CD40LG and Cognitive impairment: Another study, also investigating the relationship between Toxoplasma infection and cognitive impairment in nonpsychiatric controls, bipolar subjects, and patients with schizophrenia, reported a significant association between the anti-Toxoplasma IgM (but not IgG) levels and cognitive impairment in the nonpsychiatric controls in RBANS total score, immediate memory, language, and visuospatial/constructional ability.