Riese v. St. Mary's Hospital & Medical Center (1987) recognized that "mental illness 'often strikes only limited areas of functioning, leaving other areas unimpaired, and consequently . . . many mentally ill persons retain the capacity to function in a competent manner.' Also see: Rivers v. Katz [(1986) 67 N.Y.2d 485 [504 N.Y.S.2d 74, 495 N.E.2d 337, 342]; Rogers v. Okin [(D.Mass. 1979)] 478 F. Supp. [1342,] 1361; Davis v. Hubbard [(N.D.Ohio 1980)] 506 F. Supp. 915, 927 ['roughly 85 of the patients (of a state mental hospital) are capable of rationally deciding whether to consent to (use of psychotropic drugs).']; Brooks, the Constitutional Right to Refuse Antipsychotic Medications (1980) 8 Bull. of Am.Acad.Psychiatry & L.Bull. 179, 191.)" ( Riese v. St. Mary's Hospital & Medical Center, supra, 209 Cal. App. 3d at p. 1321.)