MONDAY, April 2 (HealthDay News) -- About 10 percent of children with autism experience rapid gains in skills -- progressing from severely affected to high functioning -- but minority children with less-educated mothers are much less likely than richer white kids to fall into this group, a new study suggests.

Analyzing nearly 7,000 California children with autism, researchers from Columbia University in New York City also found that these kids typically display six typical patterns of social, communication and repetitive behaviors and that those whose symptoms were least severe at diagnosis tend to improve more quickly than others.

"These children follow really different pathways over time, changing at very different paces and according to very different patterns," said study author Christine Fountain, a postdoctoral researcher at Columbia's Institute for Social and Economic Research and Policy. "Most children do get better, at least a little bit. But we found it somewhat surprising that about 10 percent improve really rapidly and to a great extent."

The study is published online April 2 and in the May print issue of the journal Pediatrics.

According to information released Thursday by the U.S. Centers for Disease Control and Prevention, about 1 in 88 American children has autism, a developmental disorder characterized by deficits in communication and social interaction along with repetitive behaviors.

The new study, which didn't examine the effects of autism treatments or interventions, observed symptom trajectories in participants born between 1992 and 2001 from diagnosis through age 14. Factors examined also included race, ethnicity, mothers' education level, gender and socioeconomic status.

Most improvements in autism symptoms occurred before age 6, the study said, and the rapidly improving group -- dubbed "bloomers" -- started with low scores and ended with scores comparable to patients in high-functioning groups.

"We were really pleased that there is this group, which is relatively small but significant, who are able to improve so quickly," Fountain said. "It's going to provide a hopeful message for parents [of autistic children]. We need more research to find exactly what's going on to make these children bloom."

While communication and social behaviors might improve more dramatically in some children, the study found that patterns of repetitive behaviors -- which can include hand-flapping and head-banging -- tended to remain relatively stable, improving or worsening in only about 15 percent of children over time.

Minority children whose parents were in the lowest socioeconomic groups were much less likely to be "bloomers" than those with more advantages, the study said. Among all children with autism, those with accompanying intellectual disabilities were more likely to stay in the low-functioning groups.

Based on the socioeconomic differences, expanding minority children's access to early treatment and educational services seems critical, the authors said.

Another expert said the study will help those working with children who have autism. "I think what's impressive is that this study documents what clinicians have seen -- that there can be a very variable outcome among children with autism and that all things being equal, the children that do best over time are those who start out with less impairment and less intellectual disability," said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at the Steven and Alexandra Cohen Children's Medical Center of New York, in New Hyde Park.

The study was limited because its data didn't offer reasons why some children with autism improve more than others, Adesman said, other than pointing to differences in ethnicity or socioeconomic status. But, "to some extent, this study helps us identify the likely range of outcomes, which is going to be helpful for clinicians," he added.

More information

The U.S. National Library of Medicine had more about autism.