"The term `incompetent adult' means an adult or emancipated minor who lacks sufficient capacity to manage the adult's own affairs or to make or communicate important decisions concerning the adult's person, family, or property whether the lack of capacity is due to mental illness, mental retardation, epilepsy, cerebral palsy, autism, inebriety, senility, disease, injury, or similar cause or condition." [G. S 35A-1101(7)]