Doctors said that the report, being published in The Proceedings of the National Academy of Sciences, helps to explain why so many children grow out of the diagnosis in middle school or later, often after taking stimulant medications to improve concentration in earlier grades.

The findings in the first study grew out of a collaboration among a dozen leading researchers to reassess data from six large child-development studies performed since 1970. Each of these six studies tracked hundreds of children from an early age through elementary school on a number of measures, including reading and math skills, emotional stability and concentration, or attention. Most of the studies used teacher reports to gauge students’ emotional and social progress and their ability to pay attention when asked.

The researchers adjusted the findings to eliminate the influence of factors like family income and family structure.

While there was little correlation between behavior problems in kindergarten and later academic success, the researchers did find that scores on math tests at ages 5 or 6 were highly correlated with academic success in fifth grade. Kindergarten reading skills and scores on attention measures — where youngsters with A.D.H.D. falter — also predicted later academic success, but less strongly than math scores did. The pattern was about the same in girls as in boys, and for children from affluent families as well as those from lower-income groups.

The authors of the study suggested that preschool programs might consider developing more effective math training. The findings should also put to rest concerns that boys and girls who are restless, disruptive or withdrawn in kindergarten are bound to suffer academically.

“For kindergarten, it appears teachers are able to work around these behavior problems in a way that enables kids to learn just as much as other kids with equal levels of ability,” said the lead author, Greg J. Duncan, a professor of human development and social policy at Northwestern University.

The findings, Dr. Duncan said, have been “very controversial among developmental psychologists who have seen the paper.”