Autism Diagnosed With a Fifteen Minute Brain Scan

kkleiner writes "A new technique developed at King's College London uses a fifteen minute MRI scan to diagnose autism spectrum disorder (ASD). The scan is used to analyze the structure of grey matter in the brain, and tests have shown that it can identify individuals already diagnosed with autism with 90% accuracy. The research could change the way that autism is diagnosed – including screening children for the disorder at a young age."

Comments

Re:Unacceptable false positive rate

[Ihlosi]

You're still putting 10 families through the stress of comprehensive testing for autism for no reason for every 1 family whose child actually has the condition.

MRIs are expensive, and autism-like behavior is obvious enough that you can narrow down the group of people you're going to test significiantly before you start testing. Also, for families with one or more kids with behavioral disorders, a 15-minute test usually doesn't qualify as "stress", at least not compared to all the other crap they have to go through.

Much higher

[Mirey]

its actually much higher than that. What you're quoting is that 1 in 10 people with autism and given a false negative. Its actually much worse. Out of 10,000 children, 1980 would be found positive, out of which only 90 would have the disease. So only about 5% of people who tested postive would actually be autistic. It says this in TFA.

I'm not exactly impressed...

[Anubis IV]

They're trumpeting this 90% statistic, but what about the false positive rate? Contrary to standard /. procedure (I know, I know, I'm sorry), I decided to read TFA for an answer, and this is what I found out.

Let’s think of 10,000 children. Of these 100 (1%) will have autism, 90 of these 100 would have a positive test, 10 are missed as they have a negative test: there’s the 90% reported accuracy by the media.

But what about the 9,900 who don’t have the disease? 7,920 of these will test negative (the specificity in the Ecker paper is 80%). But, the real worry though, is the numbers without the disease who test positive. This will be substantial: 1,980 of the 9,900 without the disease. This is what happens at very low prevalences, the numbers falsely misdiagnosed rockets. Alarmingly, of the 2,070 with a positive test, only 90 will have the disease, which is roughly 4.5%.

So it only has a 4.5% true positive rate. Great.

Re:I'm not exactly impressed...

[Bazman]

Yep, but that might make it a useful *screening* tool rather than a *testing* tool. You'd then go do proper (ie more specific) tests.

I can get a 99% correct diagnosis rate on autism just by going "not autistic" every time.

I've read the original paper, and its based on a sample of 20 normal and 20 autistic people, I might have another read to see if they've done multiple tests and only picked the significant one. Search for the poster about fMRI responses in a dead salmon for more info...

Re:I'm not exactly impressed...

[Thanshin]

So it only has a 4.5% true positive rate. Great

Indeed, it's significantly worse than my (99% true rate) autism diagnosing rock that evaporates if an autistic child holds it.

And my rock takes much less than 15 minutes.

Re:I'm not exactly impressed...

[Shrike82]

While I understand that your post was humerous, I feel somehow compelled to point out that you'd have a 0% true positive rate with your rock, a 0% false positive rate, a 99% true negative rate and a 1% false negative rate.

Hmm, I think I might be autistic myself judging by my inability to resist making this post.

Re:I'm not exactly impressed...

[Thanshin]

Hmm, I think I might be autistic myself judging by my inability to resist making this post.

Here, hold this rock for a second.

Re:Unacceptable false positive rate

[txoof]

As you said, this will just be used for further testing. Treatment for autism is very similar for other behavioral abnormalities, so not much will change for the families. If a child has already been singled out for further testing by their teachers/counselors/doctors/family, this will just be another in a set of tests to help further treatment. A child with EBD or Autism receives much of the same interventions at school and home. The interventions are extremely specific to each child; knowing that this child may be autistic gives parents, teachers and doctors a more focused approach to treatment. It directs which bag-of-tricks to start working from. Fortunately, if the child is not actually autistic, but has say Pervasive Development Disorder (PDD), many of the same interventions such as remedial communication skills and socialization skills can be used.

It's not like this test puts a kid into a box with only one possible medication or treatment is offered. Each child's treatment is developed with the parents, teachers and other professionals. Some kids need headphones to walk though the cafeteria, some kids need a special squeeze ball, some kids need slow subtle introductions to complex social situations with highly scripted encounters to help them understand what is going on. This is true for the whole spectrum of EBD/autism disorders. Being able to scan a kid that might be autistic just gives everyone a much better starting place. They have a greater chance of successful treatment if they know which bag to start with rather than just grasping at straws.

Re:Autism, is it really a disease?

[rve]

While people who suffer at the extreme ends of the autistic spectrum would have difficulty maintaining a society, some of the more moderate autistic individuals are leaders in engineering, technology, and science.

You could say the same about cancer. Some leaders in engineering, technology, and science have cancer. That doesn't mean cancer may not really be a disease or that a neoplasm may simply be the next step in our evolution.

It has become fashionable among nerds to identify with Dustin Hoffman's portrayal of Rainman to the point anyone who is even remotely socially awkward or left brain oriented to be called autistic, followed by the implication that autism fills an important role in society. The reality is somewhat different. With a few famous exceptions, patients tend to have trouble taking care of themselves - many are profoundly disabled - while actual leaders in engineering, technology, and science tend to have normal mental health. (though many of them may be assholes, but that's another story)

Is there enough Helium?

[Dunbal]

The research could change the way that autism is diagnosed - including screening children for the disorder at a young age.

      The thing about primary screening tests is that they have to give false positives, due to high sensitivity and lower specificity. It's ok if the test tells you you have HIV when actually you don't. It's NOT ok if it doesn't tell you you have it when you do. The other thing about primary screening tests is that they have to be cheap. This test is far from cheap and in fact consumes limited resources. In some countries there are waiting lists for MRIs.

      Perhaps this test could be used as a secondary screen, if specificity can be proven to be high enough, to screen those doubtful or borderline cases so that they can be correctly diagnosed.

Re:Is there enough Helium?

[Dunbal]

I don't understand your reasoning.

      That's because you're not a health care professional. Put your personal feelings aside for a second and look at it this way:

      I have a population that might have a disease. The symptoms of the disease are not obvious, and there's no easy way to tell who has it and who doesn't.

      I have a very specific genetic test (Western Blot) that can tell me if that person's blood contains viral DNA. The test is specific because I am identifying DNA from the virus in question. You can't get more specific than that. However this test does have the possibility of false negatives - the person may have the virus, but I might have gotten a sample that for some reason contains no viral particles. Or the virus may be latent, living in T-cells in the bone marrow right now and not circulating in peripheral blood. NOT finding the DNA does not mean you don't have the virus. Finding the DNA confirms that indeed you have the virus. Also, this test costs a lot of money, and uses a lot of resources - less nowadays than 10 years ago, but still.

      On the other hand, I have a very sensitive test, the Enzyme Linked ImmunoSorbent Assay. This test identifies antibodies to the HIV virus down to very very dilute concentrations. It is extremely cheap. It can be done everywhere there's a centrifuge to obtain plasma from a blood sample. However because it identifies antibodies and not the virus itself, it is not a specific test. It's possible that a person have HIV antibodies without having the virus - because they were exposed to it enough to trigger an immune response, but never got an infection (the virus never "took hold"), or by some freak of nature, they have a SIMILAR antibody to something else that is reacting to the test. So thus the false positives - the test says you have it when really you don't.

      What we doctors do is we tend to SCREEN the population with the simple, inexpensive test first. Why? Because it's simple and inexpensive. That gives us a new population that absolutely captures all the diseased people, and also contains some false positives. We tell people that there may be a problem but they shouldn't worry about it just yet - but we need to run another test to be sure. YOU DO NOT TREAT PEOPLE BASED ON A PRIMARY SCREEN!

      To this new population you administer the second, expensive, SPECIFIC test. This lets you "weed out" those people who are false positives. You tell them congratulations, everything is ok and they probably shouldn't worry. You just keep an eye on them for a year or so to make sure they were indeed false positives and weren't people who for some reason gave a false negative on the second test. Maybe you repeat the test the year after just to be safe. And the rest, the real positives, end up with the diagnosis and the treatment.

      So what happens is you administer the expensive test to fewer people, saving time and resources, without letting anyone with the disease slip through the cracks. In the case of autism, presumably the primary screen would be the clinical signs - does the child exhibit autistic behavior and fit the criteria? IF that is the case, or IF the physician isn't sure, then the secondary screen (MRI) would be performed. My doubts are about the specificity of the MRI - will it show false positives - people with MRI changes that don't have autism? If so, then it's possible people will be misdiagnosed and that's a no-no.

      As for social stigma, uh, that's what doctor-patient confidentiality is about. I certainly won't tell anyone. It's not my problem if I tell you "listen we ran this test and you tested positive for HIV. It doesn't mean you have HIV though, we need to do a different test to be sure" and then you run around telling everyone you have HIV. I find that patients usually understand things when you explain them properly.

Re:Unacceptable false positive rate

[mangu]

I probably have Asperger's too, because I'm an analyzer and often come to the conclusion that some widely accepted behaviour is often rather stupid.

Then I must have Asperger's too. I don't go to church, I don't watch sports on TV, I believe that men went to the moon, I believe that heavy use of fossil fuels is causing global warming, and I believe fluor is good for your teeth.

Maybe I was vaccinated when I was a kid.

Real Humiliation

[Ukab the Great]

Therapy's not humiliating. Hell, OT's kinda fun.

Real humiliation is when you're growing up and all the interactions with your peers blow up in your face due to your mind-blindless and inability to read body language or understand personal space, and your classmates ostracize you because they think you're weird, and you don't know what's going wrong. And since there's nothing you know of (because your'e undiagnosed) that differentiates you from your peers or explains why this is happening, you conclude you're getting ostracized because you're some doofy, idiotic, bad person. That, my friend, is real humiliation.

Re:Unacceptable false positive rate

[aastanna]

Sounds like every episode of House.

Base rate fallacy

[martyros]

Not really -- the problem is with the base rate fallacy. Suppose that there's a test that will tell you whether or not you have a disease with 99% accuracy: if you have it, you're 99% likely to test positive; if you don't have it, you're 99% likely to test negative.

Now, you get a test and it's positive. What's your probability of having the disease?

The answer is, "There's not enough information to answer the question." The missing piece of information is the "base rate".

Suppose that 50% of the people have the disease. Then in testing 1 million people, 500K will have the disease, of which 495K will come back positive (true positive), and 5K the test will come back negative (false negatives). 500K will not have the disease, of which 495k will come back negative (true negative), and 5k will come back positive (false positive). If the test came back positive, you're either a true positive or a false positive. Since there are 500K positives, and 495K of those are true positives, your chances of having the disease are 99%.

Suppose instead that 1% of people have the disease. Then in testing 1 million people, 990K will not have the disease, and 10K will have it. Of the 990K, 980K will come back negative (true negative) and 10K will come back positive (false positive). Of the 10K, 9900 will come back positive (true positive), and 100 will come back negative (false negative). There are 19,900 who tested positive, of which only 9900 (less than half) actually have the disease. So if you tested positive, your chances are about 50%.

So even if the test itself is very accurate (and I think 99% is pretty accurate), if the base rate is low enough (and in autism I believe it's still less than 1%), a positive reading may not be conclusive. You'd have to correlate it with other symptoms to make sure.

Re:Autism, is it really a disease?

[SETIGuy]

With Autism being so prevalent in humans you do have to wonder if it is really a disease or mistake, or perhaps either a previous evolutionary step or our next evolutionary step.

This point gets raised on Slashdot quite often, and it represents in incredible misunderstanding of evolution. Evolution doesn't have steps and doesn't progress in an easily identifiable direction. Genetic features aren't mistakes. They just are. And they are either beneficial in some way or they are not. If there are specific genes responsible for autism and they always cause autism, they would need to spread to a very large fraction of the population to be indicative of evolutionary change. They would also need to be beneficial to reproductive success.

Now it's possible that some of the genes that cause autism are beneficial, but that having too many of them causes autism. It would be difficult to go from that state to an entirely autistic species. I don't see highly autistic individuals finding autistic mates and having large families. Even if they did, the children might not be autistic. We don't understand the genetic and environmental combinations required yet.

If you've had any contact with highly autistic people, you'll know that an autistic species wouldn't survive for long. Fully autistic people (not the ones on slashdot who claim to be autistic but are just lacking in social skills) do not have the skill set to survive alone. Or to recognize that another individual might need help. Or to recognize that another individual has thoughts, emotions, or a different point of view. The savant skills that some autistic people have are rare. Autistic people who can't count past 10 outnumber the "living calculators" by factors of a thousand.

Of couse, Autism isn't "good" or "bad." It just is. But it is hard on families. If a way is ever found to prevent it, I think most people would be happy about it.