At 3 a.m., wearing pajamas and socks, an 89-year-old man with Lewy Body Dementia was found by a security guard four floors below his apartment. His walker was later found abandoned on the second floor. Agitated and confused, he insisted repeatedly that he was looking for his “other” apartment. “I know we have two, exactly alike, one that we sleep in at night,” he said. “But I can’t find the other one.”

A 65-year-old woman diagnosed with early-onset Alzheimer’s Disease had what had become a typical spat with her spouse of 40 years. He argued, furious and insulted, “I’m your husband! Don’t you know me?!” “You look exactly like him,” she said quietly, “but I know that you’re not him.” Nothing could convince her otherwise, though the man told her many things only her husband would know. “You are one of the two imposters that come around here, not my husband,” she insisted.

Are these the plots of psycho-thriller movies? Scary stories told around a campfire? Disturbing dreams? No – they are two examples of a neuropsychological condition called Capgras Delusion or Capgras Syndrome, also known as the “Imposter Syndrome” (Hirstein and Ramachandran, 1997).

Capgras Syndrome, named for Joseph Capgras, the French psychiatrist who first described it, also can be seen occasionally in people who are psychotic (typically schizophrenic), or where there has been some type of brain injury or disease (Hirstein and Ramachandran, 1997). Regardless of its source, it can be equally perplexing and upsetting for the person experiencing it as it is for those around him or her to encounter it.

Within psychiatry and psychology, Capgras is considered extremely rare (Ellis and Lewis, 2001, Hirstein and Ramachandran, 1997). There is evidence, however, that it is not as rare as most clinicians believe. It is “uncommon,” but often overlooked (Dohn and Crews, 1986). From my own experience as the director of care for a home care agency, I concur: I see it often enough within my population of people with Alzheimer’s and other related dementias (ADRD) that it is likely not extremely rare.

While Capgras may not be typical, it certainly deserves to be better known both by the general public and among helping professionals. For those of us who love or work with such patients, we need to know how to manage the challenging behaviors that arise from it. Assessment of such patients’ potential danger to others needs to be performed (Silva, Leong, Weinstock, and Boyer, 1989). Awareness of the presence of Capgras also will help caregivers and families know how to better manage their own behavior around and feelings about its symptoms, particularly for the sake of those who are deemed “imposters.”

What Causes Capgras Syndrome?

It’s not known for certain what causes Capgras, but researchers have evolved several credible theories. One is from neurologist V.S. Ramachandran (Ramachandran, 2007). Ramachandran believes that a malfunction between the brain’s visual cortex and the emotional feeling of “familiarity” causes the sufferer to think he or she is seeing a perfect duplicate, not the real thing. The eyes are reporting correctly, but emotions of familiarity aren’t present. The conclusion: here’s an exact imposter.

Ramachandran also reports that a brain injury patient with Capgras was able to correctly identify his mother when he heard her on the phone, but not when he saw her. He hypothesizes that sounds may be correctly connected to the feelings of familiarity in some cases (Ramachandran, 2007).

There are several features particular to Capgras:

  1. The patient has a brain injury or disease.
  2. He or she recognizes that a person or place is exactly like the “real” one, but insists it is not.
  3. The imposter always is a person or place with which the patient is familiar, not a stranger, vague acquaintance, or a new place.
  4. The problem does not fruitfully yield to psychological analysis or interpretation; it is a biological disorder.

Prosopagnosia, a better-known form of facial misidentification, differs from Capgras in that it causes a total inability to recognize previously familiar faces (Ellis and Lewis, 2001). Capgras includes easy recognition of the face, but disagreement about the person’s true identity.

Are Capgras Sufferers Potentially Dangerous?

There are some reported cases where those suffering from Capgras delusion have become dangerous to others, with violent behavior resulting in injury and even death. There is very little research on this subject and not much information with which to reliably predict violence — which is striking given that great hostility and resentment are typical of how sufferers of Capgras view “imposters.”

In a paper by Silva, Leong, Weinstock, and Boyer (1989), they stated that at that time there was little published on the subject of danger and Capgras. A further search in the literature for this article found no papers published later than that date. It should be noted, however, that no cases have been found in the literature of danger paired with dementia; all cases were connected to diagnoses of schizophrenia or bipolar disorder.

Silva, Leong, Weinstock, and Boyer (1989) report several important factors to take into account when assessing danger:

  1. Those “…suffering from multiple coexisting types of delusions of doubles may present with significant dangerous behavior…”
  2. Where there is unabated hostility toward the misidentified person, “… the slightest perceived provocation that the misidentified persons are in some way harming the affected individual may serve as a necessary and sufficient psychosocial stressor that may upset this delicate equilibrium.” Violent behavior could potentially be the outcome.
  3. “…[T]he dangerous behavior… related to the specific delusional content in each case” can be vital. If the delusion points to great danger or evil on the part of the “imposter,” this may increase the potential for violence.
  4. Accessibility to the people involved in the delusion should also be part of the assessment. Is the “imposter” living with the person who holds the delusion, thereby increasing likelihood for opportunity for triggers for violence?
  5. Pre-existing emotional, psychodynamic factors that increase the potential for violence need to be assessed. For example, does the relationship before the delusion between the Capgras sufferer and the misidentified person include high levels of hostility, hatred, or even abuse or assault, thereby increasing the likelihood of future violence?

Violence aside, managing the day-to-day difficult behaviors and emotions around Capgras and dementia takes some specific skills. These will be discussed in Part 2 of this article.