Fregoli Syndrome: A Rare Delusional Misidentification Syndrome

Abstract

Fregoli syndrome is a rare delusional misidentification syndrome (DMS), in which a patient believes that one or more familiar persons are disguised as different people. That is, although other persons appear in their normal visual form, the patient is convinced that they are someone familiar in disguise. This syndrome was first described by Courbon & Fail in the year 1927. This article mainly reviews the etiology, neurobiology/neuropathology, differential diagnosis, treatment, gaps & limitations in existing literature, recent findings and future directions of research in the aspect of this syndrome. It spans both psychiatric and neurological domains. Available literature suggests that a substantial portion of cases have secondary (organic) causes, especially in older individuals or those with first episodes, and these are often associated with right hemisphere lesions. Cognitive disturbances (memory, executive function) and anomalies in emotional recognition/familiarity are common. Treatment is empirical with antipsychotics. Clinicians should maintain a high index of suspicion for organic contributors, perform thorough diagnostic workups and individualize treatment. Research remains limited, more systematic, standardized and prospective work is needed in this area.