Mirrored-self misidentification is the delusional belief that one's reflection in the mirror is another person – typically a younger or second version of one's self, a stranger, or a relative.
[3] It is caused by right hemisphere cranial dysfunction that results from traumatic brain injury, stroke, or general neurological illness.
[5] Delusional misidentification syndromes (DMS) can occur in patients with a wide variety of cranial dysfunctions.
[3] Mirrored-self misidentification, a type of DMS, occurs most typically in patients with dementia, especially Alzheimer's disease.
[3] Furthermore, a standard neurological or neuropsychological workup tends to overlook the existence of this delusion because affected patients have extensive cognitive degeneration that is the main focus of medical attention.
[1] Injury to the right frontal lobe is found in 35% of cases and can also inhibit one's ability to reject delusional beliefs on the basis of implausibility.
[3] When such extensive neurological damage occurs, the affected patient relies on non-facial cues to identify relatives.
He displayed poor visual memory and visuoconstructional problems but still had basic visuoperceptual skills, a normal intelligence, typical vocabulary, and average semantic ability.
Patient FE was also in early stages of dementia but experienced impaired facial processing rather than mirror agnosia.
He had poor visual memory and visuoconstructional problems whilst retaining basic visuoperceptual skills.
[1] Damage to the right hemisphere, specifically the right dorsolateral prefrontal cortex, impairs the patient's belief evaluation system.
The patient loses the ability to use logic to reject the delusional belief that the mirrored reflection is another person.
[9] When the right hemisphere is damaged in any way, the patient will most likely lose the ability to recognize one's face - the most common feature of self-recognition.
[9] When paired with mirror agnosia or impaired facial processing, damage in any of these areas of the right hemisphere of the brain can lead to difficulties in self-recognition.
[16] This delusion is usually researched through conducting clinical case studies or inducing a state of hypnosis within healthy participants.
[17] While this research method is helpful to understand typical characteristics of the delusion, it can be particularly difficult to conduct a valid study in this way due to patients’ medical comorbidities and general extensive cognitive deterioration.
[5] It is difficult to attribute particular symptoms to the mirrored-self misidentification delusion rather than to a separate feature of the patient's general dementia.
[2] Researchers can remove confusion caused by other unrelated symptoms and make specific conclusions about mirrored-self misidentification itself.
Hypnosis generates false beliefs and disrupts normal cognitive evaluation without having any lasting consequences for healthy research participants.
[19] Cognitive-delusory hypnosis is the most difficult type of hypnotic suggestion to enter and is required to study mirrored-self misidentification.
[3] Comorbidities can be hard to record because the typical patient has Alzheimer's disease[2] or other forms of dementia that make it difficult to separate various existing conditions.