Identified about a century ago, delusional misidentification syndrome is a generic term for a group of delusional disorders.
- Delirium: what it is and what types of delusions
All delusional misidentification syndromes include the belief that something – an object, person or place – has been altered in any way.
In other conditions that involve delusions, such as schizophrenia , a large piece of perception of the patient’s external world has changed. With the delusions of delusional misidentifications , however, it is only one particular object that becomes the focus of delusions. Thus, delusional misidentification syndrome or delusional misidentification syndrome is referred to as a monothematic illusion.
One of the first symptoms of delusional misidentifications to be documented was Capgras syndrome . In this strange condition, a patient recognizes a family member, but at the same time, believes that there is something distinctly unknown about him. This may lead you to conclude that the family member is, in fact, an imposter.
Another syndrome of delusional misidentification , the Fregoli delusion, Fregoli delusion or Fregoli syndrome , is the belief that strangers are really members of the family in disguise. This syndrome can also involve pets or places.
Despite being well documented, the neural basis of these delusions proved to be elusive. Neuroscientists at the Beth Israel Deaconess Medical Center (BIDMC) in Boston, USA, recently strove to dig a little deeper and began to understand which regions of the brain are failing.
Investigating the delusional brain
“The injuries that cause all kinds of delusions were linked to regions of violation of beliefs, suggesting that these regions are involved in monitoring delusional beliefs in general. However, only injuries that caused misleading identification errors were linked to regions of familiarity, explaining the specific bizarre content. Familiarity – in these illusions, that is, injuries had to be linked to both regions to develop delusions like Capgras ”. – Dr. R. Ryan Darby
The study authors are quick to note the research flaws. For example, this mapping methodology does not involve brain imaging, such as functional magnetic resonance imaging (fMRI). It is based on taking data from normal patients and determining regions of the brain that are normally linked to known lesions in the patient’s brain.
Dr. Darby notes that the study would need to be replicated with a much larger sample. This condition is rare, however, and recruitment would therefore be a challenge.
Despite the gaps, the results will still be useful in helping families to deal with this strange phenomenon. Illusions can sometimes disappear as quickly as they arrived, making dealing with the condition very difficult for loved ones.
Dr. Darby says: “The impact on the patient’s family can be painful. I saw patients who, thinking their homes were replicas, packed their bags every night, hoping to return to their “real” home. Thinking that a spouse is an imposter often causes a loss of intimacy. In such cases, even just knowing that the illusion has a name and is part of a neurological disorder can be useful for family members.
The study marks a leap forward in the understanding of delusional misidentification syndromes . As Dr. Fox says: “Understanding where these symptoms come from is an important step in treating them.”