NEWS: Autism linked to overactive immune system, study finds

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Autism linked to overactive immune system, study finds

By ANDRÉ PICARD

PUBLIC HEALTH REPORTER

UPDATED AT 9:41 AM EST Tuesday, Nov 16, 2004

Autism, a mysterious and increasingly common disorder, may be caused, at

least in part, by a malfunction in the immune system, a new study suggests.

Researchers studying the brains of people with autism say they have found

strong evidence that parts of the immune system were overactive, causing

chronic inflammation. This inflammation appears to cause damage to the brain

in a manner similar to what is seen in other neurodegenerative conditions

such as Alzheimer's disease, Parkinson's and amyotrophic lateral sclerosis

(ALS or Lou Gehrig's disease). Autism is a brain disorder that appears in

early childhood. The cause, or causes, are unknown, though immune reactions

have long been suspected as playing a role.

" These findings reinforce the theory that immune activation in the brain is

involved in autism, " said Dr. Pardo Villamizar, a neuroimmunologist

at s Hopkins University School of Medicine in Baltimore, Md.

There are a number of theories about what triggers the damaging

inflammation, including birth trauma, exposure to toxins, childhood

vaccines, diet and viruses.

The new research throws cold water on a number of these notions, suggesting

strongly that immune system problems begin in the womb -- likely in the

second trimester when the nervous system is developing -- and continue

throughout life.

The study, published in today's edition of the ls of Neurology, was

conducted using the brain tissue of 11 people with autism, aged 5 to 44, who

died from accidents or injuries. The victims' brains were donated to a large

U.S. autism tissue program that promotes research.

Researchers measured a number of immune-system proteins called cytokines and

chemokines, and found abnormal patterns that suggested chronic inflammation.

These measures were compared to those conducted on non-autistic victims who

died in similar circumstances, which showed no such inflammation.

" The pattern of cellular and protein findings indicated that they are part

of the innate immune system and do not appear to be caused by immune

abnormalities outside the brain, " Dr. Pardo said.

He said the inflammatory response -- which is one way the immune system

responds to threats -- indicates the brain is fighting back against some

other process that is damaging brain cells.

What is not clear is what is triggering the immune system to become

overactive during fetal development. The cause could be genetic,

environmental, or a combination of the two, Dr. Pardo said.

He said the finding opens the door to the possibility that once the

mechanism is unravelled, a simple measure may exist to prevent autism,

perhaps one as devilishly simple as folic acid supplementation, which has

virtually eliminated neural tube defects like spina bifida and anencephaly.

Those devastating neurological conditions turned out to be caused by a

deficiency in one micronutrient.

Autism is a spectrum disorder, meaning symptoms can vary broadly in those

who are afflicted, from mild to disabling. Generally speaking, children with

autism have difficulty with social interaction and communication, can

display repetitive behaviours and develop unusual attachments to objects and

routines.

Autism is often complicated by the presence of other neurodevelopmental

conditions, such as Fragile X syndrome, Down syndrome (both common forms of

mental retardation) and epilepsy. It is estimated that between two and five

in every 1,000 children born will develop autism before school age. The

Autism Society of Canada estimates the incidence rate in this country is one

in every 286 births. The condition is about four times more likely in boys

than girls.

As part of their study of the immune-system response, researchers also

examined the cerebrospinal fluid of some autistic people, where they found

corroborating evidence of chronic inflammation.

Dr. Zimmerman, a pediatric neurologist at Kennedy-Krieger Institute

in Baltimore and a co-author of the research, said this means it may be

possible to diagnose children with autism by testing the spinal fluid.

He said it is also conceivable that autism could be treated with

anti-inflammatory drugs (such as over-the-counter painkillers) but he

stressed that is highly speculative.

Currently, there are no medical treatments for autism. Rather, children are

treated with intense cognitive therapies, but this approach is expensive and

controversial.