Is Neurosyphilis the Cause Behind Cognitive Impairment in Individuals with HIV?

Neurosyphilis was not associated with cognitive impairment in individuals with HIV and previous syphilis, according to the findings of a new study.

The researchers examined data from 132 HIV-infected participants involved in a study of cerebral spinal fluid (CSF) abnormalities in syphilis who underwent a mental alternation test (MAT), venipuncture, and lumbar puncture. Using commercial assays, they determined concentrations of chemokine (C-X-C motif) ligand 10 (CXCL10), chemokine (C-C motif) ligand 2 (CCL2) and neurofilament light (NFL), and the proportion of peripheral blood mononuclear cells (PBMCs), and CSF white blood cells (WBCs) active by monocytes (CD14+CD16+) using flow cytometry. Samples were defined as either neurosyphilis or uncomplicated syphilis.

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In patients with neurosyphilis, the median proportion of PBMCs that were activated by monocytes, median CXCL10 levels, CCL2, and HIV RNA were higher compared with patients who had uncomplicated syphilis.

Participants with low MAT scores had higher median CSF, CXCL10 and CCL2 concentrations then those with high MAT scores.

However, neurosyphilis was not associated with low MAT scores.

“Neurosyphilis may augment HIV-associated [central nervous system] inflammation, but it does not explain cognitive impairment in HIV-infected individuals with syphilis,” the researchers concluded.

—Melissa Weiss

Reference:

Ho EL, Maxwell CL, Dunaway SB, et al. Neurosyphilis increases HIV-associated central nervous system inflammation but does not explain cognitive impairment in HIV-infected individuals with syphilis [published online May 19, 2017]. Clin Infect Dis. https://doi.org/10.1093/cid/cix473.