Capgras Syndrome as an Initial Manifestation in a Patient With Neurosyphilis

The patient was a 52-year-old woman who had no prior psychiatric history or head injuries. Two months prior to hospital admission, she developed delusions that her family members were dead and had been replaced by others pretending to be her family; this was identified as Capgras syndrome. She presented with an irritable mood and violent behaviors toward her family. She was admitted to our acute psychiatric ward. Laboratory work, including a complete blood count, a basic chemistry panel, tests of thyroid function and levels of folate and vitamin B12, and an autoimmune survey, was within normal limits. The EEG showed a diffuse background, slowing at 6–7 Hz. Cerebral MRI data revealed mild subcortical atherosclerotic encephalopathy. The patient was tentatively diagnosed with late-onset schizophrenia and treated with risperidone 6 mg/day. Her psychiatric symptoms improved, and she was discharged 50 days after admission. Capgras syndrome was not noted during the outpatient clinic follow-up. However, a rapid decline in memory was noted 6 months after discharge. She was admitted to our neurological ward. Her Mini-Mental State Examination (MMSE) score was 19/30. The patient had no history of skin lesions or focal neurological deficits. The syphilis rapid plasma regain and venereal disease research laboratory serologic tests were positive. The fluorescent treponemal antibody absorption test was positive (4+), and Treponema pallidum particle agglutination was positive with titers > 1:2560. The serum HIV antibody test was negative. A lumbar puncture was performed, and CSF examination revealed lymphocyte-predominant pleocytosis and an elevated total protein concentration (60 mg/dL). The Treponema pallidum hemagglutination assay of the CSF was positive with titers > 1:1280. The resulting diagnosis was neurosyphilis. The patient intravenously received 24 million units of penicillin G per day for 14 days. The patient was discharged after antibiotic treatment and continued to be prescribed risperidone for psychosis.

The psychiatric presentations of neurosyphilis include dementia symptoms, depression or mania, personality changes, hallucinations, and delusions.^2,3 The first symptom of this patient was Capgras syndrome. It has been estimated that 25%−40% of cases with Capgras syndrome are associated with organic disorders, including dementia, head trauma, epilepsy, and cerebrovascular disease.⁴ Based on our research, this is the first report of Capgras syndrome in neurosyphilis. This case emphasizes that neurosyphilis must be considered in the differential diagnosis of subjects with Capgras syndrome.