O.C.G.A. § 17-10-69

If an applicant is determined to have previously filed an application under this article and has previously been determined to be mentally competent to be executed, such prior adjudication shall act as a presumption of mental competency and the applicant shall not be entitled to a new hearing on the question of mental competency to be executed absent the applicant’s making a prima-facie showing of a substantial change in circumstances sufficient to raise a significant question as to the applicant’s mental competency to be executed at the time of filing of any subsequent applications.