Intermetamorphosis in a Patient With Alzheimer's Disease

SIR: Intermetamorphosis is a misidentification syndrome in which familiar persons are believed to have exchanged identities.¹ We report a patient with clinically probable Alzheimer's disease who developed intermetamorphosis for several members of his family. Analysis of this patient's disturbance suggests abnormal processing between the normal face recognition units and the person identity node in the inferior temporal lobe.^2–4

Case Report

A 76-year-old right-handed man had a 3-year history of progressive decline in memory and cognition. His medical history was remarkable only for prior ethanol abuse. The patient had undergone an evaluation for dementia, including neurological examination, laboratory tests, and neuroimaging. Magnetic resonance imaging was significant only for prominence of the temporal horns of the lateral ventricles, suggesting bilateral mesial temporal atrophy, and he was diagnosed with clinically probable Alzheimer's disease.

About 2 years into his illness he began misidentifying family members. Initially, he misidentified his wife as his deceased mother and, later, as his living sister. His substitution of his sister for his wife became firmly established and could not be corrected with explanation. When confronted, he subsequently claimed that he had never been married or that his wife had left him. Gradually, the patient began misidentifying his son as his brother, his daughter as another sister, and his granddaughter as his daughter. These misidentifications persisted even on the telephone. Moreover, on different clinic visits he described the hospital as a meeting hall or a church where he visited to socialize or to help out.

On examination he was cooperative, attentive, and euthymic. His Mini-Mental State Examination Score was 16 (out of 30), and his examination showed deficits in verbal fluency, confrontation naming, delayed recall, complex constructions, and abstractions. The elementary neurological examination was otherwise normal.

We tested the patient with photographs of familiar persons from a photo album. Positive responses were counted when the photo subjects were positively identified or named. The control was his wife, who scored 100% correct answers. The results showed 100% misidentification of his wife as his sister in photographs with 100% persistence of the misidentification over the past without a retrograde gradient, and correct identification of himself through different ages. He did not have prosopagnosia (he recognized 80% of the photographs) and could recognize his own face in a mirror.

Comment

We present a rarely described intermetamorphosis syndrome occurring in a patient with Alzheimer's disease. The patient did not have facial recognition difficulty, a temporal memory gradient for recalling familiar faces, or a failure to integrate prior memories of familiar faces with currently perceived faces. The misidentifications were not limited to the visual modality, as they occurred with the persons' voices as well. This points to a preservation of the abnormal “person identity nodes” across time and across modalities.

These findings, as well as the reduplicative misidentification of the hospital, suggest an inability to correctly identify the source of his sense of familiarity for family members as a result of temporal lobe disease. Frontal lobe dysfunction also may contribute to his misattribution of identity.⁵