Study reveals that high-achievers are far more likely to be manic depressives . . .The study, led by James MacCabe, a senior lecturer in psychiatric epidemiology at the Institute of Psychiatry, compared the final school exam grades of all Swedish pupils aged 15-16 from 1988 to 1997, with hospital records showing admissions for bipolar disorder up to age 31. . . . They suggest that mania may improve intellectual and academic performance, accounting for the link with "genius". People with mild mania are often witty and inventive, appearing to have "enhanced access to vocabulary, memory and other cognitive resources". They tend to have exaggerated emotional responses which may "facilitate their talent in art, literature or music". In a manic state individuals have "extraordinary levels of stamina and a tireless capacity for sustained concentration".