The Whitworths of Arizona, bringing science to you in everyday language.

Friday, November 4, 2016

Capgras Syndrome, Part 1 of 3

Heard at a support group:

Tom: Donna often thinks I’m “that other man” and keeps asking where Tom went. I’ve tried leaving and coming back. That works better if I change my shirt before I return. Taking her for a ride works, especially if we get a treat. She always knows who I am when she wakes up in the morning, but she’ll ask where I’ve been.

Elmer: Alice keeps wanting to “go home.” I tell her we ARE home, but she can’t seem to accept this. She gets her purse and stands at the door, telling me to “take me home.” Sometimes, I can take her for a ride and “return home” and it works. At other times, she says, “Why did you bring me here, Elmer? This isn’t home.” But she always knows she’s home in the mornings when she wakes up.

Tom and Elmer are both talking about Capgrass Syndrome. Usually this is where the PlwD* believes that someone close to them is a look-alike imposter, as with Donna. It can also be a misidentified place or thing, as with Alice. (In this blog, we are going to talk only about misidentified people, just to keep it simpler, but everything applies to things and places as well.)

What causes people to experience this phenomenon of mistaken identity?

We identify people by comparing them to templates or patterns that we develop in our brains. There are visual templates for what a person looks like, audio templates for what they sound like, and other mental templates for less easy to explain characteristics like emotional connections, beliefs, preferences, behaviors and so on.

As a young woman, I once walked up to a strange man in a parking lot and asked, “Have you seen my husband?” Before I could say more, the man laughed at me and asked, “Who do you think this is?” I had viewed my husband of ten years as a stranger because a barber had removed his beard. He no longer fit my physical template of him, but as soon as he spoke, I blushed. With the additional information, I made the adjustment from “stranger” to “husband.”

But I didn’t have dementia. When a person’s reasoning ability has degenerated enough for Capgras to happen, their brain doesn’t have the elasticity to expand and use new information. It’s like trying to manipulate dried clay. The PlwD may be able to see that the “new” person coming through the door is you, but they will still believe that the “old” person was a look-alike imposter.

My experience with my husband was external. HE had changed, so that he no longer matched my physical template for him. Neither my neural pathways nor my internal templates for him had changed. With Capgras, the change is internal. Donna’s neural pathways between her templates are damaged. Capgras is a neurological dysfunction, like Active Dreams or hallucinations. Donna sees a person who fits her physical template for “Tom.” But if the neural pathways between her visual and mental templates for Tom are broken, Donna will not recognize him as “Tom” but as a look-alike imposter.

Capgras usually occurs only in relation to what a person sees. If Tom talks to Donna on the phone, or even just out of sight, she will recognize him as “Tom.” The connection between her audio template and her mental templates are still functional. Likewise, when she wakes up in the morning, Donna is able to perceive the person lying beside her in bed as “Tom” because pathways between her tactile and mental templates are also functioning.

Ruby: Jason was diagnosed recently with LBD*. We have been married for two years, but now he doesn’t recognize me at all. He asks me when Ruby is coming back, but when I tell him I’m here, he shakes his head. “You are a nice woman and all, but I don’t know who you are,” he tells me. I asked him to help me identify people in a family photo. He named everyone but me. He pointed to me in the photo and said, “I don’t know who that woman is. I wonder why she is in the picture.”

The situation with Jason is different. With Capgras, the physical template is still accessible. The PlwD sees someone who looks familiar even when they don’t recognize that person otherwise. Because Jason’s memory of Ruby appears to be totally erased, he probably has Alzheimer’s in addition to his diagnosed LBD. Alzheimer’s destroys the pathways between a person’s short term memory and their long term memory. Since his “Ruby” memories are much shorter term than his “other family members” memories, the Ruby pathways are less engrained and more easily erased. Unlike Capgras, these pathways do not come and go. They are usually permanently gone.

Why does Donna sometimes recognize Tom and at other times not? With LBD, Capgras tends to fluctuate just as other symptoms do. Like a light switch with damaged wires that connect only part of the time, the pathways function properly some of the time—and sometimes, they don’t. Like other LBD symptoms, the likelihood and severity of Capgras increases with stress and time. Then again, it may leave entirely and be replaced with another symptom.

So what can you do about it? The main thing is to accept it and flow with it. The next two blogs will be about some specific ways to deal Capgras and to help a loved one become better oriented if possible, or to be comfortable and well cared for anyway even if the Capgras persists.

Cornwall G (2014) Questioning Capgras. The Phantom Self, April 30, 2014.

* Acronyms:
LBD: Lewy body dementia
PlwD: person living with dementia
PlwLBD: person living with LBD
DLB: dementia with Lewy bodies
PDD: Parkinson's disease with dementia
MCI: mild cognitive impairment
MCI-LB: the form of MCI that precedes LBD
BPSD: behavioral and psychological symptoms of dementia

For information about Lewy body disorders, read our books:
A Caregivers’ Guide to Lewy Body Dementia
Managing Cognitive Issues in Parkinson's and Lewy Body Dementia

Helen and James Whitworth are not doctors, lawyers or social workers. As informed caregivers, they share the information here for educational purposes only. It should never be used instead of a professional's advice.

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