Cognitive impairment in HTLV-1-associated myelopathy, proviral load and inflammatory markers

•HTLV-1 infections are a health problem in many countries, and most of the time are a neglected disease.•There are few studies (seven manuscripts in Medline) about cognitive decline associated with HTLV-1.•This manuscript suggests cognitive impairment may be a long-time complication of HTLV-1 infection.•Cognitive impairment in HAM/TSP seems to be linked to persistent inflammatory activity. Myelopathy is a well-established long-term clinical manifestation of HTLV-1 infection. Besides motor dysfunction, cognitive impairment may be another consequence of HTLV-1 infection. Moreover, inflammatory markers may be associated with cognitive impairment in these patients. The present study compared the cognitive performance of HAM/TSP patients with healthy controls and investigated the associations between cognitive performance, proviral load and blood inflammatory markers. Eighty-three patients fulfilling diagnostic criteria for HAM/TSP were submitted to a comprehensive clinical, cognitive and functional evaluation, brain magnetic resonance imaging and determination of levels of IL-1β, IL-6, TNF-α, immunoglobulins and HTLV-1 proviral load in blood and cerebrospinal fluid. The control group was composed of 88 cognitively healthy subjects, matched for age, sex and educational level. Compared to healthy subjects, HAM/TSP patients displayed significant global cognitive impairment and executive function deficits. HAM/TSP cognitive impairment was significantly associated with altered levels of IgM, IgG, IL-6 and TNF-α in blood. There was no association between HAM/TSP cognitive impairment and HTLV-1 proviral load. This study suggests cognitive impairment may be a long-term clinical manifestation of HTLV-1 infection, which seems to be linked to the persistent inflammatory activity that is found in the disease.