Finally, the FDA-approved compound cysteamine is thought to increase brain levels of BDNF by stimulating its release through an interaction with the heat-shock protein HSJ1b.93 A recent trial of cysteamine in HD patients has recently completed, but although a suggestion of motor improvement occurred in a subgroup analysis, the primary efficacy endpoint was not met; the full results of the trial, and its open-label extension, are awaited.94 Here, BDNF is linked to Huntington disease.