New-Onset Delusions Heralding an Underlying Neurodegenerative Condition: A Case Report and Review of the Literature.

To present a striking case of new-onset psychosis in a middle-aged woman subsequently diagnosed with behavioral variant frontotemporal dementia (bvFTD). To review the data regarding key red-flag features that may suggest a diagnosis of a neurodegenerative process, and specifically bvFTD, rather than a primary psychotic disorder. To examine the role of genetics, especially mutations of the microtubule-associated protein tau (MAPT) gene, in familial cases of frontotemporal dementia (FTD).The pertinent literature was searched online (PubMed, Google Scholar) using the following search terms: frontotemporal dementia (FTD), Pick's disease, behavioral variant FTD (bvFTD), psychosis, delusions, MAPT, and genetics. No date or language limit was applied.The case report was generated through detailed assessment of clinical notes, imaging studies, and laboratory results. The brain autopsy was carried out and summarized by our neuropathology team. Previously published literature was selected for inclusion in the review section based on relevance to the topic.A neurodegenerative etiology for psychosis (and specifically bvFTD) should be suspected in patients with progressive deficits in executive function, language, or memory. Other key warning features include the presence of a strong family history of a late-life psychotic disorder (or institutional placement or suicide), loss of empathy, impaired recognition of facial expression, or the development of emotional blunting and apathy, abnormal movements, or seizures.Neurodegenerative disease should be on the differential diagnosis for any patient presenting with new-onset psychosis and behavioral changes in mid to late adulthood. Should red-flag features be present, early referral to a clinic specializing in dementia is recommended for further evaluation. This case highlights that MAPT mutations can be associated with psychosis in FTD and should be considered in the genetic workup. Ongoing research into the cellular and neural circuit mechanisms of psychosis in neurodegenerative disease may shed light on pathologic processes underlying psychosis in primary psychiatric disorders.