[1] Inst Res & Dev, Colombo, Sri Lanka
[2] Kings Coll London, Inst Psychiat, London WC2R 2LS, England
[3] Teaching Hosp, Dept Med, Professorial Unit, Anuradhapura, Sri Lanka
[4] Univ Sydney, Sydney Med Sch, Sydney, NSW 2006, Australia
[5] Univ London, London, England
[6] Univ Peradeniya, Fac Allied Hlth Sci, Kandy, Sri Lanka