Following the successful progress of gene therapies in treating rare disease, they are now beginning to be applied to CNS disorders, including Parkinson's and Alzheimer's disease, and other serious conditions. Drug delivery to the brain has long been a challenge, and a great deal of research is being focused on identifying various strategies that are able to ferry medicines across the blood-brain barrier (BBB), which typically blocks the transport of molecules and particles into the brain, and effectively deliver their therapeutic payloads. In this two-part feature, the progress being made in the field will be explored.

Although many public biopharmaceutical companies have struggled to find traction this year, those that are concentrating on developing therapies to treat neurological diseases have performed very well. As a result, by the end of April, the BioWorld Neurological Diseases index, a price-weighted index of representative companies that are developing therapies for CNS diseases, had climbed more than 17% compared to a 14% rise in the Dow Jones Industrial average.