The WSJ looks at the “bypass brain” phenomenon:

Aides to Bill Clinton last week vehemently denied speculation that the former president’s intemperate remarks on the campaign trail were due to mild cognitive damage from his quadruple-bypass surgery in 2004 . . .

. . . Symptoms include short-term memory loss, slowed responses, trouble concentrating and emotional instability. In a landmark study published in the New England Journal of Medicine in 2001, researchers at Duke University Medical Center tested 261 patients before and after bypass surgery and found that 53% of them had significant cognitive decline when they were discharged — and 42% still suffered from it five years later.