[1] Chonnam Natl Univ, Med Sch, Dept Psychiat, Dong Ku, Kwangju 501757, South Korea
[2] Kwangju City Mental Hosp, Sect Old Age Psychiat, Kwangju, South Korea
[3] Chonnam Natl Univ, Med Sch, Res Inst Med Sci, Dong Ku, Kwangju 501757, South Korea
[4] Inst Psychiat, Sect Epidemiol, London, England