Frontotemporal dementia presenting as schizophrenia-like psychosis in young people: clinicopathological series and review of cases.

BACKGROUND: Few studies have investigated the relationship between schizophrenia and frontotemporal dementia. AIMS: To investigate this relationship through a clinicopathological investigation of young-onset frontotemporal dementia and a review of the case literature.
METHOD: Cases of young-onset frontotemporal dementia were identified within the local brain bank. The clinical course and pathological findings were collated. For the literature review, cases of frontotemporal dementia identified through Medline were selected according to defined criteria. The demographic, clinical, pathological and genetic characteristics of cases presenting with a psychotic illness were identified.
RESULTS: In the case series, 5 of 17 patients with frontotemporal dementia had presented with a psychotic illness (schizophrenia/schizoaffective disorder n=4, bipolar disorder n=1) an average of 5 years prior to the dementia diagnosis. Patients with schizophrenia exhibited changes consistent with TDP-43 and ubiquitin-positive frontotemporal dementia. In the cases review, a third of patients aged 30 years or under and a quarter of those aged 40 years or under had been diagnosed with psychosis at presentation.
CONCLUSIONS: Patients with young-onset frontotemporal dementia may be diagnosed with a psychotic illness years before the dementia diagnosis is made. These findings have implications for clinicians and for our further understanding of the neurobiology of psychotic illness.