The challenging hunt for molecular biomarkers of neurological disease For the past 50 years, we have relied primarily on observational tests of behaviour to diagnose mental health issues and disease. In contrast, we have become very reliant on diagnostic tests for identifying most illnesses. Why does this dichotomy exist? Apart from the fact that the brain is in a strong box, it has been very hard to find good proxies for the chemistry and biology of the brain in other tissues. Though modern technologies are helping in breaking down these walls, we need the help of citizens to map what is "normal" before understanding what goes amiss in disease.