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Studies of cognitive function in subjects with human immunodeficiency virus type 1(HIV-1)infection who remain relatively asymptomatic(ie,Centers for Disease Control stages II and III)have provided widely variable estimates of cognitive impairment.In view of the finding that approximately 25%of asymptomatic HIV-1-infected subjects demonstrate either marginal or overt vitamin B12 deficiency,we have investigated plasma vitamin B12 status as a potential cofactor in studies of HIV-1- related cognitive impairment.When cognition was assessed in asymptomatic (Centers for Disease Control stages II and III)HIV-1-infected participants taking into consideration vitamin B12 status,those subjects with low plasma vitamin B12 levels(<180pmol/L)performed more poorly than did those with normal(>/=180 pmol/L)vitamin B12 status on specific measures of information processing speed and visuospatial problem-solving skills.These findings suggest that concurrent vitamin B12 deficiency may be a cofactor in subtle cognitive changes observed in the asymptomatic stages of HIG-1 infection.These differences in prevalence of low plasma vitamin B12 levels may help to explain differences among studies in the proportion of HIV-1- infected subjects showing cognitive impairment. |
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