The CNS therapeutic area covers wide range of diseases, including psychiatric and neurological diseases and also symptom classes which span a number of diseases, like pain and spasticity. The diseases share the common property that primary mechanisms leading to expression of the disease are in the brain and spinal cord. Despite the high prevalence of many of these diseases, they are still poorly treated.
Attrition rates for new drug development are higher than any other therapeutic area, and have led to several companies withdrawing resource from the area. Indeed there are issues at every stage of the discovery/development pathway including: an inadequate understanding of the aetiology and pathology, poorly predictive animal models, difficulties with drugs accessing the target organ, subjective clinical endpoints and, in some instances, uncertainty regarding outcomes that regulators will value.
However, the commercial prizes are potentially great and the medical needs high, so the industry cannot disengage from the area altogether.