Selective attention function impairment in HIV-negative patients with early forms of neurosyphilis

The attentional network test (ANT) is widely used to evaluate the performance of three attentional networks: alerting, orienting and executive attention networks. This study aimed to investigate the characteristics of attention functions in HIV-negative patients with early forms of neurosyphilis (NS) and their correlation with abnormalities in brain magnetic resonance imaging (MRI).

Thirty patients with early forms of NS, 31 patients with syphilis but without NS (Non-NS) and 35 healthy controls were recruited from an HIV-negative cohort between September 2020 and November 2022. The participants were evaluated with the ANT and the Mini-Mental State Examination (MMSE). Brain MRI was performed in NS and Non-NS patients.

No significant differences were observed in the MMSE scores among the three groups. However, patients with early forms of NS showed poorer performance in orienting and alerting functions than Non-NS group (F = 6.952, P = 0.011 and F = 8.794, P = 0.004, respectively); No significant difference was observed in executive function between the two groups (F = 0.001, P = 0.980). Multivariate analysis of variance using the Bonferroni post hoc test indicated that patients with NS exhibited less efficient orienting function (P = 0.023), and alerting function (P = 0.003) but not executive function (P = 0.99), compared to Non-NS patients. Additionally, a significant difference was found in orienting function between patients with NS and healthy controls (P < 0.001) compared to healthy controls. MRI scans revealed that the NS group had a higher prevalence of abnormalities in the frontal lobes and/or the temporoparietal junction compared to the Non-NS group (24/25 vs. 13/19, P = 0.032).

The orienting and alerting functions but not executive function were significantly less efficient in early forms of NS group than in the Non-NS group (P < 0.01). This indicates deficits in selective attention in patients with early forms of NS. Brain MRI scans revealed abnormalities in the frontal and/or parietal lobes, as well as the temporoparietal junction, suggesting potential neuropathological correlates of these attentional deficits.