Tag Archives: anosognosia

Can anosognosia help explain some public acts of violence?

Anosognosia has been traditionally discussed when explaining why patients with Alzheimer’s disease (Perrotin et al., 2005), Schizophrenia (Gerretsen et al., 2015), and various lesions (Moro et al., 2016) have resulted in the patient lacking awareness of the functional deficits associated with their disease or affliction. There are two competing models to explain anosognosia; a psychological model, which claims the individual is protecting themselves from the stress caused by their disease, and a neurological model, which posits that the lack of the patient’s insight into their own disorder is due to a failure of neurocognition (Lehrer & Lorenz, 2014). However, both models are in agreement that it is the disease that results in anosognosia: The disease results in the patient not recognizing they have the disease – or at least some symptoms of the disease.

Researchers are still vying for a comprehensive neurological profile of this lack of awareness, and even though the diseases and the injuries that are associated with anosognosia are diverse, there is overlap in the parts of the brain that are impacted. Patients with anosognosia have been found to have hypometabolism in the posterior cingulate cortex (PCC) (Perrotin et al., 2015; Therriault et al., 2018; Vannini et al., 2017), hypometabolism in the hippocampus (Vannini et al., 2016), and reduced gray matter in the anterior cingulate cortex (Spalletta et al., 2014). Some studies posit that reduced right hemispheric volume, which could occur through disease atrophy or injury, relative to the left hemisphere, particularly of the angular gyrus, the medial prefrontal cortex, the dorsolateral prefrontal cortex, insula, and anterior temporal lobe, lead to a lack of awareness in schizophrenic patients (Gerretsen et al., 2014).

To date, there appears to be little research on the prospect of anosognosia concomitantly occurring with an empathy or a moral deficit. This is surprising for two reasons. First, the aforementioned brain regions listed above, are also known to be involved in moral decision making (Baron-Cohen, 2012) and empathic responses (Alegria et al., 2016). Second, it is sometimes symptomatic of patients with Alzheimer’s Disease (Liljegren et al., 2016) and Schizophrenia (Del Bene et al., 2016) to behave violently towards others, which means that any anosognosia could extend to a patient’s unawareness of their own harmful behavior.


If an illness or a lesion results in both a loss of empathy or moral decision making, as well as the self-awareness of these, the behavioral intentions of the individual could change. This is extremely dangerous when the deficit is empathy, because empathy helps to inform humans about harmful behavior; if we observe another human in pain, most of us are able to recreate a sense or a feeling of that pain and thus feel that the behaviors and actions that have led to this are wrong. This mechanism can be behind our drive to prevent harmful behaviors and, and cause us to strive to ease the pain of others. If we stop or ease the pain of another individual, we prevent the need for an empathic response, and thus we stop or ease the empathic pain in ourselves.

The presence of an empathic response to seeing others in pain can thus lead to the stymieing of bad behaviors, not necessarily while they are being carried out, but even stopping them before they are carried out. The absence of an empathic response to pain could lead one to have the perception that some harmful behavior is okay, because this person is missing the internal response that would inform them otherwise. Our view of behaviors being right or wrong, due to our empathic response, will also shape our guiding philosophies and worldviews. If we feel that something is right or wrong, we tend to try and understand these feelings by providing a rationale, and this rationale contributes to our own moral code.


Anosognosia involving an empathy deficit could have a profound impact on the person’s life and their choices. Before the onset of anosognosia and the empathy deficit, the person might feel that certain behaviors are wrong, such as assault and violence; with empathy, these behaviors can be understood as deeply destructive, and function to prevent one engaging in them. The onset of anosognosia and an empathy deficit could lead to a person transitioning from feeling that a certain behavior is bad, to amoral or even good behavior.

Our sense of what is normal also informs our moral code and how we should treat others. Most people tend to think of themselves as rational and fair minded (even though some are open to considering the views of others), and so what they think as right or wrong about the world (including behavior) feels true because it has come from a balanced place. If a person was unaware that they had an empathy deficit, they would still consider themselves rational and fair minded, as they don’t recognize a deficit to undermine this view of themselves. This could mean as their moral code is subtly changing due to an absence of empathy, the change feels true, and thus right, further validating their new view of certain behaviors. If they attribute a recently adopted ideology to this shift in their view, the ideology, too, would be further validated.

A cursory glance at any number of manifestos, penned by murderers before they acted, will inform you of how the way they saw the world changed, and finally how this change brought on their actions, which they felt were necessary. A deliberate act of murder is clearly a failure of empathy, and one cannot help wondering if the murderer was even aware of their empathy deficit.


If an empathy deficit is observed in a patient, or individual, it is therefore of the utmost importance to understand if they recognize this deficit. A person who could understand that they have an empathy deficit, even if it’s temporal, could perhaps take measures to ensure they behave in an innocuous manner, through counseling, or through supervision by friends, family, or healthcare professionals.

It is also crucial to know if a person was aware of an empathy deficit before they acted destructively towards others, because it introduces accountability when the suspect is tried. In some cases of homicide, if mental illness, disorder, or mental illness is suspected, the prosecution often has to argue against a defense that claims the defendant was not accountable due to temporary or permanent insanity, or the defendant acted in a way that was out of their control, because of a clinical difference in brain or mental functioning. If it can be shown that the defendant was aware of their empathy deficit, the legal system could hold them accountable for their actions.

Jack Pemment © 2018



Alegria, A. A., Radua, J., & Rubia, K. (2016). Meta-analysis of fMRI studies of disruptive behavior disorders. American Journal of Psychiatry, 173(11), 1119-1130.

Baron-Cohen, S. (2012). The science of evil: On empathy and the origins of cruelty. Basic books.

Del Bene, V. A., Foxe, J. J., Ross, L. A., Krakowski, M. I., Czobor, P., & De Sanctis, P. (2016). Neuroanatomical Abnormalities in Violent Individuals with and without a Diagnosis of Schizophrenia. PLoS one, 11(12), e0168100.

Gerretsen, P., Menon, M., Mamo, D. C., Fervaha, G., Remington, G., Pollock, B. G., & Graff-Guerrero, A. (2014). Impaired insight into illness and cognitive insight in schizophrenia spectrum disorders: resting state functional connectivity. Schizophrenia research, 160(1), 43-50.

Gerretsen, P., Menon, M., Chakravarty, M. M., Lerch, J. P., Mamo, D. C., Remington, G., … & Graff‐Guerrero, A. (2015). Illness denial in schizophrenia spectrum disorders. Human brain mapping, 36(1), 213-225.

Lehrer, D. S., & Lorenz, J. (2014). Anosognosia in schizophrenia: hidden in plain sight. Innovations in clinical neuroscience, 11(5-6), 10.

Liljegren, M., Naasan, G., Temlett, J., Perry, D. C., Rankin, K. P., Merrilees, J., … & Miller, B. L. (2015). Criminal behavior in frontotemporal dementia and Alzheimer disease. JAMA neurology, 72(3), 295-300.

Moro, V., Pernigo, S., Tsakiris, M., Avesani, R., Edelstyn, N. M., Jenkinson, P. M., & Fotopoulou, A. (2016). Motor versus body awareness: Voxel-based lesion analysis in anosognosia for hemiplegia and somatoparaphrenia following right hemisphere stroke. Cortex, 83, 62-77.

Perrotin, A., Desgranges, B., Landeau, B., Mézenge, F., La Joie, R., Egret, S., … & Chételat, G. (2015). Anosognosia in Alzheimer disease: Disconnection between memory and self‐related brain networks. Annals of neurology, 78(3), 477-486.

Spalletta, G., Piras, F., Piras, F., Sancesario, G., Iorio, M., Fratangeli, C., … & Orfei, M. D. (2014). Neuroanatomical correlates of awareness of illness in patients with amnestic mild cognitive impairment who will or will not convert to Alzheimer’s disease. cortex, 61, 183-195.

Therriault, J., Ng, K. P., Pascoal, T. A., Mathotaarachchi, S., Kang, M. S., Struyfs, H., … & Gauthier, S. (2018). Anosognosia predicts default mode network hypometabolism and clinical progression to dementia. Neurology, 90(11), e932-e939.

Vannini, P., Hanseeuw, B., Munro, C. E., Amariglio, R. E., Marshall, G. A., Rentz, D. M., … & Sperling, R. A. (2017). Anosognosia for memory deficits in mild cognitive impairment: Insight into the neural mechanism using functional and molecular imaging. NeuroImage: Clinical, 15, 408-414.


Anosognosia, Psychopathy, and the Conscience

How people see and understand themselves is likely to have an impact on how they interpret interactions with others. Here, I briefly explore the brain areas implicated in anosognosia, how these areas are also relevant in psychopathy, and why anosognosia is important when considering the crime and the conscience.


Anosognosia is defined as the impaired ability of patients with neurological disorders to recognize the presence or adequately appreciate the severity of their deficits [1]. Torrey (2012) cites three examples of anosognosic patients; a stroke victim with a paralyzed arm claimed he couldn’t lift it because he had a shirt on; a woman with paralysis in her left arm was asked to raise it, and instead raised her left leg. When this was pointed out to her she responded that some people call it an arm, others a leg, and jokingly inquired as to the difference; the Supreme Court Justice, William Douglas, was paralyzed on his left side. He claimed this was a myth, and was still inviting people to go hiking [2].


Recent research on this phenomenon has identified deficits in the brain of the patients who in all honesty do not recognize that they are in some way impaired. By using fluorodeoxyglucose positron emission tomography (FDG-PET) and single photon emission computed Tomography (SPECT) Perrotin et al. (2015) found that anosognosic Alzheimer’s patients had a disruption in connectivity between the posterior cingulate cortex (PCC) and the orbitofrontal cortex (OFC) [1]. Ries et al. (2007) also implicated a compromised precuneus in anosognosic patients. These midline structures are susceptible to damage in those with Alzheimer’s Disease (AD) and stroke victims. Anosognosia is also experienced by schizophrenic patients; according to Gerretsen et al. (2015), 60% of schizophrenic patients experience moderate to severe illness awareness, and this can lead to medication non-adherence and poor treatment outcomes [4]; they found left hemispheric dominance in the left prefrontal cortex in anosognosic schizophrenic patients and cortical thinning in the temporoparietalocciptal junction (TPO).

There is still much work to be done to determine the mechanistic and functional basis of anosognosia, and to determine the subtleties between illnesses and disorders, but research is starting to identify suspect brain regions. This is useful if anosognosia is questioned in other disorders, because neurological studies exploring the disorder can be explored and legitimate avenues of scientific inquiry explored.


A failure to recognize a disorder is also present in those with psychopathy. While anosognosia is yet to be explored thoroughly in those with psychopathy, there are behavioral items on the Psychopathy Checklist (PCL-R) [5] that suggest anosognosia is present; grandiose sense of self-worth, lack of remorse, and failure to accept responsibility. The sense of self-worth and narcissistic traits of the psychopath clearly means that they think very highly of themselves. This negates the idea that the psychopath believes they suffer from a defect or a disorder; at the most they might recognize that most others are different, and perhaps inferior to themselves. If a lack of remorse is experienced, this is an explicit demonstration that they do recognize, at least on an emotional level, the consequences of their bad behavior as being wrong; if they do not believe their behavior is inappropriate, it stands to reason that they believe they behaved appropriately, and thus experience nothing ‘wrong’ about themselves. This aspect of self-belief and self-reflection is also seen in the psychopath’s failure to accept responsibility; if they are always good and right, there is little motivation to make amends.

Based upon this cursory examination of psychopathic behavior, it would seem reasonable to explore the neurological studies of psychopathy and see if there could be some overlap with previous studies on anosognosia, and in fact some of the same compromised brain areas are implicated. Many studies have demonstrated developmental differences in the PFC of the psychopath (for a review, see Umbach et al. (2015) [6]), and the white matter pathways, such as the uncinate fasciculus (UF) connecting to the PFC from the limbic regions [7]. Perrotin et al. [1] hypothesized that Anosognosia can result from a disruption in connectivity in the UF. When exploring connectivity in the frontoparietal network (FPN), Philippi et al. (2015) found reduced connectivity in those with higher scores on the PCL-R, which included the right precuneus. And to further the overlap, Glenn et al. (2009) [8] found that those with who scored high on the interpersonal factors of the PCL-R (manipulative, conning, deceitful), showed reduced activity in the PCC during an fMRI scan when having to make judgments during moral dilemma scenarios.

Anosognosia and psychopathy both demonstrate complex neurological constructs, and it is premature to conclude that the neurological basis for Anosognosia (itself still understood) would tuck neatly into the already known neurological research on the psychopath. However, given the neat juxtaposition of behavioral traits and neurological dysfunction, it is worth bringing psychopathy into discussions of Anosognosia for the following reason. The research on psychopathy is currently deeper and richer than the research on anosognosia, and behavior of the psychopath has been widely observed and studied. If we can reasonably conclude that psychopaths, particularly criminal psychopaths, are also anosognosics, their behavior can be assessed in light of what it means to recognize no disorder or defect within oneself. The parallel is further relevant with psychopathy when considering that a number of those with schizophrenia, and a minority of those with AD, have been known for antisocial, and sometimes criminal, behavior [9, 10].


Those with schizophrenia and AD also suffer from abuse, but when they have been known to act violently, their behavior and motivations need to be understood. Torrey (2012) has documented extensively the violent acts of those with schizophrenia [2]. There is usually a history of progressively worse episodes of psychosis that can convince the patient that they are receiving supernatural or alien instructions to kill or harm individuals, and more often than not family members. Whether or not the auditory hallucinations slowly convince the patient over time of the necessity for deadly action, or whether the act is impulsive, after the event the patient often remains remorseless and attributes their behavior to necessary and mandated (often divine) reasons. This state of mind is similar to the violent psychopath, who also viewed his violent actions as necessary and fully justified. The problem is never attributed to the self; a disorder or defect is not recognized. While psychopaths are widely regarded as not having a conscience and experience only limited affect, more research is needed on the experience of conscience by schizophrenics, especially understanding the role that psychosis played in circumventing the conscience and providing them with permission to act. It is also crucial to discover how those events are remembered and felt post psychosis, perhaps when the patient has reconvened their medication.

In illnesses and disorders that can be associated with antisocial behavior or aggression, anosognosia could be a partial reason for the event of the behavior. Not recognizing any problems or defects, and thinking that one acted rightly or righteously, will affect personal judgments on the self-evaluation of behavior. This does not provide a fertile ground for remorse or responsibility, and if the behavior was aggressive, the patient could continue to remain dangerous, inflexible to a reasoned and peaceful behavioral change. This makes the search for the neural representation of anosognosia all the more crucial, treatment all the more pressing, and methods of identification all the more necessary.

© Jack Pemment, 2016



  1. Perrotin, A. et al. (2015). Anosognosia in Alzheimer disease: Disconnection between memory and self‐related brain networks. Annals of neurology, 78(3), 477-486
  2. Torrey, E. F. (2012) The Insanity Offense, New York, W. W. Norton and Company
  3. Ries, M. L. et al. (2007). Anosognosia in mild cognitive impairment: relationship to activation of cortical midline structures involved in self-appraisal. Journal of the International Neuropsychological Society, 13(03), 450-461
  4. Gerretsen, P. et al. (2015). Illness denial in schizophrenia spectrum disorders. Human brain mapping, 36(1), 213-225
  5. Hare, R. D. et al. (1990). The revised Psychopathy Checklist: Reliability and factor structure. Psychological Assessment: A Journal of Consulting and Clinical Psychology, 2(3), 338-341
  6. Umbach, R. et al. (2015). Brain imaging research on psychopathy: Implications for punishment, prediction, and treatment in youth and adults. Journal of criminal justice, 43(4), 295-306
  7. Motzkin, J. C. et al. (2011). Reduced prefrontal connectivity in psychopathy. The Journal of Neuroscience, 31(48), 17348-17357
  8. Glenn, A. L. et al. (2009) The Neural Correlates of Moral Decision-Making in Psychopathy. Retrieved from http://repository.upenn.edu/neuroethics_pubs/55
  9. Fazel, S. et al. (2009). Schizophrenia and violence: systematic review and meta-analysis. PLoS Med, 6(8), e1000120
  10. Lopez, O. L. et al. (2003). Psychiatric symptoms vary with the severity of dementia in probable Alzheimer’s disease. The Journal of neuropsychiatry and clinical neurosciences, 15, 346–353