Early Head Start, created in 1995 to serve at-risk infants and toddlers, also helped their parents, who were more likely to read and talk to their children and less likely to spank them.
The differences between families in the program and other families were not dramatic, but researchers were encouraged because they were found across a host of measures, suggesting the program may have a lasting impact.
"The fact that they're so widespread gives me a lot of confidence it's making a systemic difference," said John Love of Mathematica Policy Research, one of the lead researchers. "As long as they continue, these children should definitely do better later on."
The program has two different formats. Children either are sent to high-quality child care centers, or experts in child development make weekly visits to families at home.
The centers offer extra services like health care and nutrition counseling, and workers supplement them with at least two home visits a year. For the stay-at-home families, parents and their children also meet with other participants at least twice a month for classes and play time.
During the home visits, a social worker might talk to a mother about problems she is having with her child, about discipline and basic health issues. The worker might play with a baby, demonstrating for how the mother she can encourage development.
For instance, a mother might not realize that her 9-month-old can start looking under a cloth for a hidden object, explained Jeanne Brooks-Gunn of Columbia University, another lead researcher. That may sound simple, she said, but learning that the object remains under the cloth even though the baby cannot see it is one of the ways babies' brains develop.
"You really show the moms things that their kids can do at that age, and how they can play with them," Brooks-Gunn said.
In the child care centers, meanwhile, the workers are talking and playing with children all day long. "Kids aren't wandering aimlessly around the center," Brooks-Gunn said. "They're not sitting there watching TV."
Children typically enter Early Head Start at birth and can remain until age 3. It was created as a warm up for the 35-year-old Head Start preschool program, reasoning that children will be better prepared for preschool - and therefore better prepared for school - if they get more attention in their earliest years, a critical time for brain development.
While Head Start enjoys bipartisan support, critics have argued that there is very little data about its effectiveness. The first national evaluation of Head Start is just now getting under way, so from an academic standpoint, arly Head Start is ahead of its predecessor.
The program's supporters seized on Thursday's study to suggest that the $558 million program, which serves just a fraction of eligible kids, needs more federal money.
"This research confirmed what parents know instinctively," Sen. Edward Kennedy, D-Mass., ranking member of the senate's Health, Education, Labor and Pensions Committee, said in a statement. "Infants and toddlers need extensive individual attention to develop the kind of curiosity, trust, self-confidence and self-control they need to do well in school and in all their future years."
The study, released Thursday by the Department of Health and Human Services, was conducted in 17 cities and compared about 1,500 participants at age 2 with 1,500 2-year-olds whose families wanted to participate but were assigned to the control group instead.
Families in each group were measured on a host of standards. Among the findings:
-About 58 percent of participating parents said they read to their children every day, compared with 52 percent of other parents.
-Participating children had higher average scores on a brain development index that measures memory, problem solving, the ability to name objects and identify shapes, attention span and other tasks. And they were less likely to score dangerously low.
-About 62 percent of participating parents set a regular bed time for their children, compared with 56 percent of other parents.
-About 47 percent of participating parents said they had spanked their child in the last week, compared with 52 percent of other parents.
-Participating parents reported higher vocabulary scores for their kids than others.
-Participating parents were less likely to report aggressive behavior than others.
Researchers plan future reports on the same children at 3 and again when they enter school.
Traditionally, it has been easier to make small, community-based programs work, making the results from this study particularly encouraging, said Olivia Golden of HHS, who headed the 1993 committee that recommended the program.
"It's really thrilling to see that we can make a difference in a program of national scope," she said. "It means you're seeing a lot more than just the effect of one talented teacher."
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