Syphilis is a sexually transmitted disease caused by Treponema pallidum. Early invasion of the central nervous system might occur early in the course of the disease. Clinical manifestations may include acute meningeal syphilis, meningovascular syphilis, paretic neurosyphilis and tabetic neurosyphilis. Psychiatric symptoms are often the presenting symptoms of this illness and the correct diagnosis involves both a high degree of suspicion and adequate diagnostic tests.

The authors report a case of a patient, with no previous history of mental illness, initially admitted in a psychiatric unit with a clinical picture suggestive of a mixed bipolar disorder episode who has been diagnosed with neurosyphilis a year after.

Review of clinical records and complementary exams.

By the first admission, the patient presented with depressed and irritable mood, emotional lability, aggressiveness, grandiose and racing thoughts. Upon discharge, he was diagnosed with bipolar disorder and referred to ambulatory unit. The following year he starts presenting cognitive deficits and a progressive loss of autonomy in daily living activities, being referred to neurology evaluation. A year after the first admission, he is admitted in a neurology unit and diagnosed with neurosyphilis.

Current prevalence of symptomatic neurosyphilis in Western Europe is unknown. Atypical cases presenting with heterogeneous psychiatric and neurologic symptoms, with no previous history of mental illness, should raise a high index of clinical suspicion, since consequences for the patient's health might be severe if not properly diagnosed and treated.

The authors have not supplied their declaration of competing interest.