims, 2014). However, current neuroscientific perspectives bring to the table the fact that the use of defense mechanisms should be contextualized in patients whose anosognosia does not depend on neurocognitive alterations (Mograbi and Morris, 2018).

We now know that anosognosia is largely a neuropsychological reality and that certain brain lesions can lead to suffering from this condition. Moreover, there are neuroanatomical correlates that bring us closer to understanding it.

Neuroanatomical basis of anosognosia and its prevalence

Babinski alluded that anosognosia could be due to lesions in the right hemisphere and that sensory alterations could influence its existence (in fact, patients did not react to external stimuli in these extremities).

Today, it would be a mistake to determine that a specific lesion in a specific place can cause specific neuropsychological alterations. However, we can say that lesions in certain structures can promote the appearance of such alterations or lesions in various regions can be potentially associated with them.

As I commented above, the etiology of anosognosia is varied, with an incidence between 10 and 18% in patients who have suffered strokes and who present with hemiparesis, while it is considered that up to 81% of people diagnosed with Alzheimer’s disease suffer some type of anosognosia and 60% of those who present with mild cognitive impairment will also experience it (Acharya and Sánchez-Manso, 2018).

In the case of anosognosia for hemiplegia, although it is more frequent in right unilateral or bilateral lesions, the frequency of occurrence of anosognosia is similar in people with temporal, parietal or frontal (subcortical and/or cortical) lesions. However, the likelihood of anosognosia is higher in those with lesions at both frontal and parietal levels compared to lesions in other brain regions (Pia, Neppi-Modona, Ricci, & Berti, 2004).

A current systematic review (Mondragon, Maurits, & De Deyn, 2019) comments that in patients with mild cognitive impairment, the association between anosognosia and reduced perfusion in addition to activity in the frontal lobe and midline structures is common. Likewise, with regard to anosognosia in Alzheimer’s disease, the studies reviewed show reduced perfusion, activation and metabolism in cortical midline structures, with the same phenomenon being detected in parietotemporal structures in more advanced stages of the disease.

Implications in neuropsychological assessment and rehabilitation

First, in the neuropsychological evaluation, it is possible that given the anosognosia, the patient may question the procedure. “Why are you asking me so many questions?” a patient who came to be explored to start neuropsychological rehabilitation after a stroke used to say to me. Non-collaboration during the evaluation could hinder the evaluation and confrontation would not always be a solution (even though it is obvious, I will explain why later). For this reason, and given that the onset of anosognosia is very diverse, the tests to be administered should be adapted to the individual and unique situation of the patient when performing the neuropsychological evaluation. Therefore, it would be at the discretion of the professional how to approach the situation with the skills he/she has acquired in his/her experience.

Another situation that may occur during rehabilitation sessions is that the patient with memory problems (e.g., people with Alzheimer’s disease) may be unaware of the existence of memory deficits, and the greater the disease progression, the greater the likelihood of anosognosia (Hanseew et al., 2019). What happens with anosognosia associated with memory problems and the people who suffer from it (especially episodic memory) is that no matter how much you confront the patient about the existence of such difficulties, it is not productive, because they will feel worse and probably for the next session they will not remember what happened. In this sense, I recommend watching “When and how to approach anosognosia”, a video where the approach for people with Alzheimer’s disease and for those suffering from ACD is differentiated (Ruiz-Sánchez de León, 2020).

For all these reasons, we should not forget to inform and educate family members and caregivers, so that they take anosognosia into account, since it can be a source of conflicts where both the patient and the family member may feel bad. In this context, two important pillars to address this situation are: understanding and empathy. Both on the part of the relatives and the clinical neuropsychologist.

In summary, anosognosia is a faithful companion to acquired brain injury and neurodegenerative diseases, which we must take into account both in the assessment and in neuropsychological rehabilitation. The approach must be adapted to the patient and approached from a multidisciplinary perspective. Likewise, the family members themselves should be included and involved in the path towards improving the quality of life of the people we want to help.


Acharya, A. B., y Sánchez-Manso, J. C. (2018). Anosognosia. StatPearls Publishing: Treasure Island (Florida).

Hanseeuw, B. J., Scott, M. R., Sikkes, S. A., Properzi, M., Gatchel, J. R., Salmon, E., … y Alzheimer’s Disease Neuroimaging Initiative. (2020). Evolution of anosognosia in alzheimer’s disease and its relationship to amyloid. Annals of neurology87(2), 267-280.

Langer, K. G., y Levine, D. N. (2014). Babinski, J. (1914). Contribution to the study of the mental disorders in hemiplegia of organic cerebral origin (anosognosia). Traducido por K.G. Langer & D.N. Levine. Traducido del original Contribution à l’Étude des Troubles Mentaux dans l’Hémiplégie Organique Cérébrale (Anosognosie). Cortex; a journal devoted to the study of the nervous system and behavior61, 5–8.

Mondragón, J. D., Maurits, N. M., y De Deyn, P. P. (2019). Functional neural correlates of anosognosia in mild cognitive impairment and alzheimer’s disease: a systematic review. Neuropsychology review29(2), 139-165.

Mograbi, D. C., y Morris, R. G. (2018). Anosognosia. Cortex; a journal devoted to the study of the nervous system and behavior103, 385-386.

Pia, L., Neppi-Modona, M., Ricci, R., & Berti, A. (2004). The anatomy of anosognosia for hemiplegia: a meta-analysis. Cortex40(2), 367-377.

Ruiz-Sánchez de León, J.M. [LOGICORTEX Neuropsicología]. (2020, 2 de septiembre). ¿Cuándo y cómo abordar la anosognosia? [Archivo de vídeo]. Recuperado de

Ramachandran, V. S. (1995). Anosognosia in parietal lobe syndrome. Consciousness and cognition4(1), 22-51.

Sims, A. (2014). Anosognosia and the very idea of psychodynamic neuroscience (No. Ph. D.). Deakin University.

Recommended Bibliography

Orfei, M. D., Caltagirone, C., y Spalletta, G. (2009). The evaluation of anosognosia in stroke patients. Cerebrovascular diseases27(3), 280-289.

Starkstein, S. E. (2014). Anosognosia in Alzheimer’s disease: diagnosis, frequency, mechanism and clinical correlates. Cortex61, 64-73.

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