Low-income students who participate in preschool programs such as Head Start do better for many years afterward in school, according to followup studies conducted in some cases as long as 13 years after the preschool programs.

The followup studies of 820 such children were summarized and evaluated by a research team headed by Drs. Irving lazar and Richard B. Darlington at Cornell University. They show that the students generally are held back less frequently, are placed in special education classes less, score better than a control group on math achievement tests, have a higher self- image, and do better on IQ tests for at least three years after the preschool programs.

In some cases, according to Dr. Bernard Brown, a research analyst at the Department of Health, Education, and Welfare, it is five to six years after the preschool programs.

The studies -- which Brown said are only the latest in a series over the past few years -- "refute the notion that the results of 'early intervention' are worthless," he said.

Preschool enrichment programs like Head Start, with relatively small groups, parent involvement, special efforts to improve children's use of language, edcational toys and an atmosphere designed to encourage learning and self-acceptance, were hailed in the early 1960s as a possible panacea for low-income children.

But the so-called Westinghouse report in 1969 cast doubt on whether any beneficial effects lasted more than a brief period.

Now, according to the Lazar-Darlington report, which was distributed by HEW, a whole series of followup studies is beginning to change the view engendered by the Westinghouse report.

The Lazar-Darlington report summarizes followup studies done in 1977 on eight groups of students who had participted in preschool programs.

By 1977, some of these students were 18 to 19 years old and had been out of the program 13 years. Others were younger and had been out only four or five years.

About 90 percent of the children were black, most were poor and many had spent long periods without a father in the home.

These are some of the findings:

Preschool children were assigned to special education significantly less than a control group. In one group in North Carolina, children who had participated in a preschool program (based on learning materials and techniques being brought into the child's home by having a "visitor" work with the parent and child), had a 23 percent assignment rate to special education later, but the control group rate was 54 percent.

Children who participated in preschool programs later were held back less -- in some cases, only half as much as the control group, in others just slightly less.

Four or five years after preschool, the children did significantly better in math than the control group, which didn't attend preschool. In one representative group, those who had preschool were over a half-grade ahead in math.

Preschool children scored higher in IQ for up to three years afterwards, and in some cases up to five or six years, according to Brown. "four years ago we thought the IQ improvement faded in a year," Brown said.