* Alan C. Mendelson has joined the board of CoCensys Inc., an Irvine developer of products for treating disorders of the central nervous system. His appointment increases the number of directors to six. Mendelson is a partner in the business department of the law firm of Cooley Godward Castro Huddleson and Tatum. He also serves as head of the firm's companies practice group and managing partner of the firm's Palo Alto office. Mendelson has served as corporate secretary for CoCensys since 1990.