BY CHRISTOPHER TENNANTSTUDENT.COM CORRESPONDENTWhen David Green gets ready to write a term paper, he boots up his computer, pulls his chair close to his desk and draws a deep breath. He crushes a tablet of Ritalin beneath a textbook, leans over his desk blotter and inhales the small mound of white powder. The Harvard sophomore says Ritalin, a concentration drug for which he does not have a prescription, helps him focus on his schoolwork. "In all honesty, I haven't written a paper without Ritalin since my junior year in high school. I even wrote my Harvard essay on it," said Green, whose name has been changed to protect his identity. "It keeps you up when you're tired, and makes you much more aware of what you're doing. Although there are certain risks involved, I think it's worth it." From cups of joe to rails of blow, college students' abuse of stimulants is hardly a new phenomenon. Amphetamine-based drugs like Ritalin have long been among the sedulous set's favorite fuels fo!
             r all-night study sessions. But as college becomes more competitive and time grows more precious, students at campuses across the country have begun experimenting with Ritalin. Some swallow pills, while others crush tablets into powder and snort the drug like they would cocaine. Students report abuse has become so common - and students like the drug so much - that fraternities are stockpiling it with the same vigilance they take to ensure they never run out of beer. Abuse Began at Northeast Prep Schools Ritalin abuse was first noticed at New England prep schools, where access is easy because so many students have Ritalin prescriptions - often not warranted by medical need, said Dr. Eric Heiligenstein, head of psychiatry for the University of Wisconsin Health Services. "The first time I ever heard about Ritalin abuse was a few years ago, from a student who had gone to a prep school in Connecticut," Heiligenstein said. The student "talked about ...