Very early onset dementias: Importance of differentiating from schizophrenia spectrum disorders

Very early onset dementias and other neurodegenerative diseases often present with prominent behavioral disturbances and can be initially misdiagnosed as schizophrenia spectrum disorders. Differentiating a primary psychiatric condition from a neurodegenerative cause is important, because there are considerable differences in prognosis, treatment, and the services required for effective management. To illustrate the implications of misdiagnosis, we provide case examples of very early onset dementias, most of which were initially diagnosed as schizophrenia or other psychotic disorder, owing to their unusually young age of onset and initial behavioral presentations. We suggest how a clinician can differentiate schizophrenia from rarer, early onset neurodegenerative causes of altered behavior and mentation, including behavioral variant frontotemporal dementia (bvFTD), Wilson's disease, adult metachromatic leukodystrophy (MLD), Creuzfeldt-Jakob disease (CJD), and very early-onset Alzheimer's disease. Schizophrenia with prominent obsessive-compulsive (OC) symptoms is briefly discussed, given that OC symptoms can be a major feature of dementias with prominent behavioral components.