Saturday, December 09, 2006

Autism & Familiy Ties

While fears of vaccines and thimerosal as potential causes of autism, without substantial scientific support for those fears, have dominated media coverage scientists have been studying biological and genetic factors that might influence the development of autism. In sometimes light hearted and totally unscientific discussion with other parent autism advocates I have remarked on apparent "autistic tendencies" of some parents including yours truly. A group of studies have focussed on family members of persons with autism and are producing some interesting results. These studies apparently show that parents and siblings of autistic children sometimes share some of the anatomical and behavioral anomalies characteristic of autism, even though they themselves do not have the disorder.

Ped Med: Studies eye autistic kids' kin

SAN FRANCISCO, Dec. 8 (UPI) -- A number of studies have shown parents and siblings of autistic children sometimes share some of the anatomical and behavioral anomalies characteristic of autism, even though they themselves do not have the disorder.

The studies were carried out to circumvent the difficulties inherent in investigations of brain and cognitive development in autistic children, many of whom have limited communication skills, among other challenges, researchers said.

In one investigation, scientists at the University of Colorado, Colorado State University and the University of Denver pored over three-dimensional brain images of the children's kindred for signs of heritable abnormalities.

In comparing the scans of 40 parents with autistic offspring and 40 without, they found size differences between the two groups in a multitude of regions, each of which regulates behaviors that are affected in autism, the authors said.

In the autistic children's kin, they reported observing:

-- A shrunken cerebellum, the coordinator of motion and regulator of speech, learning, emotions, attention and other cognitive thinking;

-- A shriveled prefrontal cortex, also referred to as the "theory of mind area" because of its pivotal role in interpreting intentions, motivations and feelings of other people;

-- An oversized motor cortex, the controller of voluntary movement;

-- A bloated basal ganglia, a center for planning and imitating motion that also is associated with compulsive and ritualistic behaviors, and

-- An undersized somatosensory cortex, a site critical to comprehending facial expressions and other social cues.

The team is planning to confirm the findings in studies of twins.

At the University of Wisconsin-Madison, investigators used advanced imaging and eye-tracking technologies to peek at ocular activity and measure brain structures in nine boys with autism, their nine non-autistic brothers and nine unrelated healthy youngsters.

They said they found the sibling pairs shared the autistic proclivity to avoid eye contact with strangers, friends and even family members.

In addition, the researchers said, the boys had an abnormally small amygdala, an almond-shaped, multi-task area that holds the key to reading facial expressions and experiencing fear at social situations.

None of these features appeared in the "control" group of non-autistic boys with non-autistic relatives, the study authors said.

Because the deficits observed in the typically developing brothers of autistic children did not result in any noticeable symptoms, the researchers reasoned other brain areas must be compensating for the shortfalls. That suggests autism touches multiple brain systems to make itself known, the investigators said.

Parental genes may affect a baby's growth in other unforeseen ways, scientists said.

In one surprising finding, investigators from Wake Forest University Baptist Medical Center in Winston-Salem, N.C., noted the nutritional composition of a woman's breast milk -- which has a bearing on the nursing infant's development -- may depend not only on what she eats but also on what she's inherited.

In the first study to show a genetic effect on human lactation, the researchers discovered having a certain variant of a gene -- which some one-third of the U.S. population does -- can boost by 40 percent the amount of a needed nutrient that enters a mother's breast milk, the team reported.

A shortage of the substance -- a type of omega-3 fat called decosahexaenoic acid, or DHA, found mainly in cold-water fish such as tuna, salmon and mackerel -- has been implicated in autism, attention-deficit/hyperactivity disorder, learning disabilities and other developmental disorders.

(Note: In this multi-part installment, based on dozens of reports, conferences and interviews, Ped Med is keeping an eye on autism, taking a backward glance at its history and surrounding controversies, facing facts revealed by research and looking forward to treatment enhancements and expansions. Wasowicz is the author of the forthcoming book, "Suffer the Child: How the American Healthcare System Is Failing Our Future," to be published by Capital Books.)


Anonymous said...

I suspect [from my own personal experience i.e. biased ] that this is essentially true. I don't know if you've come across it, but there is a book by Charlotte Moore called George and Sam [a Brit writer I'm afraid] that my mother gave to me. It was the first 'case' I came across where someone has more than one autistic child. [now I know that there are zillions] but that was a while back.

She identifies little quirks in various family members. It's quite disconcerting - but we're all used to disconcerting by now! Right?
Best wishes

Ian Parker said...

Hi Harold,

I believe what you are referring to is the broader autism phenotype (BAP for short).

Something you may find interesting that I wrote here links ASD and the BAP to an underlying brain structure, as per the findings of Dr Casanova.