Methods are provided for the treatment of subjects with cognitive or neuropsychiatric impairment induced by substance addiction and for increasing cognitive function in a subject with substance addiction. In some embodiments, the methods include administering to the subject a therapeutically effective amount of a major histocompatibility complex (MHC) molecule including covalently linked first, second, and third domains; wherein the first domain is an MHC class II β1 domain and the second domain is an MHC class II α1 domain; or wherein the first domain is an MHC class I α1 domain and the second domain is an MHC class I α2 domain; and wherein the third domain is covalently linked to the first domain and comprises an antigen of the central or peripheral nervous system.