Most mental health conditions are still classified and diagnosed solely based on the symptoms observed, as there are few objective biomarkers for these conditions compared to other conditions, such as diabetes. Although many different neuropsychiatric diseases share symptoms, there is still limited knowledge about the underlying biological cause of a specific disease. For example, we do not really have any idea how, if at all, the biological cause for social withdrawal in Alzheimer’s disease differs from that in schizophrenia.
This lack of understanding of the root biological causes is one of the reasons behind the dramatic slowdown in the development of new drugs to treat neuropsychiatric disorders. Historically, many of the major drug classes for psychiatric disorders were discovered as a consequence of chance observations in human studies, an approach that suffers from a high rate of attrition and risk of drug candidate failures during development.
Modern drug design aims to reduce this risk of attrition by altering a known biological process and closely monitoring and quantifying the treatment effects of this approach. The emergence of new ways of measuring brain activity (e.g. functional Magnetic Resonance Imaging (fMRI) of the brain, which registers blood flow to functioning areas of the brain) is for the first time opening the door to applying this type of drug discovery to mental health conditions.