A drug can improve the effectiveness of a behavioural treatment for fearful memories, at least in mice.

Long-term memories of traumatic events, which can result in anxiety disorders, are difficult to treat, in part because they leave epigenetic, or chemical, marks in the genome. Li-Huei Tsai at the Massachusetts Institute of Technology in Cambridge and her colleagues tested an HDAC inhibitor, a drug that clears epigenetic markers, on mice that were conditioned to freeze in fear when they heard a loud sound. Conditioned mice given the drug, and then exposed to the sound in a safe environment, froze much less frequently than mice that did not receive the drug. The inhibitor made it easier to replace the bad memory with a less fearful one by changing the expression of the genes involved in rewiring the brain, the authors say.

Cell 156, 261–276 (2014)