Abstract
BACKGROUND: Delirium-onset prodromal Lewy body disease (LBD) has been proposed as one of the primary phenotypes of prodromal stages of LBD. The detailed clinical features and biomarker profiles of delirium-onset prodromal LBD have not been well characterized. METHODS: Five consecutive cases of delirium-onset prodromal LBD were documented. The diagnosis of prodromal LBD was made based on neuroimaging biomarkers, including dopamine transporter single-photon emission computed tomography (SPECT), cardiac (123)I-metaiodobenzylguanidine scintigraphy, and/or brain perfusion SPECT, as well as clinical findings in the post-delirium follow-up periods. RESULTS: In all cases, one or more of the core or supportive clinical features of dementia with Lewy bodies, including rapid eye movement sleep behavior disorder, minor hallucinations, hyposmia, or autonomic dysfunction, were present prior to the onset of delirium. The precipitating factors for delirium were diverse, including surgery, radiation therapy, chemotherapy, and infection. The duration of delirium was prolonged for several months in two cases, whereas it was resolved within a few weeks in the other cases. In most cases, persistent mild cognitive or behavioral symptoms were observed, which were improved with donepezil. CONCLUSIONS: Our observations suggest that delirium-onset prodromal LBD may represent the later stages of the prodromal LBD rather than its initial stages. It is possible that delirium in the prodromal stages of LBD may represent subthreshold cognitive fluctuations that are transformed into clinically detectable states by a variety of precipitating factors.