Capgras Syndrome in Lewy Body Dementia

Does your loved one with Lewy body dementia accuse you of being an imposter? They may have Capgras syndrome—a disorder that is also known as Capgras delusions, delusional misidentification syndrome, and the "delusion of doubles." 

The Lewy Body Dementia Association describes Capgras syndrome as a "temporary but sometimes repeated belief that a caregiver, family member, or location has been replaced by an identical imposter." The most common subject of Capgras syndrome is the spouse or significant other. 

Experts estimate that up to 17% of people with dementia with Lewy bodies experience Capgras syndrome.

Hallucinations and Capgras Syndrome

Research indicates that hallucinations in Lewy body dementia are highly correlated with the development of Capgras syndrome. One study also found that people who were being treated with cholinesterase inhibitors (which are sometimes used to treat hallucinations in Lewy body dementia) were less likely to develop Capgras syndrome.

Anxiety and Capgras Syndrome

Anxiety has also been identified as a significant risk factor, with one study finding that people with anxiety and dementia with Lewy bodies had 10 times the risk of developing Capgras syndrome.

Prevalence of Capgras Syndrome in Alzheimer's

Research has concluded that some people with Alzheimer's disease also develop Capgras syndrome, although some studies indicate they may also have some Lewy bodies in their brains.

Other Conditions Associated With Capgras Syndrome

Capgras syndrome has been described in other degenerative brain diseases, including Parkinson's disease (which is very closely related to Lewy body dementia) and frontotemporal dementia. It has also been found in people with schizophrenia, strokes, and drug abuse.

How to Respond

Caregivers of people with Capgras syndrome report increased challenges compared to caregivers of people with Lewy body dementia who do not display Capgras syndrome.

Because the cognitive function of people with Lewy body dementia varies greatly from time to time, responding to Capgras syndrome is difficult. Sometimes, just going with the flow of the conversation will work, but some caregivers report that the person with Lewy body dementia will catch them in verbal inconsistencies if, for example, they agree that they're the imposter.

Additionally, since the person may believe the caregiver or family member is an imposter, verbal or physical aggression is possible, so caution is suggested in response to Capgras syndrome.

You may find that some of the same tips on responding to hallucinations in Lewy body dementia work well in Capgras syndrome since both hallucinations and Capgras syndrome are a misperception of reality.

Since arguing with someone with dementia is rarely effective, you can try pointing out to them that even if you're not the "real" person, you're still there to help them. You can also try using distraction with music, a favorite TV show or the latest news about a sports team. 

One other strategy to try is to leave the room, wait a few minutes, and then greet your loved one verbally before you enter the room. Depending on the location and extent of the damage to their brain, it's possible that they could recognize and be reassured by your voice before they see you.

Treatment

Treating Capgras syndrome requires a cautious approach if medications are going to be used. People with Lewy body dementia are more at risk for serious side effects from antipsychotic medications, which are often prescribed for paranoia, delusions, and hallucinations. Be sure to report Capgras syndrome to your loved one's physician for proper evaluation and treatment.

A Word From Verywell

Capgras syndrome presents an additional challenge for those experiencing Lewy body dementia, as well as their caregivers. Despite the frustrations that it creates, try to remember that Capgras syndrome can be very anxiety-producing for the person with dementia. Responding calmly and compassionately after taking a deep breath can help you both.