Intriguing question. Brain fag is a disorder not formally recognized by psychiatrists, and as far as I know there have been no research studies of whether it responds to any particular treatments. From what I know, it's often referred to in psych textbooks as a "culture-bound" disorder, a set of symptoms complained of only in some African countries, and often related to problems in studying hard for one's education. I have seen it described, but have found, over the years, NO descriptions of treatments, successful or otherwise. Street drugs, including stimulants would NOT be a good idea, as they'd be likely to compound the problems. One's best bet would be to see a good local psychiatrist for a thorough assessment, as there may well be some more widely recognized problem underlying the picture of brain Fag, such as depression or an anxiety state, which do respond well to normal Western medications. Oherwise, counselling, especially of the CBT sort, would be likely to help.