Neuroimaging Biomarkers in a Patient With Probable Psychiatric-Onset Prodromal Dementia With Lewy Bodies.

Objectives: Psychiatric-onset prodromal dementia with Lewy bodies (DLBs) is a recently proposed clinical entity characterized by psychiatric presentation that may predate clinical dementia by many years. It is not yet clear how to identify patients with prominent late-onset psychiatric symptoms who may have underlying Lewy body disease. In this article, we describe how neuroimaging can assist in the identification of this condition.

Methods: A 77-year-old man presented with late-onset psychosis. He underwent an extensive clinical and neuropsychological evaluation. These included brain MRI with arterial spin labeling (ASL) which quantifies perfusion. FP-CIT SPECT and I-metaiodobenzylguanidine scintigraphy assessed striatal dopaminergic and cardiac adrenergic integrity, respectively.

Results: Clinical evaluation revealed a history of REM sleep behavior disorder and parkinsonism induced by antipsychotics. The patient's cognitive function was normal. Conventional MRI showed parieto-occipital atrophy, and posterior hypoperfusion was revealed by ASL-MRI. Of note, the "cingulate island sign" was present. FP-CIT SPECT and I-metaiodobenzylguanidine endorsed the suspicion of α-synucleinopathy. The patient fulfils the recently proposed key features of psychiatric-onset prodromal DLB.

Discussion: Prodromal DLB is an emerging concept. Biomarkers have not been yet established. We propose that nuclear imaging and advanced MRI technics showing posterior hypoperfusion and the presence of the "cingulate island sign" could be promising biomarker candidates.