Health and sickness -- Consumer Health -- Stuttering is an affliction that affects every ethnicity and every culture equally, some sixty million people worldwide. Five percent of children stutter. Typically this debilitating condition emerges when a child is between the ages of two and six. Twenty percent of these children will continue to stutter as adults. Although it is so pervasive, there is great misunderstanding about stuttering. Socially isolating those it strikes, the disorder prevents them from the kind of candid discussions that would help them gain an understanding of it. In turn, social isolation creates misconceptions. In "Understanding Stuttering" a writer who is both a practicing physician and former researcher on stuttering examines the medical roots of the problem and, hoping to bring alleviation, shares his findings. He defines stuttering as a medical condition that is neurologically based or inherited. In clear language he explains the basics of brain anatomy and function, tells of the latest scientific advances in diagnosis and treatment of stuttering, and explains the difference in acquired stuttering and Tourette syndrome. Using examples from his practice, he details effective treatments, including speech therapy and medications. He discusses the most promising new research and tells how the findings of this research will improve treatments and provide a possible cure. "Understanding Stuttering" concludes with practical tips on how to converse with those who stutter and lists organizations that provide additional information and support. Nathan Lavid, a former faculty member at the University of Southern California School of Medicine, is in private psychiatric practice in southern California.