our report tonight from our chief science correspondent robert bazell. >> reporter: 14-year-old ky and his 12-year-old brother kasen spend a lot of time outdoors staying as active as possible. the boys have a tough time sitting still. both were diagnosed with adhd when they were younger. their mom karen first noticed it when the boys had trouble completing simple homework assignments. >> it was such a struggle. we only got six problems done in one hour. in between that time, he just blurted out, he says, mommy, i can't think. i just can't think. >> reporter: according to data collected by the cdc and analyzed by "the new york times," the number of children diagnosed with adhd is increasing. the times analysis shows an estimated 6.4 million, ages 4 through 17, have adhd. those numbers reflect a 50% increase in the past decade. nearly two-thirds of those children get prescriptions with amphetamine-type drugs to help treat the disorder. sales of the drugs reached $9 billion last year. >> i think this is of great concern. i think that there is some overdiagnosis and overtreatment going on

robert bazell, nbc news, st. louis. >>> when we come back here tonight, "candid camera." a rare look behind the scenes of vintage hollywood. >>> it was the top of the seventh at the nationals-reds game in cincinnati when jason worth belted one out of there. but even more memorable was the play in the stands. the one-handed catch by a fan who showed he was clearly capable of multi-tasking. though, not something we would necessarily recommend when holding on to a baby with the other hand. >>> it was an unusual sight today at augusta national in georgia. former secretary of state condoleezza rice took a stroll around the famed golf course as one of the first of two female members to join augusta national. earlier rice played a practice round with none other than phil mickelson who will compete in the masters tournament later this week. >>> their careers were made in motion pictures, but it is some long forgotten still frames of stars from the golden age of movies that are attracting a lot of attention this weekend at an auction here in new york. especially because they were

with more, here's nbc's chief science correspondent robert bazell. >> reporter: six years ago, linda was the very picture of health. she ate right and had frequent check-ups. then she had a heart attack. >> i didn't think i was at risk for a heart attack, number one, because i was very thin. my cholesterol, they checked everything all these years. >> reporter: many people have heart attacks, even though they don't have the well known risk factors including high cholesterol, blood pressure and diabetes. so doctors are always looking for new risk factors. the latest possible culprit, a chemical called tmao. made by bacteria we all carry in our gut. a three-year study of 4,000 people who had been treated for heart disease showed the higher level of tmao in the blood, the greater their future risk. >> a simple blood test that's measuring a bacterial product was able to predict future risk of heart attack, stroke and death independent of existing risk factors or other existing blood tests. >> reporter: where does tmao come from? when a person eats cheese, eggs and red meat, harmless bacte