For today’s blog, I want to dive deeper into Capgras syndrome: why we think it happens and what to do about it. Some people living with dementia develop Capgras syndrome–which is a fixed, false belief that family members are being replaced by look-alikes…by imposters.
My First Encounter with Capgras Syndrome
When I first started working as a nurse practitioner in the Memory Clinic almost 8 years ago, I was hired as the “care-refusal” expert because of my knowledge and research in that area of dementia behaviors. At the time, I was running my own federally-funded study, which involved testing methods for getting people with dementia (who lived in nursing homes) to accept mouth care. When one of the physicians referred a patient to me who was refusing to allow her husband to help her with bathing and dressing, I did not think anything of it. I was so wrong! Turns out, the woman living with dementia was refusing to allow her husband to help her with her care because…he WAS NOT HER HUSBAND! She proceeded to tell me that her “real” husband had been replaced by an “imposter.” She also shared that there were several imposters representing her husband. As I listened to her story in the clinic, I was both fascinated and overwhelmed. I had never encountered this situation in all of the years I provided care to people living with dementia in nursing homes!
Luckily, one of the senior neurologists was available. I described the scenario to him, and he immediately told me that my patient was likely experiencing “Capgras syndrome.” He quickly pulled up some references to the syndrome from the PubMed database. The available information was anemic and contradictory. The publications were predominantly case studies and it seemed that every author had his or her own theory about the cause. The treatment was pharmacologic: prescribe some antipsychotic medication and hope the behavior goes away. I returned to the room and explained what was going on: “Your wife is experiencing something called a delusion, a fixed false belief. Her specific delusion is known as Capgras syndrome. We are not sure why this happens, but people with dementia believe that family members are replaced by doubles. I’d like to try some quetiapine, 25 mg twice a day.” When I checked back a week later, the quetiapine was helping. She still was not convinced that her husband was “the real one,” but she was allowing him to help her with her care.
The Historical Origins of Capgras Syndrome
In 1923, Joseph Capgras, a French psychiatrist, described the unique behavior of his patient, known only as “M” in the historical records. By her 53rd birthday, she had suffered the loss of three children, including twin sons. Soon after these losses, “M” Although became convinced that her husband and remaining children were duplicates. Prior to these delusions, “M” had had no psychiatric problems (or at least, none that she admitted to having). Capgras named this behavior “illusion of doubles.” Capgras syndrome is part of a larger group of delusional behaviors known as “Delusional Misidentification Syndrome.”
How Common is Capgras Syndrome in Dementia?
Capgras syndrome can affect anyone with dementia, but it seems to be most common in Lewy Body Dementia. One study found that 68% of the patients with Capgras syndrome had Lewy Body dementia, compared to 18% with a probable Alzheimer’s diagnosis. Across the dementias, Capgras syndrome is reported to affect 17-28% of people with Lewy Body dementia and 16% of people living with Alzheimer’s dementia. Capgras syndrome can affect people with Parkinson’s disease dementia, but the numbers reported in the literature are very low.
Capgras syndrome is more likely to occur in people in the moderate to severe stage of dementia and in people already experiencing visual hallucinations. This article does a nice job of describing the characteristics of people living with dementia who may be affected.
What Causes Capgras Syndrome in Dementia?
The current theory involves a “breakdown” between multiple parts of the brain responsible for recognizing faces and linking emotions to those faces. Before I go too deep, here is a quick and dirty neurobiology lesson. The temporal lobes (which sit behind the temples and a little above the ears) are predominantly involved with understanding and interpreting language, but are also important for understanding sights—understanding what you see. The occipital lobes (located at the back of the head) is very important for vision—for taking the messages from the eyes and translating the messages into shapes and pictures. The temporal and occipital lobes work together to help recognize visual images. Scientists believe that specific areas in both of these lobes work together to recognize faces: the inferior occipital gyrus, the lateral occipitotemporal gyrus, and the superior temporal sulcus.
One a face is recognized, other parts of the brain are recruited to retrieve and analyze emotional information about that face. These parts that hold the emotion are known as the limbic system and include the amygdala and the hippocampus. Let me give you an example. A couple of weeks ago, I attended my son’s and his fiancé’s wedding shower. When I saw my son, my brain simultaneously recognized his face, pulled up emotions such as “love” and “pride”, and then analyzed those emotions and concluded that I love him and I’m proud of his accomplishments…including convincing a lovely woman to put up with his shit and marry him. This process happened in nanoseconds.
In a healthy brain, messages are sent from one part of the brain to other parts of the brain by networks, or highways, made up of millions of neurons who pass messages up and down the networks—almost like runners in a relay race passing the baton to each other. As these neurons die off, the networks, or highways, become unreliable and messages do not get consistently passed from the limbic system to the temporal lobes. In the dementia-damaged brain, two things are happening simultaneously. Parts of the temporal lobe and occipital lobe are experiencing loss of neurons AND the connections between the limbic system and the temporal lobes are eroding away. The end result is a weird situation where the person living with dementia recognizes the face but does not experience the emotional connection to that face. They realize that something is “off”, that the emotional connection is missing. The dementia brain jumps to its own version of logic and believes that the “real” person is gone and has been replaced with a look-alike imposter. As more of the temporal and occipital lobes shrink, even the ability to recognize faces becomes more impaired and the person living with dementia may soon believe that there are 3, 4, or even 10 “imposters” for the one “real” spouse or other close family member.
Capgras only seems to impact “close” family members. This is likely due to the high emotional connections associated with these family members.
What Can You Do If Your Family Member Has Capgras Syndrome?
This is really tricky. Arguing with the person living with dementia is pointless. Sometimes family members will admit they are imposters in an attempt to “go along” with the person living with dementia—which makes sense, because arguing does not work. However, this approach bites them in the butt—the person living with dementia may remember that the family member admitted that they were imposters, and this admission only strengthens the delusion.
Some approaches that may work include calling out to the person living with dementia before appearing in front of them. It is possible that their brain successfully links the sound of your voice to positive emotions, so that when you step in front of them the emotional connection is still there—still linked to the sound of your voice, if not to the recognition of your face. Another approach is to emphasize the positive aspect of your presence: “I’m here to help you. I’m here to make sure you are safe.”
All of the articles I read as I prepared this blog listed second generation antipsychotics—specifically, quetiapine—as helpful in decreasing, even stopping, Capgras syndrome. One article that I read suggested lowering levodopa dosages. Apparently, 2 people with Parkinson’s disease developed Capgras syndrome and the syndrome resolved by lowering their dosages of levodopa and giving them quetiapine. Please don’t mess with your loved ones’ medications—please consult their provider before doing anything.
Capgras syndrome is a poorly understood phenomenon that occurs across the dementias but seems to be more prevalent in Lewy Body dementia. Many clinicians and researchers continue to describe it as a psychiatric illness, a description that I find decidedly unhelpful. For those of you struggling with this behavior, I hope this blog post shed some light onto this problem and helped you feel a little less alone.
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Dr. Rita Jablonski
Rita Jablonski, PhD, CRNP, FAAN, FGSA is a nurse practitioner, researcher, tenured professor, and former family caregiver. Her research and practice involve all aspects of dementia management; she is best known for non-drug strategies to address dementia-related behaviors.