The invention provides methods and compositions for diagnosing prior ischemic stroke or transient ischemic attack (TIA) and approximate the time said stroke occurred, comprising measurement of IgG and IgM antibodies to NR2A and/or NR2B NMDA receptor or fragment thereof in a biological sample, and comparing those measurements to reference population standards and to each other. The invention also includes optionally measuring other biomarkers for autoimmune disease for the reduction in false positives and better risk stratification for future stroke events. The method is particularly useful for identifying individuals that are at risk for future stroke or TIA, and for diagnosing previous history of ischemic stroke or TIA. This measurement and comparison enables determination of the risk of future stroke which is by definition higher in those patients who have suffered a previous stroke. The determining of existence of previous stroke and risk level of future stroke enable optimal therapeutic decisions to reduce risk of future events.
