A recent study has found that the familial link in autism was almost twice as high as had previously been thought:
MONDAY, Aug. 15 (HealthDay News) — Younger siblings of a child with an autism spectrum disorder have a nearly one in five chance of being diagnosed with autism, much higher than previous estimates, a new study finds.
The researchers found that 18.7 percent of children who had a sibling with autism also went on to receive an autism diagnosis by their third birthday, and the risk was significantly higher for boys and those with more than one autistic sibling.
“Those of us working in the field knew the rate was a lot higher than the previously published rate, but I don’t think we expected it to be this high, ” said lead study author Sally Ozonoff, a professor and vice chair for research in the department of psychiatry and behavioral sciences at the University of California Davis Medical Center’s MIND Institute.
Previous research has estimated that about 3 percent to 10 percent of younger siblings of kids with an autism spectrum disorder (ASD) will also be diagnosed with the condition.
While I’m on the subject I wanted to recommend a documentary on autism and people with autism that my wife and I just saw: Loving Lampposts. I found it engaging and very balanced. It raises a lot of good questions. It’s available streaming via Netflix.
Update
I haven’t read the study myself yet but I have heard some secondhand reports that the study found that the fraternal twin of a child with autism is half again as likely as a sibling to develop or exhibit autism and that identical twins are no more likely both to have autism than fraternal twins. If that’s the case, it’s an important finding, suggesting both genetic and prenatal environmental issues play a part.
“to receive an autism diagnosis by their third birthday” seems a little ambitious; I wonder if they are catching false positives. I understand that the precautionary principle doesn’t mind over-diagnosis since the benefits of early intervention are clear. But I wonder if advances in testing for treatment purposes might not be impacting our ability to analyze causation theories.
I’m skeptical that autism has a single cause or is even a single condition. I suspect it’s multifactorial resulting in multiple different conditions for which similar interventions may be effective. Consequently, I’m less interested in determining causation than I am in finding the most effective ways of helping the people with autism be as self-sufficient and productive as possible.
In the case of this particular finding it will be interesting to see if they can isolate the reasons further to heredity, environment, behavioral, or just plain vigilance.
If the researchers were using traditional surveys that relied upon interviews with parents; one can easily imagine the parental vigilance might lead to more diagnosis. I’m told that newer testing based upon watching the child’s eye movement during films is promising — it might dispense with some of the subjectivity.
BTW/ here is a pediatrician’s take on the problems of early diagnosis and false positives, along with spirited accounts in the commentary:
http://seattlemamadoc.seattlechildrens.org/autism-screening-at-1-year-check-up/
I should precede my next remark by saying that I think the innoculation theory of autism is not only fraudulent claptrap, it’s cruel. However…IMO the strongest evidence for it is the many reports by trained observers that they went into the physicians office (for the immunization) with one kid and came out with another.
The conventional explanation for these reports is developmental age, i.e. autism is present from birth but not apparent until a child reaches a certain level of development which the child reaches, coincidentally, at the age that most innoculations are administered.
There are any number of possible alternative explanations that I’ve never seen addressed, e.g. the psychological (or even physical) trauma of the innoculation experience, coming into contact with a pathogen in the waiting room (or the physician’s examining room) to which the child is particularly susceptible.
This is an interest of mine, having an Aspie kid. I also knew Offitt in training. The vaccine theory is total nonsense. Wakefield’s research, financed by malpractice lawyers, was all lies. There are huge epidemiological studies not showing any change after they removed Thimerasol and changed vaccination patterns. In my field, we picked up changes in incidence at 1 in 10,000 for complications when they changed a certain drug. There is zero basis for the vaccine theory.
There is a certain amount of over diagnosis anytime you have an “in” diagnosis, but when you have kids who are really on the autistic spectrum, it is pretty easy to tell very early. When your kid does not interact with other kids or even look at other people, it is noticeable.
Steve
As a special education teacher who has worked with many students at various places on the autism spectrum I have no great insights. I do know identifying someone of school age as on the spectrum is very subjective. I currently work with Somali students who have an unusually high rate of Autism in their population. I also may a very low functioning brother of one of my high functioning ASD students on my case load this year. I probably should gear up for school by adjusting my reading habits to include Autism in the mix.
To clarify my earlier remark I’m not voicing a concern about over diagnosis for it’s own sake; I just think its particularly problematic in the mental health field in terms of statistical analysis. The testing being performed these days is motivated towards casting a wide net to catch potential issues early and benefit from early treatment. That may work at cross-purposes to the task of research.
There is an example in the comment section of my link: there appears to be a child who had a non-spectrum developmental problem who benefited from being diagnosed as potentially autistic. From a public health standpoint it sounds like a success, but seems like it would pose epistemological problems for research.
A belated thanks for this post. I watched “Loving Lampposts” this week.
An autistic child is coming within my orbit. I have no previous experience with any.