Despite decades of research, disorders of the brain have proved especially difficult to treat. Consider Alzheimer’s disease. To date, every single clinical trial of a treatment for Alzheimer’s has failed to halt its progress. In January, Pfizer announced that it had ended research on drugs for it, as well as for Parkinson’s disease. Autism has been similarly frustrating. Then there is schizophrenia, which has not seen a breakthrough for more than 60 years, since the discovery of chlorpromazine (brand name: Thorazine)—which happened largely by chance.
But the story of chlorpromazine offers a powerful lesson: originally an antihistamine, it was repurposed as an antianxiety medication. That led to doctors trying it in people with pathological anxiety and in agitated psychotic patients. Finally, with a few modifications, it was reborn as an antipsychotic, ushering in a generation of medications to treat a variety of psychiatric disorders, from schizophrenia and bipolar disorder to severe depression and anxiety. These are not miracle cures, and they have serious side effects—but they are far better than what existed before.
As a neuroscientist who has studied schizophrenia for decades, I am convinced that we could have similar successes with other medicines already on our shelves, which may hold untapped promise for treating brain diseases—if only pharmaceutical companies can be prompted to share their data with scientists. Because an existing drug has already passed FDA tests to prove it is nontoxic to humans, successfully repurposing it could take less than half of the estimated 13 years and significantly less than the average $2-billion to $3-billion cost of developing a single drug from scratch. The thousands of FDA-approved drugs thus represent a vast resource that can potentially be modified to target any number of conditions. But this potential is largely unexplored, in part because companies focus on specific diseases and would have to restructure their R&D programs to look at others.