Yesterday I found out the cause of my child’s autism. I read an article that positively stated in the headline that lack of Vitamin D in pregnant women is linked to autism. Great, I thought. So if I want to make sure my next child does not have special needs and I don’t have to spend hundreds of thousands of dollars on therapy, I just have to take some supplements. Score. Easy.
Well, once I read the article that’s not quite what it said. What they meant with that rather sensational headline, is that women that have a serious lack of Vitamin D are more likely to have children that exhibit autistic traits by the age of 5. For a slightly more detailed overview of it, you can find a good article on it here
Now, I like studies. I have always liked them. Especially large scale ones like the one they were talking about, done at the Queensland Brain Institute. They analysed 4,000 blood samples from pregnant women and their children. From this they discovered that those that were deficient in vitamin D had ‘significantly higher’ scores on autism scales than those who had adequate vitamin D levels. Apparently the most important time to pop those vitamin D supplements is in mid-gestation and at the time of birth. Take them into that delivery room ladies! (Just to be clear, I’m only half joking here. I fully intend to take my vitamin D supplements while pregnant, for many reasons).
This is all great and good. But there are other interesting statistics too. For example, one third of all Australians have a vitamin D deficiency. In Australia people! The land of sunshine! I hate to think what this means for our UK readers! However the proportion of children that have autism is considerably lower than one third. It’s more like one in fifty.
A past sensational article I read told me that not taking ante-natal vitamins was linked to autism. Another one that linked it to maternal and or paternal age. Plus something about vaguely worded ‘environmental factors’ and another thing about cousins or having kids too close together in age. Ooh there was one about sex positions that I found fascinating. How did they test that one? I want to be on that research team…
Of course I took my pre-natal vitamins religiously (and they included vitamin D), had my son aged 25, my husband was 26 and I’m not entirely sure what the sexual position was at the time. It was our honeymoon, so, you know…However we are supremely unrelated so we’re off the hook for that reason. Actually really not related at all. His family is Catholic and from Lebanon and mine is Jewish and from Russia. Almost every other couple in history is more related than we are.
In reality we all know that refrigerator mothers that force their kids to have vaccines cause autism. Also it can be cured with camel’s milk. My naturopath told me so last week while selling it to me for $30 a bottle.
Professor Andrew Whitehouse (who if you follow my Facebook page you know is my fount of all wisdom) dared to put this into perspective. He said that autism is linked to hundreds of different mechanisms that may or may not lead to this condition. He also said something about seeing this finding replicated before jumping to conclusions, which is just inconsiderate really. We all like jumping to conclusions. For some of us it’s the only kind of jumping we do all day. For more technical wisdom from Professor Andrew Whitehouse on the causes of autism, have a look at this article, otherwise – I’m going to have a crack at explaining as much of it as I can.
Brain Development and Autism
We do know some things about autism, although way less than the people that write articles for online newspapers. There might in fact be several causes including genetics and brain development. It is known that the brain develops differently in children with autism.
Their brain tends to grow too fast during early childhood, especially during the first three years of life. And the brains of babies with ASD appear to have more cells than they need, as well as bad connections between the cells.
From what I understand, brain connections grow rather quickly at an early age, rather like plants and weeds in a garden. The brain is like a gardener in that it ‘prunes’ the connections that aren’t necessary to make space for the important ones. Important ones being connections that help with everyday actions like walking, talking, and interacting with others. Apparently in children with ASD this pruning isn’t done as well so information gets lost or gets sent through the wrong connections.
Genetics and ASD
The best way to tell if something is genetic is to study it in twins. Identical twins share their DNA – it is identical. Non identical twins share about half their DNA. Both types of twins also share the same environment so any differences in incidence of autism between the two sets will to a great extent be due to genetics. There are debates about this but broadly speaking, the environment is very similar.
The current estimate is that if one identical twin has autism, the other has about a 50-80% chance of also having autism. And it’s much closer to 80. Always remembering that even if they don’t have autism they are almost certain to have many of the same signs and behaviours. If you add this in an identical twin has a nearly 100% chance of either having autism, or many of the same behaviours. Although importantly, it is not 100%. But with non-identical twins, who only share half their DNA the chance is somewhere around 30%.
For siblings the chances are about 5-20%. In terms of boys and girls, this may mean that a boy will veer more towards the 20% chance and a girl will have more of a 5% chance. There is also about an equal chance that a non-identical twin or sibling will display many of the same signs of autism without a definite diagnosis. And of course the exact statistics can be very difficult to pin down, because of how under-diagnosed little girls are.
More Twins Studies
To make it clear twins are more likely to develop autism than ordinary siblings. And identical twins are more likely to have the same ‘level’ of autism than non-identical twins. A study also concluded that high levels of autism symptoms are genetic in origin. Less severe symptoms are not as likely to be inherited. To read more about this study, have a look here.
There is even a fascinating study that shows that having children too close together (conceived within twelve months of each other) or too far apart (conceived more than 6 years apart) doubles or even triples their risk of having autism as compared to siblings conceived 3-4 years apart. This would suggest that the mother’s ‘nutritional status’ might be a factor in autism so that twins or siblings conceived very close together ‘deplete’ maternal resources more and are therefore at a higher risk. With siblings born very far apart, the parents’ infertility may be a factor and the mother may have trouble conceiving and carrying a baby to term. To read more about this study, have a look at this Time magazine article on the subject.
Apparently what can happen is that a gene can get altered during fetal development. Another possibility is that a child will inherit the genes from one or both parents. It is very common if you have a child with ASD that members of your family either have an autism diagnosis or exhibit some of the signs of ASD. You might even just have a family full of eccentric engineers who dislike change and aren’t very sociable. Apparently Silicon Valley is full of them.
It’s unlikely that there’s one specific gene that causes ASD. Rather, it might be that several genes combine and act together. Researchers have found many possible genes that might play a role in the development of ASD.
Is Autism Even One Condition?
In some ways from my research and my interactions I have concluded that there is no one type of autism. Autism is a ‘name’ that is given to so many different conditions that seem to share some features but are in fact probably completely different.
Some conditions have very clear genetic or chromosomal abnormalities that can lead to autistic behaviours. Around 10-15% of individuals diagnosed with autism have abnormalities of the chromosomes, like in Down Syndrone. And apparently many of the same genetic changes occur in people that do not have autism – but if several of these genetic changes occur in the same person, in combination they have a major effect on how the brain develops.
ASD can also happen together with other genetic conditions. This is called co-morbidity, but that is a story for another article.
Every time I read about environmental causes and autism, the article always seems so positive. And I die a little inside from how awful the scientific knowledge of the person that wrote the article must be.
Environmental factors and autism are very badly known. In the real world that is, not the lala land inhabited by many ‘natural health’ bloggers. However epidemiology can be used to look at some of these factors. (Please note, I have nothing against natural health bloggers. Anything that gets us to eat our broccoli and exercise is good. Just don’t expect it to cure your cancer.)
Some things have been linked to a slightly (key word: slightly!!!) increased risk of autism. One is bacterial or viral infections in the mother during pregnancy. Others include a folic acid deficiency at the time of conception, the presence of gestational diabetes, and the use of particular anti-depressants. It should be noted that no conclusive evidence exists for any of these links. But try not to get gestational diabetes anyway.
Being an older parent, especially being a father over 50 (for once mums, it’s not our fault) also increase the risk.
Other Biological Factors
There are some studies that show that babies that are later diagnosed with autism, are exposed to higher levels of testosterone in the womb. However, again, it is certain that not all individuals with autism have been exposed to higher levels. So once more I repeat, we are only sure that we are not sure.
And what about gut problems? Between 30 and 50% of individuals with autism experience significant gastrointestinal problems, such as diarrhoea, constipation and an irritable bowel. We don’t know why gut problems are linked to autism but it is known that the complex community of microbes in the gut plays an important role in human development and is essential for healthy immune and endocrine systems, as well as the brain.
The evidence for disruptions in gut bacteria as a ‘cause’ of autism is not currently strong however. So don’t go looking for it, because there are a lot of quacks out there selling ‘gut’ solutions to parents. There is a lot of research being done in this field currently so keep a look out for it.
Autism and Regression
I think the driving force behind most crazy conspiracy theories about autism is the regression that occurs in about 25-40% of children. It usually occurs around the same time (median age of 19 months) as some vaccines and since human beings always look for an immediate cause, parents blame them for the symptoms.
There is no evidence vaccines cause autism. Research has shown that most children that have ‘regression’ (ie lose some social or verbal skills) will have atypical development long before this. It might be obvious or not to their parents but it has been there from the beginning. Some of it has been linked to a history of thyroid disease or autoimmune problems in the family. But it should be noted that even people that deliberately delay vaccinations at this stage will have the same patterns of regression at the same general age. So they pretty much put their children at risk of a horrible horrible death for no good reason at all.
Most theories around why it happens involve something about the fact that it was always there, but the brain had the capacity to ‘make up for’ some of the symptoms at an early stage. In some ways this is similar to many diseases like Parkinson’s or arthritis that might have been present for a long time before they become ‘apparent.’
Once the issues built up, or social interaction gets more complex, the brain can’t ‘make up for it’ anymore. Although it should be noted that some studies show that these children may regain the skills they lost with some therapy around the age of 3.
So what actually causes it?
According to the raising children network there is no solid evidence to show that ASD can be caused by anything in the environment, like diet (either during pregnancy or once a child is born) or exposure to certain toxins.
The key thing to take away here: external factors might trigger ASD in a child who is already genetically prone to developing the condition.
There is a genetic predisposition in a child. A very strong one. And possibly some of the things that happen to the mother or the fetus might add slightly to the odds or take away from them, but overall none of them seem to make any kind of decisive difference.
There will be millions of women out there with vitamin D deficiencies. They might be aged 45 and be smoking and taking drugs. I don’t recommend it but it happens. Yet their child will likely not have autism if the genetic predisposition is not there.
So no, you did not ‘cause’ your child’s autism. Phew, we can all breathe freely now.
Does it even matter?
I get a lot of parents that tell me, that they don’t care what caused their child’s autism. They just want services and support that will help them cope with life. Well, this is definitely a good point and I agree to a very great extent. Better services will help my child way more than knowing the cause.
I personally do care. Partially I care because if it can be diagnosed really early, like in the womb, then early intervention can start really early.
Another reason I care is purely intellectual. I find autism fascinating and anything to do with it. I think I would find it nearly as interesting even if I weren’t touched by it so personally. It is a field so full of sacrifice, effort, and love. So many amazing people are involved – both the ones on the spectrum, their parents, and the educators.
There are many ethical issues concerned with being able to tell what causes it, of course. I won’t go into them here or this post will turn into a short novel. Knowing what causes it will allow people to possibly prevent it. Whether we as a society are ready to make that choice is unknown. As far as I am concerned the benefits of potential early detection (especially in girls, who are so under-diagnosed) outweigh the potential ethical problems. So I will continue to monitor this field. And meanwhile give my little one as many kisses as possible, because no matter what causes his autism, he is also the most kissable human being on the planet.