SIR: Interictal psychosis in patients with epilepsy is highly correlated with temporal lobe epilepsy.1 Fregoli syndrome is the delusional misidentification of familiar persons disguised as others. While the organic etiology of Capgras syndrome, another delusional misidentification syndrome (DMS), is widely studied, there are only anecdotal reports on a similar etiology for Fregoli syndrome. A case of interictal psychosis presenting with Fregoli syndrome is described and the neurobiological basis of the syndrome is discussed.
A 30-year-old woman was admitted with first break psychosis of acute onset characterized by disorganized behavior, loosening of association, auditory hallucinations, and persecutory delusions. The striking feature of the patient’s psychopathology was her misidentifying strangers as people known to her. In the emergency room, she misidentified another patient as her boyfriend and on the unit she misidentified the nurse as her mother and the social worker as her sister. Though these persons bore no close resemblance with the patient’s family members, the patient was convinced that her family members had been transformed into these strangers.
The patient had no prior psychiatric history and family history was noncontributory. Following a motor vehicle accident 8 years ago, she was being treated with oxcarbazepine (600 mg twice a day) for complex partial seizures with secondary generalization. Last episodes of generalized tonic clonic seizure and complex partial seizure were 2 years and one month ago, respectively. Her neurological examination and laboratory work up was unremarkable. A Mini-Mental State Examination was attempted but the patient’s severe disorganization precluded any meaningful interpretation. While in the hospital, her initial EEG was reported as normal while another one done two weeks later when the psychosis started to remit showed left temporal spike and sharp waves. The MRI of the brain was normal. The patient was treated with risperidone and her oxcarbazepine was increased to 900 mg twice a day. Her psychosis, including the delusions of misidentification, completely resolved within a month and a repeat EEG done before the discharge did not show any epileptiform discharges. Interestingly, the patient had no memory of her misidentifying the staff on the unit.
The notable feature of this presentation was the occurrence of Fregoli syndrome in the setting of epilepsy. EEG abnormalities and epilepsy have been anecdotally reported with Fregoli syndrome.2 Other conditions associated with Fregoli syndrome include stroke, head injury and Alzheimer’s dementia.2,3 One study demonstrated anterior cortical atrophy in psychotic patients with Fregoli syndrome compared to those without this syndrome.4 Although the bulk of literature on DMS implicates a right-sided brain pathology,2 interictal psychosis per se is most commonly associated with a left-sided functional brain abnormality.1
The neurobiological basis of Fregoli syndrome is discussed below. Capgras syndrome, the commonest of the DMS involving "hypo-identification," is understood to result from right temporolimbic-frontal disconnection resulting in a disturbance in familiarity of people and places.3 However, this hypothesis may not explain the Fregoli syndrome, which involves "hyper-identification." Thus alternative hypotheses have been explored and one such hypothesis postulates that interhemispheric disconnection of cortical areas could allow each hemisphere to establish independent images of a person, place or event.3 Hence if one hemisphere cannot explain the perception received by the other hemisphere, the individual deals with this discrepancy by confabulating about the experience. This has been demonstrated by split-brain research when subjects with callosotomy confabulate on presenting with different visual stimuli to either hemisphere.5 Interestingly, some investigators regard DMS as a type of confabulation citing evidence from Korsakoff and Hughlings Jackson.3 In this context, DMS is a disturbance in personal relatedness between the self and environment and Fregoli syndrome entails an insertion of personal relatedness (confabulation) resulting in "overpersonalized misidentification." Finally, frequent seizures may lead to aberrant plastic regeneration of synapses,1 with the resultant "miswiring" leading to a functional disconnection between the cortical areas. That carbamazepine, an antiepileptic that inhibits kindling in temporal lobe, has been helpful in treating individual cases of DMS supports the above notion.6