Relevant quote from The Jargon File (http://catb.org/jargon/html/weaknesses.html):
"Many hackers have noticed that mainstream culture has shown a tendency to pathologize and medicalize normal variations in personality, especially those variations that make life more complicated for authority figures and conformists. Thus, hackers aware of the issue tend to be among those questioning whether ADD and AS actually exist; and if so whether they are really ‘diseases’ rather than extremes of a normal genetic variation like having freckles or being able to taste DPT. In either case, they have a sneaking tendency to wonder if these syndromes are over-diagnosed and over-treated. After all, people in authority will always be inconvenienced by schoolchildren or workers or citizens who are prickly, intelligent individualists — thus, any social system that depends on authority relationships will tend to helpfully ostracize and therapize and drug such ‘abnormal’ people until they are properly docile and stupid and ‘well-socialized’.
So hackers tend to believe they have good reason for skepticism about clinical explanations of the hacker personality. That being said, most would also concede that some hacker traits coincide with indicators for non-hyperactive ADD and AS — the status of caffeine as a hacker beverage of choice may be connected to the fact that it bonds to the same neural receptors as Ritalin, the drug most commonly prescribed for ADD. It is probably true that boosters of both would find a rather higher rate of clinical ADD among hackers than the supposedly mainstream-normal 3-5% (AS is rarer at 0.4-0.5%)."