1. Departments of Neurology (N.A.A., A.W.M.v.d.G., R.A.C.R.), Leiden University Medical Center, 2300 RC Leiden, the Netherlands
2. Endocrinology and Metabolic Diseases (H.P., F.R.), Leiden University Medical Center, 2300 RC Leiden, the Netherlands
3. Clinical Chemistry (M.F.), Leiden University Medical Center, 2300 RC Leiden, the Netherlands