Cognitive deficits in HTLV-1 patients

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus known to be associated with adult T-cell lymphoma and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Previous researches and brain imaging techniques have suggested cognitive abnormalities as well as brain damage in individuals infected with this virus. Given the insufficient amount of studies on how this virus can impact the affected person's cognition, we aimed to assess and compare the cognitive abnormalities of HAM/TSP patients, asymptomatic HTLV-1 carriers, and healthy controls. This cross-sectional study was conducted on 51 patients divided into 3 groups; a group of HAM/TSP patients, a group of asymptomatic HTLV-1 carriers, and an uninfected control group. Each group contained 17 members. The cognitive state of the studied population was assessed using the Mini-Mental State Exam (MMSE), Symbol Digit Modalities Test (SDMT), Rey-Osterrieth complex figure test (ROCF), the "Verbal Fluency Test" and the "Trail Making Test" (TMT) components of the Delis-Kaplan executive function system (D-KEFS) test, the Rey Auditory Verbal Learning Test (RAVLT), and digit span memory test. Patients diagnosed with HAM/TSP received significantly lower scores on the SDMT, ROCF, TMT, RAVLT, digit span memory test, and the orientation, calculation, and recall component of the MMSE assessment (p-value < 0.001). In addition, the asymptomatic HTLV-1 carriers obtained lower scores on the SDMT, ROCF, digit span memory test, and the orientation, calculation, and recall component of the MMSE assessment compared to the control group (p-value < 0.001). Overall, the findings suggest that HAM/TSP, or an asymptomatic infection with HTLV-1 could lead to cognitive deficits in the affected individuals. This can further emphasize the importance of assessing the cognitive function and psychiatric abnormalities of those infected with this virus.