This volume contains the proceedings of the fifth annual symposium held October 1971 at the Texas Research Institute of Mental Sciences in Houston. We are grateful to Curtin Scientific Company, Fisher Scientific Company, Geigy Pharmaceuticals, The Gerontological Society, ICN Bentex Pharmaceutical Company, Ives Laboratories, Knoll Pharmaceutical Company, Merck Sharp & Dohme Postgraduate Program, The Moody Foundation, The Pauline Sterne Wolff Memorial Home, Pfizer Laboratories, Roche Laboratories, Sandoz Pharmaceuticals, Schering Corporation, and E.R. Squibb & Sons for their generous financial support of the symposium. Special thanks to Dr. William M. McIsaac, director of Texas Research Institute, for his guidance of the symposium series, and to administrator Frank]. Womack and his staff for organizational support. To Drs. Neil R. Burch, James 1. Claghorn, Beng T. Ho, Robert ]. Johnson, and Joseph c. Schoolar, heads of Institute research departments, thanks for their contribution in chairing symposium sessions. To Lore Feldman, who claims all typographical errors, credit for skillful copy editing of the manuscript. Typesetting was done by Gee Lindblom of the medical illustration and audiovisual education department at Baylor College of Medicine. Charles M. Gaitz v Contributors Paul E. Baer, Ph.D. Professor, Departnwnt of Psychiatry, Baylor College of Medicine, Houston, Texas Arthur L. Benton, Ph.D. Professor of Neurology and Psychology, University of Iowa, Iowa City, Iowa James E. Birren, Ph.D. Director, Gerontology Center, University of Southern California, Los Angeles, California Ewald W. Busse, M.D.
