The capacity required to create, amend, revoke, or add property to a revocable trust, or to direct the actions of the trustee of a revocable trust, is the same as that required to make a will.
Capacity of settlor of revocable trust
S.C. Code Ann. § 62-7-601, under Title 62, Chapter 7.
S.C. Code Ann. § 62-7-601