January 13, 2009
Some Deluded People Have Brain Injury

Brain injury in the frontal lobe and right hemisphere cause delusional beliefs.

A new study provides a novel theory for how delusions arise and why they persist. NYU Langone Medical Center researcher Orrin Devinsky, MD, performed an in-depth analysis of patients with certain delusions and brain disorders revealing a consistent pattern of injury to the frontal lobe and right hemisphere of the human brain. The cognitive deficits caused by these injuries to the right hemisphere, leads to the over compensation by the left hemisphere of the brain for the injury, resulting in delusions. The article entitled "Delusional misidentifications and duplications: Right brain lesions, left brain delusions" appears in the latest issue of the journal of Neurology.

"Problems caused by these brain injuries include impairment in monitoring of self, awareness of errors, and incorrectly identifying what is familiar and what is a work of fiction," said Dr. Devinsky, professor of Neurology, Psychiatry and Neurosurgery and Director of the NYU Epilepsy Center at NYU Langone Medical Center. "However, delusions result from the loss of these functions as well as the over activation of the left hemisphere and its language structures, that 'create a story', a story which cannot be edited and modified to account for reality. Delusions result from right hemisphere lesions, but it is the left hemisphere that is deluded."

Often bizarre in content and held with absolute certainty, delusions are pathologic beliefs that remain fixed despite clear evidence that they are incorrect. "Delusions are common problems in a variety of psychiatric and neurological disorders," said Dr. Devinsky. "Psychiatric disorders with delusions, for example- schizophrenia, have been proven to have functional and structural brain pathology. But now improved diagnostic techniques are allowing us to have increased identification of neurologic disorders among other patient populations with delusions."

In the study, the author finds that most neurologic patients with delusions usually have lesions in the right hemisphere and/or bifrontal areas. For example, the neurological disorders of Confabulation (incorrect or distorted statements made without conscious effort to deceive), Capgras (the ability to consciously recognize familiar faces but not emotionally connect with them) and Prosopagnosia (patients who may fail to recognize spouses or their own face but generate an unconscious response to familiar faces) result from right sided lesions.

I expect advances in understanding of brain disorders to cause legal battles. If someone is deluded and a danger to self or others should that person be forcefully treated with, for example, stem cells that will do brain repair? If the alternative is institutionalization in a prison or mental hospital is treatment without consent a better choice?

Many drugs already can alter mental state. If patients in mental hospitals are forceably drugged then already a person's own judgment about what is core to their identity - their own thoughts - is effectively rejected and replaced by the judgment of managers and experts in mental hospitals. The ramifications of this power will become greater as the technology for permanently altering cognitive function becomes more powerful.

Share |      Randall Parker, 2009 January 13 11:33 PM  Brain Disorders

Lou Pagnucco said at January 14, 2009 7:25 AM:

A very interesting subject.

I think the evidence is pretty conclusive that "functional and structural brain" physiology/chemistry accounts for every psychological trait, whether "normal" or "pathological". Proposing treatment for "pathologies" sure takes us onto a very slippery slope, unless the treatment is voluntary, perhaps.

The phrase "delusions are pathologic beliefs that remain fixed despite clear evidence that they are incorrect" is troubling, though. It seems to me that many social/affinity groups, especially nations, require holding delusional beliefs for membership. History books, major media, schools, political parties, etc., all seem to promote a version of "reality" spun to benefit authority. I'd maintain that many of our most cherished beliefs could be easily debunked by anyone willing to be ostracized or persecuted.

If interpreted too broadly, whole nations may require treatment.

David Govett said at January 14, 2009 1:09 PM:

This explains so much! Especially the brain injuries caused by the wandering magnetic poles of planet earth.

Lou Pagnucco said at January 15, 2009 7:55 AM:

Just saw the following press release -

Social Conformity Starts In The Brain

Excerpt -
"The present study explains why we often automatically adjust our opinion in line with the majority opinion," says Dr. Klucharev. "Our results also show that social conformity is based on mechanisms that comply with reinforcement learning and is reinforced by the neural error-monitoring activity which signals what is probably the most fundamental social mistake - that of being too different from others."

So, maybe, "normalcy" requires certain delusions, and is a Darwinian fitness trait.

Randall Parker said at January 15, 2009 10:57 PM:


I almost wrote a post on that article because I suspect what it reports is close to the truth. But I always hesitate before doing posts related to brain scans because the brain scan research showing relationships to types of thought might be turning up false positives. I do write posts about brain scan research. But I hesitate to do this.

Lou Pagnucco said at January 16, 2009 7:36 AM:


I hope you did not misinterpret my remarks.

Research relating intelligence, personality, criminality, etc., to brain physiology is important and fascinating.
My impression is that many people regard the issue as taboo - right-wingers because it seems to conflict with the notions of "soul", "free will" and "personal responsibility", and left-wingers because it challenges the ideals of egalitarianism and the perfectability of man --- even though political orientation itself correlates with genes and brain physiology.
Ironic, no?

There is no doubt that real mental illnesses, e.g., schizophrenia, exist which correlate with obvious or subtle brain pathologies.

However, I do believe that the word "delusional" has been used to persecute honest, intelligent people by the actually delusional authoritiarians who usually wield the power - ask Giordano Bruno, Galileo, or anyone who publicly challenges rampaging establishment war propaganda. Sad that conformity, too, seems to be biologically based and favored by evolutionary pressures - you know, how the nail that sticks out gets hammered down.

My observation is that being a "good citizen" means subscribing to the many falsehoods presented in the news and history school texts in any nation, i.e., being "delusional" -- the same kind of pressures appear in most cohesive social groups.

Psychiatrists willing to do the bidding of governments are plentiful.
Laws are surfacing all around the globe that punish "bad attitude" and various "thought crimes".
"Authority always wins" - Mellencamp

But, do not shy away from this topic.

Nerissa Belcher said at January 19, 2009 3:31 AM:

In the article it states that when we interact with groups and differ from them we generate a prediction error. Which is clarified as follows: "A prediction error, first identified in reinforcement learning models, is a difference between expected and obtained outcomes that is thought to signal the need for a behavioral adjustment." The article indicates this causes people to adjust their thinking to conform to the majority. However, another option is to find a group that is more supportive of us. Consider a gay male who moves to a new city and is surrounded by straights. The article implies the gay male would be influenced to become straight. Yet what is more likely to happen is the gay male will find a gay friendly part of the city to move to.

Randall Parker said at January 19, 2009 5:39 PM:


People can change their beliefs more easily than they can change their desires. Some desires are deeply innate. Sexual desire is definitely very innate. People are going to only change to fit in when they can easily do so.

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