A new branch of "designer" medicine will develop, which is neither treating nor preventing disease, but merely satisfying an insatiable appetite for human pleasure and achievement. It will be highly controversial and its practitioners will be shunned by the rest of the medical profession.
For example, students will be able to add the equivalent of 20 points to their IQ in exams by using memory enhancing, and other stimulatory drugs developed for Alzheimers, while drugs will also be available to let people eat as much as they like without ever growing fat. Others will slow down the process of ageing beyond anything we dream possible today.
Smart drugs will raise huge moral dilemmas because they will be widely used in wealthy nations at a time when millions are still living in terrible poverty in most of the rest of the world. And of course, addiction to a variety of substances will continue to be a major problem, in the medical profession as well as the rest of the population.