Millions of people around the world are impacted by diseases of the brain — including depression and Alzheimer’s disease. Despite the global demand for better treatments, drug development in this area has been plagued by more failed clinical trials than any other. Behind this trend, industry experts cite a yet incomplete view of the biology behind complex brain diseases. In response, investors and drugmakers are calling for the development of biomarkers to better track disease causes and progression. Such efforts are seeing support from the FDA, as with the accelerated approval of the Alzheimer’s drug Aduhelm based on key biomarker data. Neurological disease experts will weigh three areas of biomarkers that hold promise in advancing treatment development: endpoint selection, diagnostic criteria, and precision medicine. This discussion is increasingly important in a global therapeutic market projected to be worth more than $205B by the year 2028.