Reduplicative Paramnesia: Is This a Symptom of Alzheimer's?

A 70-year-old woman believed that 2 identical houses were located at the same address. She maintained that both homes have the same furniture. Once a doctor examined her, a tumor was found on the right side of her brain. But after the cancer was removed, she realized that she was wrong. There was indeed only one house with one set of furniture, not 2.1

For another woman, the story goes a bit differently:
She is an 80-year-old woman with dementia. Her dementia affects the frontal and temporal parts of her brain. The frontal part of the brain helps with voluntary movement, speech, and cognitive skills. The temporal region stores long-term memory and preserves awareness. The 80-year-old believed that she was not at her house. She maintained that her husband changed her home when she was outside.1

Do you notice a common theme?

Both women's brains duplicated their homes at a single location. Their brains were telling them that there were 2 identical houses in the exact same area. This delusional misidentification of place is known as reduplicative paramnesia (RP).1

What is reduplicative paramnesia?

RP is also known as environmental reduplication.2 People with RP believe with certainty that a place is duplicated, even though it is not. This is a rare disorder. Only 51 cases have been studied since the first report of reduplicative paramnesia in 1903.2

Possible causes of reduplicative paramnesia

A confused or unconscious person's brain can encode certain information about a place but not remember it. When the person becomes conscious, the same area is encoded differently by the brain. Unconsciously, it is an old place. But consciously, it is a new place.1 So the person with RP thinks it is 2 identical places.

Most commonly, people with RP have damage to the frontal and temporal brain regions. It is also caused by damage to the right side of the brain; this area of the brain is responsible for memory and reasoning.

Neurological conditions

Reduplicative paramnesia is mostly seen in people with neurological conditions. It sometimes also occurs in psychiatric patients. People have had reduplicative paramnesia caused by:1-3

  • Stroke
  • Head trauma
  • Psychiatric disorder
  • Organic brain disease, like Alzheimer's or dementia
  • Brain tumor
  • Long-term treatment of depression
  • Brain damage

RP can occur suddenly in those who have had strokes. It can also occur over a long time in Alzheimer's disease.3

The link between Alzheimer's disease and reduplicative paramnesia

RP is so rare that little research has been done on it. One study of Reduplicative paramnesia only examined 4 patients.1 A different study found that RP happens after an acute event. So it is more common with conditions like traumatic brain injury than with Alzheimer's.3

A study found that 25 to 47 percent of Alzheimer's patients had delusional misidentification, the belief that:2

  • Someone close to them is an imposter;
  • They have a double;
  • People around them are able to change their shapes;
  • Several people are really a single person in disguise.

This study also found that RP was associated with Alzheimer’s.2

So RP is a symptom of Alzheimer's?

Sometimes yes, and sometimes no. There is no definite answer or agreement among researchers.

A symptom can be seen in multiple disease states. For instance, cough can be seen in people with the common cold, asthma, lung cancer, and allergies. Reduplicative paramnesia may be a symptom of Alzheimer's, but it can also be a symptom of other problems, like a traumatic brain injury.

More studies and screenings on RP need to be done to better understand the disorder but it is so rare that group studies have not yet been possible.3

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