Three areas that are attracting attention are movement and endurance, attention and learning, and moods. Medicines such as anabolic steroids can already make people stronger, swifter and more enduring.
A memory drug might cause subjects to remember too much detail, cluttering the mind, for example. Martha Farah, a psychologist at the University of Pennsylvania, says: "The brain was designed by evolution over millennia to be well adapted because of the lives we lead. We are better served by being able to focus on the essential information than being able to remember every little detail. We meddle with these designs at our peril."