Objective: Dementia with Lewy bodies (DLB) is the second most common cause of neurodegenerative dementia, after Alzheimer’s disease (AD). While mild cognitive impairment (MCI) is a key prodromal syndrome for AD, the prodrome for DLB is likely more broad with syndromes other than MCI. The purpose of this case report is to highlight a possible non-MCI presentation.

Background: Rapid eye movement sleep behavior disorder (RBD) is strongly associated with neurodegenerative synucleinopathies, like DLB, and can present years prior to the onset of cognitive impairment.

Method: Here, I present a 47 years old man with spontaneous psychosis, RBD, autonomic dysfunction, and fluctuations in level of alertness with no objective cognitive impairment.

Results: At the time of presentation to our center, the patient had been experiencing visual and auditory hallucinations for 5 years in the absence of a mood or other primary psychiatric disorder. He had no prior history of psychosis. He had been experiencing symptoms of RBD (diagnosis confirmed with polysomnogram) for 4 years. He had been evaluated by Psychiatry, Neuroimmunology, Epilepsy, and Memory Care specialists with no clear diagnosis in the setting of an unrevealing, extensive work-up, which included a normal brain MRI, long-term monitoring EEG, paraneoplastic CSF and plasma panels, 24 urine collection for catecholamines and porphobilinogens, CT scans of the chest, abdomen, and pelvis, HIV, ceruloplasmin, and syphilis testing. In addition to hallucinations and RBD, he had been experiencing excessive night-sweats for 5 years and underwent tilt-table testing on one occasion with evidence of increased sympathetic tone in the supine position. Despite self-reports of cognitive impairment, extensive neuropsychological testing failed to detect deficits with normal to high-normal performance across all domains. EMG/NCS was done with no evidence of polyneuropathy, generalized peripheral nerve hyperexcitability, fasciculations, myokymia or neuromyotonia. On exam, there was slight parkinsonism in his right upper extremity. DaTscan was subsequently obtained and demonstrated asymmetrically decreased radiotracer in the left basal ganglia.

Conclusion: I proposed that this case may represent a psychiatric prodrome/pre-dementia subtype of DLB with disproportionate limbic involvement over other areas of the brain.

References: [1] McKeith I, Taylor JP, Thomas A, et al. Revisiting DLB Diagnosis: A consideration of Prodromal DLB and of the Diagnostic Overlap With Alzheimer Disease. Journal of Geriatric Psychiatry and Neurology. 2016; 29(5): 249-253.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-possible-case-of-prodromal-dlb-with-prominent-hallucinations-autonomic-dysfunction-and-rem-behavior-disorder-but-absence-of-cognitive-impairment/