Adding to the debate over using antidepressant drugs for depressed teenagers and children, a group of prominent researchers issued a report yesterday saying that Zoloft and similar medicines did not increase children's suicide risk. The group, drawn from members of the American College of Neuro- psychopharmacology, also found that the drugs were effective in treating children's depression. "Depression in children and adults is the major illness that underlies suicide, and we believe that the S.S.R.I. class represents the medication with the greatest efficacy against this very serious condition," said Dr. J. John Mann, a professor of psychiatry at Columbia University...