Canadian researchers find link between autism, schizophrenia

From the Vancouver Sun in Canada:

VANCOUVER, Canada -- Simon Fraser University researchers have found that autism and schizophrenia are both caused by faults in the same set of genes, raising hopes that an effective test or treatment for one may be adapted for use on the other.

The finding is a radical departure from conventional medical thinking about the two disorders as separate and distinct illnesses, according to evolutionary biologist Bernard Crespi, but it opens the door to new avenues of research into the cause and potential cure for each.

Crespi and his co-authors, Philip Stead and Michael Elliot, now believe that autism and schizophrenia are related but opposite illnesses, each caused by anomalies in the same places in the human genome, our genetic blueprint.

Knowing where to look in the genome could help scientists identify which of the dozens of gene mutations that can lead to autism and schizophrenia are peculiar to both. Researchers hope that treatments can then be tailored very specifically and exploited, in different ways, to treat both disorders.

“It’s just like what people are actually doing now with cancer,” Crespi explained. By identifying certain receptors on cancer cells, drug treatment can be designed to target them specifically.

“In principle, something very similar can be done with autism and schizophrenia,” he opined.

A drug to treat schizophrenics that increases activity in certain chemical pathways in the brain could point the way to a drug that decreases the same activity and prove useful for treating autism.

“You could develop opposite therapeutic treatments,” Crespi said. “That’s one of the direct implications if the disorders are opposites.”

Crespi, Stead and Elliot are forging a new path, mostly alone.

The idea that autism and schizophrenia are disorders on a single continuum had been proposed by psychologist Daniel Nettle, who coined the idea based on studies of patient behaviour, but had not tested the notion genetically.

“Autism and schizophrenia have always been regarded as being quite similar, but our data pretty much says the opposite,” Crespi said. “The idea of two psychiatric illnesses being opposites is quite a controversial one.”

Both illnesses involve a malfunction in understanding and processing social signals and behaviours, but in opposite ways, he said. Severe autistics cannot interact socially and may regard other people as little more than objects. Schizophrenics attach too much meaning to people and their actions, perceiving intentions and relationships that do not exist.

Perceiving meaning, a sense of self and complex social interaction represent the most recent advances in human evolution and in autistics, those abilities are severely curtailed while in schizophrenics they are overactive.

“It’s like there is a switch that can dial human evolution up and down,” Crespi said.

The SFU group found that variations in four sets of genes are related to both autism and schizophrenia. People normally have two copies of each gene, but in autistics some genome locations have only single copies and in schizophrenics extra copies are present at the same locations.

The same anomalies also appear to influence abnormal brain growth and head size, with overdevelopment of the brain common in autistics and underdevelopment associated with schizophrenia. Crespi says the brain size associations are consistent with his theory that autism and schizophrenia are diametric conditions.