1. From the Faculty of Medicine (O.S.), University of Iceland, Reykjavik; Department of Neurology (O.S., T.T.), Karolinska University Hospital; Department of Clinical Neuroscience (O.S., T.T.), and Institute of Environmental Medicine (T.A., S.C.), Karolinska Institutet, Stockholm; and Center for Occupational and Environmental Medicine (T.A.), Stockholm County Council, Sweden.