Three microRNAs that suppress the expression of enzymes involved in neurosteroid synthesis are upregulated in the cerebral white matter of patients with multiple sclerosis (MS), a Canadian study shows. Levels of neurosteroids such as allopregnanolone were reduced in the brains of these patients, and allopregnanolone treatment in a mouse MS model ameliorated some of the neuropathological and neurobehavioral features of the disease. These findings raise the possibility of using neurosteroids as biomarkers or therapeutic agents in MS.