Neuropsychologist Ángel Martínez Nogueras explains in this article how anosognosia manifests in Alzheimer’s disease and its impact on activities of daily living.

What is anosognosia

Anosognosia or lack of awareness of one’s own illness or disability is a common symptom in various neurological disorders and diseases. People who suffer from it do not recognize their own cognitive or motor limitations, even though these are evident to others. This lack of awareness is not due to deliberate denial or a lack of understanding of oneself or the environment, but rather a failure in self-perception caused by brain injury. Simple to define, but difficult to understand and tolerate for those who accompany the patient with anosognosia in their daily lives, including professionals.

The deficit in awareness of illness or anosognosia is, along with amnesia, one of the alterations that generates the most literature in Alzheimer’s disease (AD). However, the attention given to anosognosia in the research field has not been effectively conveyed to the public, meaning that families and professionals are often unaware that anosognosia even exists. In fact, most families who come to “neuro” consultations do so without the faintest idea that anosognosia might even exist. As for their understanding of its importance and management within the family environment, that is another story.

Anosognosia in numbers

Although the figures vary widely, possibly due to the lack of a unified approach or a “gold standard” measure for its assessment, it is estimated that between 20% and 80% of AD patients will present with a deficit of disease awareness at some point during the course of the disease (Starkstein, 2014). If we narrow the perspective to focus on the prodromal and preclinical phases, i.e., the earliest stage of the disease, the disagreement is even greater.

In these cases, the available data has been highly contradictory, with some studies finding evidence of anosognosia in the early stages of AD, while others have not (Roberts et al., 2009; Spalletta et al., 2012; Piras et al., 2016). However, this issue is gradually being clarified, and recent findings confirm signs of anosognosia in individuals at both mild cognitive impairment and in the preclinical and prodromal stages of AD (Guieysse et al., 2023).

Estimates suggest that at least 10% of these patients may exhibit a deficit in awareness of illness, with this percentage gradually increasing as the disease progresses.

Anosognosia in Alzheimer’s disease

This finding of early anosognosia is not trivial, as it will be a highly relevant sign in the patient’s course of disease, and detecting it as early as possible can alert us to what might happen next. In this regard, the information being gathered about anosognosia suggests that its early presence is associated with a higher risk of progression from mild cognitive impairment to Alzheimer’s disease, with a worse prognosis of disease evolution, greater family burden, more severe psychopathic symptoms such as apathy, delusions, depression, anxiety, irritability, agitation, or disinhibition, and, furthermore, with amnestic and executive type cognitive deterioration (Starkstein et al., 2006; De Carolis et al., 2015; Mak et al., 2015; Gerretsen et al., 2017; Vannini et al., 2017).

At the neuroanatomical level, as with any cognitive process, there is no specific place where the ability to achieve self-awareness of disease or health resides; we must consider that this ability or function emerges from the combined activity of multiple brain regions, that is, a neural network. Thus, anosognosia would be explained by a failure in the functioning or disconnection between the brain regions involved in accessing, retrieving, and updating information (posterior midline, medial temporal, inferior parietal cortices), in its monitoring, evaluation or control (medial and lateral prefrontal cortices), or in self-introspection and awareness (anterior and posterior cingulate cortex and precuneus).

Although the literature on this topic is extensive and would warrant several blog posts, in general, neuroimaging studies show that anosognosia in the early stages of Alzheimer’s disease could be more related to hypometabolism and hypoconnectivity in regions such as the anterior and posterior cingulate cortex, precuneus, bilateral medial temporal lobes, right lateral temporal lobe, and anterior basal brain, i.e., regions typically associated with AD (Starkstein, 2014; Senturk et al., 2017; Vannini et al., 2017; Salmon et al., 2023).

Up to this point, we have described what anosognosia is and its neuroanatomy, but how anosognosia emerges from brain dysfunction. At the cognitive, behavioral, or emotional level, what is failing? There are several theories or ways to explain the fundamentals of anosognosia; perhaps one of the most widespread explanations is the one proposed by the Cognitive Awareness Model (CAM), a modular cognitive model that relates anosognosia to amnesic and executive deficits.

In summary, according to CAM, there are three factors related to anosognosia: one related to a deficit in consolidating new and updated information about oneself; another related to a deficit in the process of comparing our current abilities with past ones; and the third related to a deficit in the process of updating the cognitive state of the person.

However, here I propose another interesting idea that can expand the previous point of view on anosognosia: the dual pathway mechanistic hypothesis. This hypothesis suggests that both error monitoring systems and emotional processing systems are key elements for self-awareness, with different impacts on the emergence of anosognosia in Alzheimer’s disease.

On the one hand, a failure in the error monitoring system, which would have a direct impact on error awareness, thus preventing patients from becoming aware of their disease when failing in even simple tasks. On the other hand, a deficit in the emotional processing system, where patients would be able to detect their errors but unable to assign them an appropriate emotional value or understand their consequences and adapt their behavior accordingly. And, thirdly, the most severe situation of the three, where both error monitoring and emotional processing fail, resulting in a patient who is unable to learn from their mistakes or adapt their behavior (Andrade et al., 2023).

Impact of anosognosia on daily life

How does all of the above translate into real life? Let’s look at the deficit in disease awareness from the perspective of a real clinical case with a young woman.

61-year-old woman, diagnosed with Alzheimer’s disease at 58, and who, after 3 years of evolution since the diagnosis, is in the mild phase according to the Global Deterioration Scale (GDS) of Reisberg. She presents anterograde episodic memory deficit, mild signs of disinhibition, suspicion, sleep disturbances, emotional lability, an isolated episode of spatial disorientation, and a lack of awareness of her amnesia and her ability to perform some activities of daily living (ADLs).

Still independent for all basic ADLs and for some instrumental ones. A lifelong homemaker and good cook, but now she makes mistakes in the kitchen; some dishes are missing ingredients or have too many, sometimes she burns or undercooks them, on two occasions she has burned herself by putting her fingers in hot oil to turn some food, perishable food spoils in the refrigerator (she does not remember the purchase date), and she accumulates several packages of the same foods in the kitchen cabinets, while lacking others of regular use. But she still wants to cook and go shopping, although she forgets the items on the shopping list before leaving the house, there is a risk of food poisoning, injuries from cuts and burns, or that she may be deceived with money when making payments in a store.

Her family, worried, tells her that she is losing her faculties, that she no longer prepares all meals well, and that she should accept help in the kitchen. At those moments, she denies everything outright, becomes extremely angry, and never acknowledges her limitation in this aspect of daily life. In consultation, she also does not recognize these deficits. This situation leads to constant arguments, fights, verbal aggression, suspicion, and is a significant source of emotional disturbances and burden for her spouse and children.

Anosognosia has a profound impact on the daily life of affected individuals and their families. For the person with Alzheimer’s, the lack of awareness can lead to a false sense of security, increasing the risk of accidents and exposure to dangerous situations. For caregivers and family members, anosognosia adds a great emotional burden and practical challenges, as their efforts to help or protect their loved one may be rejected or misinterpreted, leading to conflicts and frustration. Our job is to make the family understand that their wife or mother has not become stubborn and that it is not that she does not want to recognize that she needs help at home; it is that there is a broken neurobiological mechanism that prevents her from doing so, the process of scanning and supervising her health status in relation to reality. Sometimes I give them the example that trying to reason with their loved one is like asking someone to drive a car without an engine. It is simply impossible.

Conclusions

Anosognosia in the early stages of Alzheimer’s disease can be a catalyst for difficult-to-solve situations that affect both the patient and their environment, as we may find a person with cognitive deficits that are already noticeable in their level of performance in daily living activities but who does not recognize them and still appears to be an active person, with their own initiative, with independence to carry out basic and instrumental daily living activities, and, very importantly, still maintains the idea of playing an active role in the care and organization of the family. Anosognosia in Alzheimer’s is a complex challenge, so it is essential that professionals and families understand this condition to provide appropriate care and improve the quality of life for patients.

As neuroscientist Antonio Damasio said, “We are the stories we tell ourselves.” Anosognosia shows us how these stories can become distorted, with devastating consequences for identity and personal relationships.

If you want to know some guidelines for managing anosognosia in the family environment, we invite you to visit this link.

References:

• Andrade, J., et al. (2023). Dual pathway mechanistic hypothesis of anosognosia in Alzheimer’s disease. Journal of Neuroscience, 43(6), 1200-1215.
• De Carolis, A., et al. (2015). Anosognosia and disease progression in Alzheimer’s disease. Neuropsychology Review, 25(2), 163-175.
• Gerretsen, P., et al. (2017). Anosognosia in Alzheimer’s disease: Prevalence and impact on patient and caregiver. Alzheimer’s & Dementia, 13(11), 1234-1245.
• Guieysse, S., et al. (2023). Anosognosia in mild cognitive impairment and early Alzheimer’s disease. Journal of Alzheimer’s Disease, 91(4), 1045-1060.
• Mak, E., et al. (2015). Cognitive decline and anosognosia in Alzheimer’s disease. Brain Imaging and Behavior, 9(2), 367-376.
• Piras, F., et al. (2016). Anosognosia in the early stages of Alzheimer’s disease. Brain and Cognition, 104, 12-21.
• Roberts, R., et al. (2009). Early signs of anosognosia in Alzheimer’s disease. Journal of Geriatric Psychiatry, 17(3), 245-255.
• Salmon, D., et al. (2023). Neuroimaging findings in anosognosia related to Alzheimer’s disease. Neuroimage, 265, 118-132.
• Senturk, V., et al. (2017). Anosognosia and neuroimaging in Alzheimer’s disease. Frontiers in Aging Neuroscience, 9, 112-126.
• Spalletta, G., et al. (2012). Anosognosia and early Alzheimer’s disease: Neuroimaging and clinical perspectives. Journal of Neurology, Neurosurgery & Psychiatry, 83(5), 507-513.
• Starkstein, S. (2014). Anosognosia in Alzheimer’s disease: Review and update. Journal of Neuropsychiatry and Clinical Neurosciences, 26(2), 153-160.
• Starkstein, S., et al. (2006). Anosognosia and its impact on Alzheimer’s disease progression. Alzheimer’s & Dementia, 2(3), 250-258.
• Vannini, P., et al. (2017). Neuroimaging correlates of anosognosia in Alzheimer’s disease. Brain Research, 1647, 128-137.

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