Skin Biopsy Diagnosis of Late-Onset Psychosis as Prodromal Dementia With Lewy Bodies: A Case Series

What is it about?

When severe psychiatric symptoms such as psychosis begin late in life, this may be due to atypically late onset of a primary psychiatric disease such as schizophrenia, or may be secondary to an “organic” etiology such as a neurodegenerative disease that will progress to dementia. Longitudinal studies that follow patients with late-onset psychosis over many years indicate that about half develop dementia. Currently, there is no reliable way to distinguish psychiatric-onset neurodegenerative disease from primary psychiatric conditions based solely on presenting symptoms. Accurate diagnosis is essential, especially to identify prodromal Dementia with Lewy Bodies (DLB), a synucleinopathy commonly presenting initially with isolated psychiatric features, as neuroleptic treatment can be harmful or fatal in overt DLB. We have therefore begun using a new clinically-approved skin biopsy test for synucleinopathy in the evaluation of patients hospitalized for late-onset severe psychiatric symptoms in whom there is clinical suspicion for a neurodegenerative process. We describe the clinical features and course of five consecutive psychiatric inpatients (four with psychosis) tested over three months. Two psychotic patients tested positive; both initially had isolated psychiatric symptoms, developing parkinsonism only after neuroleptic exposure. To our knowledge, this is the first biomarker-confirmed diagnosis of psychiatric-onset prodromal DLB, found in two of four patients with late-onset psychosis. Although these findings from a small clinical series require replication and systematic investigation, we believe they are important to disseminate among psychiatrists, neurologists, and neuropsychiatrists as they suggest a potentially high prevalence of DLB underlying late-onset psychosis and highlight clinically-available diagnostic tests.

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