Advances in biomarker development are revolutionizing the way we study, diagnose and treat disease. However, progress in the development and use of biomarkers for diseases of the central nervous system has been limited by a number of difficulties--including the inherent barriers associated with studying the brain. Development of reliable biomarkers for brain disorders would dramatically accelerate research on the etiology, pathophysiology, disease progression, and therapeutic development of many very prevalent and devastating diseases including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and others. International experts in the field discuss the latest advances in biomarker technologies and biomarker development for brain disorders.