Neurosyphilis can mimic many neurological and psychiatric disorders. Though several of its varied central nervous system manifestations can be measured clinically and by neuroimaging, they are non-specific. Thus, this mimicry and the relative rarity of the illness in the present era make the diagnosis elusive. However, neurosyphilis is readily treatable; therefore, it must be considered a diagnostic possibility in the routine workup of early-onset dementia. This case report is of a young man presenting with psychosis and cognitive impairment. His brain scan showed hippocampal atrophy, a finding not often seen in neurosyphilis but more common in Alzheimer’s disease. Without awareness of the various causes of mesiotemporal atrophy, clinicians may erroneously diagnose cases such as this one as a neurodegenerative disorder.