Autism Now: Dr. Irva Hertz-Piccotto Extended Interview
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ROBERT MACNEIL: The prevalence figures for autism have risen dramatically over the last decade. Do you think that it is a condition that is still growing or increasing?
DR. IRVA HERTZ-PICCOTTO: Well, the rates are continuing to rise. And those are the rates of diagnosis. Whether the actual rates of autism are still rising or whether it is a result of artifacts that have to do with the way we ascertain and the way we diagnose is something that is very difficult to disentangle.
And the research that we did — looking at data from the state of California showed that between 1990 and 2002, if we looked at children born during those years, there was a steady rise of about 15 percent per year of diagnoses of autism. Now, those data come from– a database that is put together by the California Department of Developmental Services.
And what that department does is coordinate services. So it’s not really designed for epidemiological purposes. It’s not designed to track the changes over time. It’s designed to say whether the needs within the state in terms of services that we need to provide. And it’s based on families coming to a series of regional centers that cover the whole state. So it’s not an active surveillance system. And what I mean by an active surveillance system is where the state, for instance, would go out to try to find all the cases. That’s been done in some places, but that’s not what’s actually being done in California. That’s not the way the California system works.
ROBERT MACNEIL: The CDC figures last year put the incidence, prevalence, on average at one child in 110. When the new figures come out, sort of on these two yearly cycles, would you expect that to be higher?
DR. HERTZ-PICCOTTO: Well, if the trend is continuing we would expect that to be higher. Meaning, one in less than 110. And, again, even in those data it’s hard to tell how much of it has to do with diagnosis in the eyes of people today seeing children, what would they have seen ten years ago these same people if they had today’s knowledge and today’s awareness.
They do have a much more active system than the California system. So I think those data are probably more complete than what we see in California because they go through school records as well as medical records actively trying to find children who would meet the criteria. Whether or not they actually got the diagnosis of autism, but are the behaviors — the systems evident from notes that are made in school and medical records.
ROBERT MACNEIL: Is the feeling in people like you, who are so — absorbed in this, that it is still rising?
DR. HERTZ-PICCOTTO: Well, as a scientist I have to be cautious about what I say. We were not able to explain all of the rise between 1990 births and 2000 births — 2002 births from better diagnosis, younger age at diagnosis — we looked at three things.
The inclusion of milder cases and the change in the criteria, the actual definition of autism using the diagnostic and statistical manual four, DSM four, which is the way that we characterize mental health and developmental conditions in this country.
So in 1993, there was a change in the definitions. And so with that change came inclusion of a somewhat broader set of symptoms. Now, that accounted for some of the increase. Out of a 600 percent increase that we saw, between the 1990 births and the 2002 births, that explained about 120 percent.
Then we found that younger age at diagnosis and inclusion just in terms of the diagnostic — being a little bit more liberal with the definition — also accounted for some greater, other percent as well, adding up to another 80 percent.
So we were able to explain about 200 percent out of the 600 percent. Now, we didn’t account for all possible factors outside of the true rise. So maybe more of it can be explained through, for example, diagnostic substitution. Maybe they were children who were being given a different diagnosis and then later it was realized and today.
ROBERT MACNEIL: Like mental retardation, for example, now being on the low end of the autism spectrum.
DR. HERTZ-PICCOTTO: Right. For the children who are very low-functioning.
ROBERT MACNEIL: Low functioning.
DR. HERTZ-PICCOTTO: Maybe the repetitive behavior aspect would have just been attributed to, they just don’t have very high cognitive intellectual development. So at this point we really can’t say. There is a group that did look at the diagnostic substitution explanation. They thought that maybe explained a quarter to a third. So out of our 600 percent maybe we can explain half to two thirds. But that still leaves another 200 percent rise that’s not explained.
ROBERT MACNEIL: How do you explain that?
DR. HERTZ-PICCOTTO: I don’t think we know at this point in time. But environmental factors are probably playing a role in a lot of cases of autism. And may have played a role all along that, again, we weren’t diagnosing all of those kids correctly, we were misdiagnosing, maybe even missing some of them.
But, in addition to that, there has probably been an environmental contribution for a long time. We, in fact, know that some of the potential environmental causes do include, for example, infectious agents. And, in the 1970s, there were several papers documenting, after an epidemic of rubella, which is German measles, that there was a very high incidence of autism in children who were congenitally exposed. Whose mothers had rubella during pregnancy. We’re talking 50 to 100 fold higher than the background levels of autism at that time. So out of a series of about 240 cases there were maybe ten to 20 who’ve had autism in that group.
ROBERT MACNEIL: Do you believe that there is something out there that causes now may be causing autism that didn’t exist before in the environment?
DR. HERTZ-PICCOTTO: I suspect that there are more than one such factors.
ROBERT MACNEIL: Something.
DR. HERTZ-PICCOTTO: Such as things that are in our environment. First of all, I think the idea of looking for a single cause of autism is really misdirected. And I get e-mails all the time where somebody says, “I’ve got it. I know what’s causing autism. I know what’s causing the rise in autism.”
And immediately I become very skeptical because I think this is very much a multi-factorial phenomenon. Including susceptibility genes that may interact with environmental factors, and environmental factors could disrupt development at multiple stages along the way.
So there could be factors operating very early — around the time of conception, for example. There could be factors operating during the development of the brain which actually goes on for quite a long time. It doesn’t get finalized as a fully functioning brain, as an adult brain, for a long time.
And there are structural and functional aspects that continue post-prenatal and postnatally. Myelination, for instance, which is the sheath that protects the neurons, doesn’t get fully developed until the second year post-natally.
So the brain is vulnerable through quite a period of time. And there are many factors. Chemical factors, nutritional factors, microbiological factors, physical factors like radiation and ultrasound. That could be — operating and they didn’t have to have been absence in the past, they merely had to have been present at a lower level or a lower prevalence.
ROBERT MACNEIL: Do you have candidate factors for those factors that may be fresh in the environment?
DR. HERTZ-PICCOTTO: I have a lot of candidate factors, actually. And they include nutritional factors, infectious agents, chemicals in our environment, including chemicals in the household products that we use every day. There are a variety of factors that could be influencing development.
And they may play a role at different points in development. Likely, they interact with genetic susceptibilities as well so that some people may be more susceptible to pesticides. Some people may be more susceptible to nutritional deficiencies. And multiple factors may operate around the time of conception– during brain development– which goes on for quite a long period of time. Not just prenatally but post-natally.
There may be vulnerable periods for certain kinds of factors, where critical processes are happening in brain development and certain chemicals or infectious agents may operate at different time points. But I think multiple factors contribute, not just across the population, but within any one individual. So when I say that I think autism is multi- factorial in its causation, I think that applies to even at the individual level so that it might take two or three susceptibility genes combined with two or three environmental factors at critical junctures. ‘
ROBERT MACNEIL: Which might explain why individuals with autism are so different, even though they share some obvious symptoms.
DR. HERTZ-PICCOTTO: Exactly. And whether we’ll ever be able to map one to one, these kinds of environmental factors tend to produce this kind of phenotype, these kinds of characteristic behaviors — it may never map one to one like that, but it does suggest that there is a lot of heterogeneity in terms of how you can arrive at this syndrome that’s defined behaviorally, but may have all kinds of physiologic and biochemical elements that contribute to those behaviors.
ROBERT MACNEIL: What is the specific focus of your research at the moment?
DR. HERTZ-PICCOTTO: Well, we’re looking at a lot of factors, actually. We have a paper that will be coming out, I can’t reveal the findings because it’s embargoed until actual publication, but we have some very interesting findings that pertain to nutritional factors.
And then we are working on several manuscripts right now pertaining to everything from household products and pesticides to factors in pregnancy and obstetric kinds of factors. There’s a lot of things in the pipeline right now. If you come back in a year, I’ll probably be able to talk more explicitly about what some of them are.
ROBERT MACNEIL: I see. Do you think autism is getting the research funding it deserves as compared to other medical conditions?
DR. HERTZ-PICCOTTO: Well, I haven’t done the economic analysis. Certainly there’s been an influx of more research dollars in recent years. Most of that money has gone for either the behavioral research, some of which is very helpful for developing the appropriate treatments. A lot of it has also gone for the genetics of autism.
And I absolutely agree that genetics plays an important role in autism. But I think that the funding has been a bit skewed with much more funding going for the genetics than the environmental factors. And you know, the best estimates are that it’s about 20 to one right now and I’d be happy with 50/50 to really get this going.
ROBERT MACNEIL: Do you think that part of the skewing was a reluctance of whoever funded it, defund environmental research because of the popular pre-occupation with the vaccine issue? That it scared people off?
DR. HERTZ-PICCOTTO: Well, I think I encountered resistance when I brought up the word environment and I was very surprised to find that colleagues in the field of autism immediately equated environment with vaccines. So that may well have played some role.
I think there’s also a lot of excitement about technology and molecular biology has brought a lot of recent developments in terms of how we look at genes and how many genes we can do at what price with what kinds of new technological developments we have. So often the big machines get money at national institutions of health. And those of us who are doing a little bit more of the dirty kinds of work don’t necessarily get it as much of the research dollars.
ROBERT MACNEIL: Do you feel that the prevalence figures, I’m speaking politically now, need to keep going up to keep the sense of public urgency and the political attention and so on that leads to better funding, better public support?
DR. HERTZ-PICCOTTO: Well, I don’t want to be the one saying the rates should continue going up. We all want the rates to go down.
ROBERT MACNEIL: Of course not.
DR. HERTZ-PICCOTTO: How we can get them to go down I think is really the challenge at this point in time because without knowing what the causes are, it’s really hard to see how we’re going to start seeing it go down. Maybe we’ll see it plateau at some point if it’s to the extent that the rise has been due to better ascertainment at some point we should be having complete ascertainment and it should level off.
I haven’t seen signs of that yet so at this point, our best guess is it’s still going up and we’ll be hearing I’m sure from CDC what the latest figures are. With regard to the environmental factors, one of the papers we did publish recently showed that families living closer to freeways had higher rates of autism. Now, the proximity to the freeways, of course, correlates very highly with exposures to air pollutants that are part of motor vehicle exhaust.
Some people have said, well, but that’s been around for a long time. We’ve known about air pollution. This isn’t new. Well, that’s true. I don’t think all the factors that contribute to autism have to be rising. Because if autism has been with us and we haven’t been detecting all of the cases there’s likely causes that have been around for a long time and causes that have been rising recently. So I don’t think we can dismiss the possibility that air pollution is contributing to autism.
CAREN ZUCKER, PRODUCER: To the people who would say there is no increase it’s just, the factors that you stated earlier. What would you say to someone who says, “Absolutely, it’s just that we’re counting better and there’s always been this many people with autism.”
DR. HERTZ-PICCOTTO: There do seem to be people who believe that the rates of autism aren’t going up. What I’ve observed is that those people are often the people who are very focused on the genetics. And I can understand part of that. There’s a lot of excitement about the technology being able to basically map the entire genome of an individual, cheaply and rather quickly.
It is true that autism has a strong genetic component. And when we look at monozygotic twins that come from, the same fertilized egg, the concordance rates where both twins will have the diagnosis rather than just one, are high. They’re 60 to 90 percent is the estimate.
I think the mistaken conclusion that people have drawn from that is that that only leaves 10 to 40 percent that can be environment. But the problem is that it isn’t a case is just genetic or a case is just environmental. Many cases, as I said before, are the result of both, meaning an interaction of genes with environment.
The genes may lay the basis. As some people would say, they load the gun, but somebody’s gotta pull the trigger, and that those are the environmental factors. Not my favorite metaphor, but it’s the only one that’s been used.