Dementia is a clinical syndrome commonly encountered in clinical practice. Early onset cognitive impairment is always of particular concern and warrants further workup for diagnostic clarity, potentially reversible causes, and prognosis. Unfortunately, although there is increasing knowledge of certain patterns of early onset neurodegenerative disorders, such as early onset Alzheimer’s disease and frontotemporal dementia, more atypical cases exist that do not fit these molds. Here, the case is presented of a 67-year-old man who first developed cognitive impairment at age 47 years. He also had a history of hyperlipidemia, hypogonadism, Lyme disease, anxiety, and attention-deficit disorder. He developed executive function deficits, impaired concentration, apathy, and gait disturbance, which led to loss of job, reduction in household responsibilities, and social isolation. He underwent extensive neuropsychiatric workup and several treatment attempts (for Lyme disease and attention-deficit disorder) over the subsequent 20 years; however, he had progressive indolent neurocognitive decline. This workup ruled out known causes of neurodegeneration but was consistent with early onset atypical parkinsonism with dementia of unspecified etiology. This case demonstrates the course of an early onset dementia that, despite exhaustive medical workup, remains diagnostically unclear. This scenario is common across medical specialties, although not often written about. This article synthesizes the individual approaches of neurologists, psychiatrists, radiologists, infectious disease specialists, and psychologists when presented with the same case and the effective multidisciplinary integration of these efforts even when the exact diagnosis remains unknown.© Copyright 2020 Physicians Postgraduate Press, Inc.