CHICAGO (AP) -- Neurological damage in very small premature babies may decrease over time, according to research that tracked children through age 8 and found substantial mental gains.

Many youngsters once considered retarded ended up scoring in the nearly normal range on tests of verbal function and IQ, the study found.

Children who received early intervention such as speech therapy, those from two-parent families, and those whose mothers had high levels of education were found to experience the greatest improvement in mental function.

The findings are surprising because previous research has found negative long-term results for very small preemies, and conventional thinking says that IQ doesn't change -- at least in people born at a normal weight.

"We were thrilled by the findings and surprised because previous reports suggested that there's an adverse outcome for very low birth-weight babies," said lead researcher Dr. Laura Ment, a Yale University pediatric neurologist.

"We found children progressively getting better between 3 and 8 years of age," Ment said.

The study involved 296 children born at 28 weeks and weighing just over 2 pounds on average. Results appear in Wednesday's Journal of the American Medical Association.

Children born extremely prematurely are at risk for a variety of neurological problems, ranging from cerebral palsy, mental retardation and vision trouble to more subtle learning and behavior difficulties.

Ment said the study results echo recent research in animals showing that the developing brain can repair itself.

A JAMA editorial suggests that broader tests of mental function would have had poorer results and notes that IQ improvements were still in the average to low-average range.

"Despite improvements in scores, such low average functioning can place a child at significant academic disadvantage," said editorial author Glen Aylward, a developmental specialist at Southern Illinois University's medical school.

The youngsters were given a test of verbal abilities and three different IQ tests starting at age 3.

The average IQ scores increased from 90 to 95.

The average score on the verbal test increased from 88 points at age 3 to 99 points at age 8. Data from normal birth-weight children suggest average verbal scores improve by about 4.5 points over time, the authors said.

Nearly half of the children with verbal scores in the mental retardation range -- below 70 -- at 3 years of age scored at least in the borderline range -- 70 to 80 -- at age 8. And about two-thirds of the children with borderline scores on both tests at age 3 had scores in the normal range at age 8.

A score of 100 would be average on both the IQ and verbal tests for a normal birth-weight 8-year-old.

Less significant improvements were found in children born with bleeding in the brain -- a common complication in very low birth-weight babies.

Prominent preemie researcher Dr. Maureen Hack was skeptical of the results and said the children studied were not given tests designed to measure problems usually linked with prematurity, such as attention deficits and visual-motor impairments.

Hack also faulted the researchers for not comparing the prematurely born children with youngsters born at normal weight and said the preemies likely would have fared worse if such a comparison had been made.

"I personally feel that basically, the functional problems persist," said Hack, of Rainbow Babies and Children's Hospital in Cleveland.

Copyright 2003 The Associated Press. All rights reserved.