Evidence of autism can be identified in the composition of blood vessels in the brain, and certain defects or malfunctions in these vessels could serve as a new basis for detection, scientists have found.
While previous research has focussed on the neurological structure and function in a patient's brain, a team from New York University (NYU) has found evidence of the disorder in the vascular system, suggesting that this could be a new target for medical treatments.
"Our findings show that those afflicted with autism have unstable blood vessels, disrupting proper delivery of blood to the brain," says lead researcher, Efrain Azmitia.
"In a typical brain, blood vessels are stable, thereby ensuring a stable distribution of blood," she adds. "Whereas in the autism brain, the cellular structure of blood vessels continually fluctuates, which results in circulation that is fluctuating and, ultimately, neurologically limiting."
Azmita and her colleagues figured this out by examining the auditory cortex region in human postmortem brain tissue from people with diagnosed autism spectrum disorder (ADS) and an age-matched control group. To mitigate bias, they stripped the samples of all identifiers so they couldn't tell which was which when examining them at a cellular level.
They found significant increases of two types of protein, called nestin and CD34, in the autistic brain vessels, but not in the control brains, which indicated that the vessels of the autistic patients had a higher level of plasticity. This protein surge was identified in several sections of the autistic brains, including the superior temporal cortex, the fusiform cortex (or face recognition centre), the pons/midbrain, and cerebellum.
This kind of plasticity is characteristic of a process known as angiogenesis, which controls the the production of new blood vessels. Publishing in the Journal of Autism and Developmental Disorders, the researchers suggest that evidence of angiogenesis in autistic brain tissue indicates that these vessels are being formed over and over and are in a state of constant flux. This could mean that inside the brains of people with autism, there's a significant level of instability in the blood's delivery mechanism.
"We found that angiogenesis is correlated with more neurogenesis in other brain diseases, therefore there is the possibility that a change in brain vasculature in autism means a change in cell proliferation or maturation, or survival, and brain plasticity in general," said one of the team, psychiatrist Maura Boldrini. "These changes could potentially affect brain networks."
So what now? The researchers hope to continue their investigation into how blood vessels in the brain differ in people with and without ADS, and if they can confirm angiogenesis markers as a reliable indication of the disorder, they could have a new detection method on their hands, and perhaps even a new avenue of research for future treatments.
"It's clear that there are changes in brain vascularisation in autistic individuals from two to 20 years that are not seen in normally developing individuals past the age of two years," says Azmitia. "Now that we know this, we have new ways of looking at this disorder and, hopefully with this new knowledge, novel and more effective ways to address it."