Children who struggle with attention and behavior problems tend to end up earning less money, finish fewer years of school and have poorer mental and physical health as adults, compared with children who don't show early attention and behavior problems, according to research published by the American Psychological Association.

Children who struggle with attention are particularly likely to have lower levels of educational attainment as adults, while those who struggle with impulsivity are more likely to end up in trouble with the law, the research found.

"Our study found broad support for the notion that people's early experiences and skills really matter when they reach adulthood, despite everything that happens in between," said study lead author Andrew Koepp, EdM, of the University of Texas at Austin. The research was published in the journal Developmental Psychology.

The study is a "conceptual replication" of an influential paper published in 2011 that examined data from 1,037 children who were born in Dunedin, New Zealand, in the early 1970s and were followed for the next three decades. That research was the first to find large-scale, longitudinal evidence that problems with self-control in childhood were directly linked to negative outcomes in adulthood. It has since been cited more than 5,000 times in other research papers.

A conceptual replication is a study that tests the hypotheses of an original study using different methods and is a key step in advancing science.

"The Dunedin study has received a lot of attention in the research literature and in the popular press over the past decade, but we still did not know whether those findings would replicate with individuals in other countries," Koepp said. "So, our main question was: Does difficulty controlling attention and behavior in childhood predict adult health and success in the U.S. and the U.K., as it did with the sample from New Zealand?"

To investigate that, he and his colleagues examined data from two large cohorts of participants in the United Kingdom and the United States. The U.K. group included more than 15,000 participants in the National Child Development Study, all of whom lived in England, Scotland or Wales, and were born during one week in 1958, and were followed through age 42. The U.S. group comprised 1,168 participants in the Study of Early Childcare and Youth Development, who were born in 1991 at 10 hospitals across the U.S. and followed through age 26.

In both studies, participants, their parents and their teachers were surveyed many times during the participants' childhoods. The surveys included measures of the children's impulsivity, inattention and hyperactivity at home and at school. Later, as adults, participants answered questions about wide-ranging aspects of their lives, including their education, careers, finances, and physical and mental health.

The researchers analyzed the data using similar statistical methods as the Dunedin study and found very similar results—childhood attention and behavior problems were associated with a wide range of poorer outcomes in adulthood.

"We were surprised at just how closely our findings from cohorts in the United States and the United Kingdom lined up with the original study from New Zealand. In fact, in some of the statistical models we ran, the results were identical," Koepp said. "That is great news for our field because it means we are on more solid ground when we say that children's abilities to control their attention and behavior are important life skills. We can now point to longitudinal studies from three countries, comprising three different generations, when we make that assertion."

The researchers' second goal was to look separately at different aspects of attention and behavior. Whereas the original study had looked at these skills broadly, in the current study the researchers wanted to see whether problems with attention and problems with hyperactivity or impulsivity would predict different outcomes. They found evidence that attention problems predicted less educational attainment, and impulsivity problems predicted greater involvement in the criminal justice system.

The researchers also wanted to see whether attention and behavior problems measured at different stages of childhood were more or less likely to predict adult outcomes. The original study had looked at an average of measures taken across participants' childhoods; in the new study, the researchers looked separately at measures taken in early childhood, middle childhood (ages seven to nine) and early adolescence (age 11).

Overall, they did not find evidence that any one period was driving the association between childhood behavior and adult outcomes.

"I think our findings make it clear that identifying ways to help children develop the skills to manage their attention and behavior at any age could pay real dividends and set them on a track for success," Koepp said.