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David Baxter

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Perspectives on Autism "Epidemic"
Wednesday, June 13, 2007

As we've previously reported here as well as on our sister site, The Psychology of Education, the medical world and the general population have become increasingly aware of autism spectrum disorders (ASD) among us due to repeated mentions in the news and an exponential increase in diagnoses over the past decade. The question posed now: is there truly an autism epidemic? Has the disease multiplied, and do millions more now suffer from it? If so, why? Is the cause genetic, environmental, or some combintation thereof? If not, why the huge increase in numbers?

If the incidence of autism among the general population has truly grown at the same rates as its diagnoses, the trend cannot be simply genetic in nature. Such a development would imply the introduction of some basic functional change applied to millions of people in disparate locations and situations, which was then passed along to their offspring (and genetic changes tend to make themselves known over multiple generations). Most diseases are relatively easy to definitively confirm or deny with blood testing and other physical procedures. The major problem with measuring diagnostic trends and research necessary to (in)validate concerns over an autism "epidemic" is that the condition presents no biological markers. Assessment and diagnosis proceed on a purely behavioral level.

On the environmental triggers front, several high-profile pharmaceutical lawsuits (nearly 5000 in total) have been filed in recent years claiming that the presence of mercury in the common preservative thimerisol, which is used in childhood vaccines against potentially fatal diseases such as tuberculosis and whooping cough, brought about an autism diagnosis in affected children. The use of the substance in childhood vaccines ceased eight years ago, but many believe it to be responsible for ASD diagnoses in their children. No major verdict has ever fallen in the plaintiffs' favor in this sort of case, largely because none of the many related clinical studies have ever conclusively linked mercury exposure to autism diagnoses. As much as many parents want to believe that this element is the culprit and that its manufacturers, due to some form of conspiracy, will never be held accountable for the damage they caused, there is no agreed-upon link between autism and mercury. On the other hand, thimerisol's discontinuation is not a bad thing, as mercury poisoning is a very real threat.

The most reasonable explanation, supported by research and the testimony of clinical experts, is that the methods and standards we use to define autism have expanded, allowing for more children to fall within the spectrum. This more nebulous definition of the disorder may also lead to less specific treatments for kids whose conditions exist at different points along the spectrum. It may also be a good thing, as more kids will qualify for assistance and we will need to make appropriate changes in the education system in order to accomadate them. Some schools have already adapted in a largely improvisational way, attempting to help their autistic students find company with their peers. Many of their behaviors still make them difficult to deal with in traditional school settings, but as our knowledge of autism expands, more children will begin to appreciate the problems encountered by their autistic peers. Are we in the midst of an autsim "epidemic?" We have no means by which to truly answer that question. While the percentage of ADS individuals in our society is not likely to increase, the level of attention paid to them certainly will, which can only be a good thing.
 

Peanut

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was just going to make a couple of comments about the article. 1) I think it restates what is the general consensus, that the diagnosis has broadened to encompass a wider spectrum of behaviors the fall into this disorder 2) I also think the comment about it being a combination of environmental and genetic factors is true for a huge number of psychological disorders so that should really not be any big news or distinction for autism and 3) it's pretty much been established there is not enough evidence to say the vaccinations are responsible for autism, but nonetheless, since a lot of things about the disorder seem pretty mysterious it's no wonder people are leery of them and a host of other things.

One thing I've been pondering lately, why is autism not coded on axis II of the DSM? Is it because with early intervention it is possible to lose the diagnosis?
 

HA

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It is coded on Axis II, Arose. It is a developmental disorder which falls under mental retardation.
 

David Baxter

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One thing I've been pondering lately, why is autism not coded on axis II of the DSM? Is it because with early intervention it is possible to lose the diagnosis?

No. It's because Axis II is primarily reserved for disorders of personality rather than mental illnesses.

http://www.behavenet.com/capsules/diagnostic/axis2.htm

Axis II
Under the multiaxial scheme introduced with DSM-III of the American Psychiatric Association personality disorders or traits, as well as mental retardation, fall under this axis.

It is coded on Axis II, Arose. It is a developmental disorder which falls under mental retardation.

Actually, no. It is coded as an Axis I diagnosis under "Pervasive Developmental Disorders".
 

HA

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Thank you for correcting that, Dr Baxter.

I just assumed that all people who would be classified as having MR would be under AXIS II. Most people with Autism have MR but those on the Pervasive Development spectrum have less risk for MR such as Asperger's.

Would those with Autism who also have MR be coded under AXIS 1 and AXIS II ?
 

Peanut

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Oh Ok, I was thinking of axis II as disorders that persisted throughout life and were present since childhood (like sometimes autism does). Now I?m also thinking about autism compared with personality disorders and how they both affect how a person can relate to others. I know they aren?t the same, but it just got me thinking about it. I can see why Heartart thought it was Axis II, it seems like there could be a case made for either one (or maybe I?m completely off base). However, with that being said, not all people with autism are MR and so that must be one reason it?s not lumped together.

It is my understanding if someone has mental retardation and autism they would be dx on both axes.
 

David Baxter

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Yes. Just as someone could have an Axis I diagnosis of schizophrenia or Major Depressive Espisode and an Axis II diagnoses of, say, avoidant personality disorder or something.
 

HA

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Had a number of people at work confused on that one. Learn something new everyday. But here is how I think the DSM V, AXIS II should be changed.....
 

Peanut

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I know it is confusing. I think the DSM would be more user friendly if it directly said which axis to code the disorder on in the discription/criteria of the disorder (just my two cents).

Check this out, I was just emailed this, it kind of relates to the above article:
http://www.autismspeaks.org/science/research/autism_protein.php

Researchers Reveal Structure of Protein Altered in Autism

June 12, 2007 (San Diego, CA) - As a result of mapping the structure of the protein complex implicated in autism spectrum disorders, a research team led by scientists at the University of California, San Diego (UCSD) Skaggs School of Pharmacy and Pharmaceutical Sciences has discovered how particular genetic mutations affect this complex and contribute to the developmental abnormalities found in children with autism. Their work, published as the cover article in the June issue of the journal Structure, should help scientists pinpoint the consequences of other genetic abnormalities associated with the disorder.

“By understanding the three-dimensional structure of the normal protein, researchers can now make predictions about how mutations in the gene affect the structure of the gene product,” said first author Davide Comoletti, Ph.D., UCSD research associate at the Skaggs School of Pharmacy.

Autism spectrum disorders are developmental disabilities that cause impairments in social interaction and communication. Both children and adults with autism typically show difficulties in verbal and non-verbal communication, interpersonal relationships, and leisure or play activities.

Comoletti and colleagues studied the neuroligin family of proteins that are encoded by genes known to be mutated in certain patients with autism. The neuroligins, and their partner proteins, the neurexins, are involved in the junctions, or synapses, through which cells of the nervous system signal to one another and to non-neuronal tissues such as muscle. These structural studies on neuroligins and neurexins represent a major step toward defining the synaptic organization at the molecular level.

“Normally, individual neuroligins are encoded to interact with specific neurexin partners. The two partners are members of distinct families of proteins involved in synaptic adhesions, imparting ‘stickiness' that enables them to associate so that synapses form and have the capacity for neurotransmission,” said Palmer Taylor, Ph.D., Dean of the Skaggs School, Sandra & Monroe Trout Professor of Pharmacology, and co-principal investigator of the study, along with Jill Trewhella, Ph.D., of the University of Sydney, Australia and University of Utah.

Incorrect partnering that results when a mutant neuroligin fails to properly align at synapses helps explain why some autism spectrum disorders are manifested in subtle behavioral abnormalities that are seen at an early age.

“Abnormal synaptic development in nerve connections is likely to lead to cognitive deficits seen in patients with autism,” said Taylor. He added that synapse formation and maintenance occurs early in development when the infant brain is still plastic and formative. Therefore, by understanding the structural mutations that affect neurotransmission during development, new leads into drug therapies may emerge.

“We really don't know what causes autism, but this research represents a solid starting point,” said Sarah Dunsmore, Ph.D., program director with the National Institute of General Medical Sciences, part of the National Institutes of Health, which partly supported the study. “The work suggests that genetic mutations that alter the shape or folding of adhesion proteins in the nervous system influence their interactions. This is another example of how research on basic biological questions, such as the three-dimensional structures of proteins in the brain, can yield valuable medical insights.”

Taylor and colleagues have been studying the structure and function of acetylcholinesterase – a structurally related protein that mediates neurotransmission between nerves and between nerve and muscle – for the past 30 years. They began studying the neuroligins because of the similarity in structure and amino acid sequence with acetylcholinesterase.

The study was a multi-national collaboration, employing a synchrotron and a neutron source at two national laboratories to collect the X-ray and neutron scattering data necessary for resolving the structure. Additional contributors to this study include Alexander Grishaev, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD; Andrew E. Whitten, Bragg Institute, Australian Nuclear Science and Technology Organization; and Igor Tsigelny, UCSD Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences.

This work was supported in part by grants from the National Institutes of Health, the U.S. Department of Energy, and the Cure Autism Now Foundation.
 
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David Baxter

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I know it is confusing. I think the DSM would be more user friendly if it directly said which axis to code the disorder on in the discription/criteria of the disorder (just my two cents).

Actually, the DSM is pretty clear on what gets coded on Axis I versus Axis II. It takes time to understand the logic and structure of the DSM but it's not confusing once you're familiar with it.

That's perhaps part of the reason why diagnosis is a restricted act.
 

Peanut

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Probably. I was talking to my friend who is in her fourth year in a PsyD program in town here about which axis autism is coded on (prior to your interjection) and she said that people do it both ways (tisk tisk), some people code it on axis II because of the reasons HeartArt gave. Clearly it should only be done the correct way, but it sounds like there may be some confusion about it even among professionals.
 

David Baxter

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I'm not an expert in autism but I would not say that in general DSM is difficult to use for those who have been properly trained.

Of course, differential diagnosis requires, above all, a thorough grounding in psychopathology as well as in DSM itself.
 

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