Neuropsychological assessment in HTLV-1 infection: a comparative study among TSP/HAM, asymptomatic carriers, and healthy controls

Background: Human T cell lymphotropic virus type 1 (HTLV-I) can cause tropical spastic paraparesis/HTLV-1 associated myelopathy (TSP/HAM) and adult T cell leukaemia/lymphoma. More recently other diseases such as isolated peripheral polyneuropathy, myopathy, artropathy, and uveitis have been associated with this retrovirus. Only a few uncontrolled studies, without necessary exclusion criteria, have described mild cognitive deficits among TSP/HAM patients. To further clarify this the authors evaluated, through neuropsychological testing patients with TSP/HAM and asymptomatic infected carriers, comparing both groups with healthy controls. Objectives: To verify the presence of cognitive deficits among TSP/HAM patients and asymptomatic HTLV-1 infected carriers. In addition, the authors aimed to investigate if these deficits correlated with the degree of motor impairment in TSP/HAM patients. Methods: From a cohort of 501 HTLV-1 infected people the authors selected, according to predefined inclusion and exclusion criteria, 40 asymptomatic HTLV-1 carriers and 37 TSP/HAM patients. Neuropsychological testing was blindly performed in both groups and their scores were compared with those obtained from controls. Results: Both the HTLV-1 carrier group and the group of patients with TSP/HAM exhibited a lower performance in neuropsychological tests when compared with controls. Asymptomatic infected carriers and TSP/HAM patients did not differ in their cognitive results. Also, there was no relation between the degree of motor disability and cognitive deficits in the TSP/HAM group. Psychomotor slowing and deficits in the some domains characterised the neuropsychological impairment in HTLV-1 infection: verbal and visual memory, attention and visuomotor abilities. Conclusions: TSP/HAM as well as asymptomatic infection can be associated with mild cognitive deficits. This finding, if confirmed by further studies, will permit the inclusion of cognitive impairment among the neurological manifestations of HTLV-1.