An 87-year-old Mexican man, with advanced dementia who was sometimes combative (threw forks at home), diagnosed with Alzheimer’s Disease for over 20 years, was brought in by his son as a new patient. Apparently other family out-of-state got worn out, arrived unannounced to hand him off, and promptly fled. Medical records were impossible to come by, so I ordered routine lab tests. His syphilis test came out positive.
Did he have late syphilis of the brain all that time (the most common reason for placement in mental asylums in the 19th century)? Impossible to say. It would have required a spinal tap, which would likely have required general anesthesia, and treatment wouldn’t have changed anything. The patient couldn’t be placed in a nursing home since he was uninsured and undocumented (waiting lists at our local public long-term care facility are very long).
The American Academy of Neurology does not recommend syphilis testing for dementia, since the disease is so rare nowadays. But it may be more common than expected among elderly immigrants who’d never received much health care in their poor countries-of-origin. And in up to 25% of patients with late syphilis, the most common test (RPR or VDRL) may be negative, requiring a second level of testing (a treponemal test) for diagnosis (see Syphilis, section on “Tertiary Syphilis”, also Syphilis — Blood Tests.