Characteristics of Brain Structure in HIV Male Patients with Syphilis Co-Infection: A Cross-Sectional Study.

Background: To investigate the effect of syphilis infection on the microstructure of white matter (WM) in HIV-infected male patients through comparing the differences of WM between HIV-infected male patients with and without syphilitic infection using diffusion tensor imaging (DTI). Methods: 27 HIV-infected male patients with current syphilis or a history of syphilis (HIV+/syphilis+) and 29 HIV-infected male patients without syphilis co-infection history (HIV+/syphilis-) were enrolled. All patients received DTI and comprehensive neuropsychological assessment. Clinical data were compared between the two groups with T-test, Mann-Whitney U Test and Chi-square Test. Tract-based spatial statistics (TBSS) was adopted to analyze the DTI metrics. Multiple linear regression analysis was conducted to investigate the relationships between DTI metrics and clinical variables and cognitive performance. Results: In the HIV+/syphilis+ group, decreased AD was found in the right superior corona radiata (SCR-R) and body of corpus callosum (BCC); increased RD was found in the bilateral posterior corona radiata (PCR), the right posterior thalamic radiation (PTR-R), the left SCR (SCR-L), splenium of corpus callosum (SCC) and BCC; decreased FA was found in multiple regions. AD in BCC was negatively correlated with CD4/CD8 ratios. AD in SCR-R was positively correlated with CD4/CD8 ratios. Patients in HIV+/syphilis+ group had a lower score in complex motor skills (CMS). RD in SCC and SCR-L was negatively correlated with CMS; RD in PTR-R was positively correlated with CMS. AD in SCR-R was positively correlated with CMS. Conclusions: Compared with patients simply infected with HIV, the integrity of WM is more seriously impaired in HIV-infected patients with syphilis co-infection, and it may accelerate the impairment of cognitive function.