Notes on Alzheimer's and Capgras

capgras.syndrome.after.Ellis.01

What causes it?

"Capgras is the most common type of delusion..." : But to put it in perspective, it is less common than the popular delusion that a rising stock market will never reverse it's direction (smile).

"Note 1.." Capgras, at least in people with Alzheimer's, appears to be caused by greater activity of the brain chemical dopamine relative to the activity of the brain chemical acetycholine. There is more about the surprising complexity of both neurotransmitters here and here (Wikipedia). There is more specifically about the role of dopamine in Capgras here (Neurology textbook), here, and here (journal articles).



Anomalies

"...there appear to be more pathways involved than those that have to do with reacting to the sight of a loved one." This is an example (source) :
Ellis.2007.fig.3.revised.face.processing


What the delusion can teach us about the undeluded mind

"More...":

Ramachandran assures us that "... far from being a medical curiosity, Capgras syndrome may help us to explore the formation of new memories caught in flagrante delicto" (source) , and "the Capgras delusion... provides clues to understanding the link between visual perception and emotion..." (source) .

According to neurologist HD Ellis, exploring "the structures underlying delusion" have the potential to teach us a great deal about 'beliefs in general'
Brain.lobes.fromcommons



There is a method to the madness

"More detail...":


To state the 'method' in the mind of a Capgras sufferer more technically: "...Negative effects of right hemisphere injury impair self-monitoring, ego boundaries, and attaching emotional valence and familiarity to stimuli. The unchecked left hemisphere unleashes a creative narrator from the monitoring of self, memory, and reality by the frontal and right hemisphere areas, leading to excessive and false explanations. Further, the left hemisphere's cognitive style of categorization, often into dual categories, leads it to invent a duplicate or impostor to resolve conflicting information. Delusions result from right hemisphere lesions. But it is the left hemisphere that is deluded...." from "Delusional misidentifications and duplications: right brain lesions, left brain delusions"


Elsewhere,
"...What I have argued throughout is that the impostor belief, although formed as a result of some form of cognitive disruption, actually (re)structures the experience, making belief and experience congruent. The experience validates the belief, and the experience is believed to be authentic..." and "...the delusional belief constitutes an attempt on the part of the patient to explain his/her initially odd and somewhat disturbed [experience of the loved one] (which I refer to as a sense of estrangement) and, moreover, that the delusion then structures the patient's experience such that what he/she perceives is an impostor..." from Capgras delusion: An interactionist model.

 
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