Neuropsychiatric Diagnostic and Treatment Conundrums: Case Study of an Inpatient With a Complex Illness Presenting With Overlapping Features of Frontotemporal and Lewy Body Dementia.

Frontotemporal dementia (FTD) and Lewy body dementia (LBD) are distinct neurodegenerative disorders that rarely co-occur. However, their overlapping features can obscure diagnosis and complicate management. We present the case of a 65-year-old man with a history of alcohol use disorder, diabetes, and blindness who developed acute behavioral changes, catatonia, and fluctuating mental status. He exhibited signs consistent with a behavioral variant FTD, including disinhibition, executive dysfunction, and hypersexuality, as well as features associated with LBD, including visual hallucinations, autonomic instability, and waxing-and-waning impairment in cognition. His hospital course was marked by episodic disorientation, variable language use, and persecutory delusions. Neuroimaging, cerebrospinal fluid analysis, and serial neuropsychological testing yielded mixed and inconclusive results, contributing to the diagnostic ambiguity. Treatment included lorazepam, which improved catatonic symptoms but was discontinued due to risk of delirium, and aripiprazole, which was tapered due to suspected neuroleptic sensitivity. The patient was ultimately discharged to memory care with a diagnosis of an unspecified dementia. This case underscores the challenges of diagnosing and managing patients with overlapping features of multiple neurodegenerative disorders. Recognizing points of overlap between syndromes like FTD and LBD is key to tailoring interventions and avoiding harm. Serial cognitive assessments, functional neuroimaging, and biomarker analysis may improve diagnostic accuracy, although these tools have limitations. A deeper understanding of the pathophysiology of overlapping dementia syndromes is crucial for improving diagnostic clarity and guiding treatment strategies.