One dose of a century-old drug originally used to treat African sleeping sickness could reverse symptoms of autism in mice.

The medicine, dubbed suramin, stopped a heightened stress response in neurons that is believed to be linked to autism, AAAS Science reported.

The findings suggest certain aspects of autism can be reversed even in adulthood. Many parents describe their autistic children as being caught behind a "veil."

"Sometimes the veil parts, and the children are able to speak and play more normally and use words that didn't seem to be there before, if only for a short time during a fever or other stress" Robert Naviaux, a geneticist at the University of California, San Diego, who specializes in metabolic disorders said, AAAS reported.

A 2007 study found that 83 percent of children with autism show temporary symptom improvement in the event of a high fever.

Many believe autism is caused by scrambled signals at synapses (where nerve cells connect; since something like a fever could improve autism symptoms Naviaux wondered if the problem existed "higher up" in the cell's metabolism.

The research team looked at a process called the "danger cell response," in which the cell protects itself from threats such as infection and temperature changes.

 "The cells behave like countries at war. They harden their borders. They don't trust their neighbors," Naviaux said, AAAS reported.

If the cells performing this response are neurons it could hinder communication and result in social difficulties.

ATP, which carries energy within a cell and delivers messages to neighboring cells, could be the "key player." If too much ATP is released over an extended period of time it can trigger the cell danger response in nearby neurons, contributing to the symptoms of autism.

The drug Suramin has the ability to call off this response. Researchers tested the drug in mice with an autism-like disorder and whose mothers had been exposed to a simulated viral infection which triggered a cell danger response during pregnancy.

The team found that the symptoms vanished in the offspring after they were given weekly suramin injections starting at the age of six-weeks (equivalent to a 15-year-old-human). Immune system symptoms such as "structure of synapses, body temperature, the production of key receptors, and energy transport within neurons," also improved, AAAS reported.

The researchers are unsure if the method will be effective in humans.