Persistent post-concussive syndrome (PPCS) outlines a complex array of neurocognitive and psychological symptoms that persist in patients after a concussion. A 58-year-old female presented reporting recurrent loss of consciousness, and retrograde and anterograde amnesia following multiple concussions. She also endorsed persistent nausea, balance insufficiencies, hearing loss, and cognitive impairment. In addition, this patient had high-risk sexual behavior without prior testing for sexually transmitted infections. Given her clinical history, the differential included PPCS, complex post-traumatic stress disorder, Korsakoff syndrome, hypothyroidism, and sexually transmitted infection (STI)-related neurocognitive disorder. On exam, this patient had a positive Romberg sign, prominent resting tremoring of upper extremities, and pinpoint pupils unresponsive to light, with bilateral nystagmus. Syphilis testing was positive. The patient was treated with intramuscular benzathine penicillin with significant improvement in gait, balance, headaches, vision, and cognition three months after treatment. Although rare, neurocognitive disorders, including late-stage syphilis, should be considered in the differential diagnosis for PPCS.