This study is an open label 6 month study. All subjects will be treated with Polyphenon E (400 mg EGCG twice a day) for six months. The main outcome of this pilot phase will be safety. Secondary outcomes are the change in NAA levels over 6 months as measured by MR-spectroscopy. NAA levels are a marker of neuronal function. We think that Polyphenon E will protect neurons and thus increase NAA levels.