Washington, September 27 : The symptoms of the brain development disorder autism can improve with age, says an assistant professor of social work at Washington University in St. Louis.

The new finding is based on a study whose first author Paul T. Shattuck worked on it as a graduate student and post-doctoral fellow at the University of Wisconsin-Madison's Waisman Center.

"On average, people are getting better. It is a hopeful finding, but the fact remains that those with severe autism will depend on others for their everyday needs and care for the rest of their lives," says Shattuck.

Marsha Mailick Seltzer, a Wisconsin professor of social work and the director of the UW-Madison Waisman Center, led the groundbreaking longitudinal study that involved more than 400 adolescents and adults suffering from autism and their families.

Half of the study's participants were from Wisconsin, while half from Massachusetts. They were recruited from service agencies, schools and clinics.

The researchers interviewed parents in the study after every 18 months to assess changes in their children’s symptoms and behaviours.

Shattuck said that behaviour in 241 adolescents and adults, initially aged 10 to 52 years, changed over a five-year period. While symptoms for many in the study remained stable, a significant proportion exhibited improvements in symptoms and maladaptive behaviours, he added.

"For all major symptoms, the percentage of people who improved was always greater than the percentage who worsened. If there was significant symptom change over time, it was always in the direction of improvement, though there was always a group in the middle that showed no change. The mean never went down," Shattuck said.

During the study, changes across 32 specific symptoms within the broad categories of impaired verbal and nonverbal communication, impaired social interaction, and repetitive behaviours were observed.

The changes included reciprocal conversation and interest in people to compulsions and rituals.

The researchers also examined broader maladaptive behaviours such as aggression and self-injury that are not specific to autism. They say that across all categories, the proportion of study participants who improved was larger than the proportion that worsened.

"Not everyone on the autism spectrum is mentally retarded, but being mentally retarded reduces the likelihood of improvement for many symptoms," Shattuck says.

The researcher revealed that it is being investigated as to why some in the sample improved.

"Our study demonstrates that significant changes are occurring. But in terms of the underlying biological mechanisms, we don't yet know what's going on," he says.

The research has been reported in Journal of Autism and Developmental Disorders. (With inputs from ANI)