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Autism Study Criticized

Controversial new research links autism to the environment, not genetics.

By | July 7, 2011

Identical twinsMICHAEL BLACKBURN

Contrary to decades of prior research, a new study of 192 sets of twins concluded that environmental factors, not genetics, accounts for the majority of the risk associated with autism spectrum disorders. Autism experts roundly criticized the findings, according to the Los Angeles Times.

The data in the study, published online July 4 in the Archives of General Psychiatry, was in line with previous studies: autism concordance rates of 77 percent for identical twins and 31 percent for fraternal twins. Yet when plugged into a statistical computer model to determine contributing roles of genes and the environment, the team concluded that only 38 percent of the risk for autism came from genetics while roughly 58 percent came from the environment shared by the twins.

"Their data are so similar to everybody else's, and yet they come up with another conclusion," Robert Plomin, a behavioral geneticist at King's College London, told the Times. "I don't know how this happened."

The study authors admitted their calculations were subject to a wide margin of error, and could be incorrect, the Times reported. Still, they argued that the findings highlight the need for more research into contributing environmental factors in autism.

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Avatar of: crl

Anonymous

July 7, 2011

Not very helpful, apart from showing how much justifiable controversy there is.  Regrettable, perhaps, at this level of scientific reporting is a lack of any attempt to distinguish between life events that cause apparantly irreversible epigenetic changes (see the recent literature) and those that might induce potentially more readily reversible "undesirable" thought processes.

Avatar of: Markriggle

Anonymous

July 7, 2011

The comment in the article: “Their data are so similar to everybody else’s, and yet they come up
with another conclusion,â€쳌 Robert Plomin, a behavioral geneticist at
King’s College London, told the Times. “I don’t know how this happened.â€쳌

Their data is seems not similar!  As Hallmayer in the original article states (for ASD): "Again, these dizygotic concordance rates are higher than previously reported and have a significant impact on the heritability analysis."  In dizygotic pairs  for autism, they found a 0.21(M) to 0.27(F) concordance rate, and for ASD, a 0.31-0.36 rate.  Plus they found monozygotic rates for autism and ASD to be lower than in other studies.  So dizygotic higher and monozygotic lower would mean more environmental impact.

Avatar of: Justinp

Anonymous

July 7, 2011

Environmental factors need to be heavily investigated for this disease - this is one for the epidemiologists - heavy metals, industrial chemicals, plastic byproducts, rocket fuel, etc etc etc, I think the answer will lie there somewhere.

Avatar of:

Posts: 0

July 7, 2011

Not very helpful, apart from showing how much justifiable controversy there is.  Regrettable, perhaps, at this level of scientific reporting is a lack of any attempt to distinguish between life events that cause apparantly irreversible epigenetic changes (see the recent literature) and those that might induce potentially more readily reversible "undesirable" thought processes.

Avatar of:

Posts: 0

July 7, 2011

The comment in the article: “Their data are so similar to everybody else’s, and yet they come up
with another conclusion,â€쳌 Robert Plomin, a behavioral geneticist at
King’s College London, told the Times. “I don’t know how this happened.â€쳌

Their data is seems not similar!  As Hallmayer in the original article states (for ASD): "Again, these dizygotic concordance rates are higher than previously reported and have a significant impact on the heritability analysis."  In dizygotic pairs  for autism, they found a 0.21(M) to 0.27(F) concordance rate, and for ASD, a 0.31-0.36 rate.  Plus they found monozygotic rates for autism and ASD to be lower than in other studies.  So dizygotic higher and monozygotic lower would mean more environmental impact.

Avatar of:

Posts: 0

July 7, 2011

Environmental factors need to be heavily investigated for this disease - this is one for the epidemiologists - heavy metals, industrial chemicals, plastic byproducts, rocket fuel, etc etc etc, I think the answer will lie there somewhere.

Avatar of:

Posts: 0

July 7, 2011

Not very helpful, apart from showing how much justifiable controversy there is.  Regrettable, perhaps, at this level of scientific reporting is a lack of any attempt to distinguish between life events that cause apparantly irreversible epigenetic changes (see the recent literature) and those that might induce potentially more readily reversible "undesirable" thought processes.

Avatar of:

Posts: 0

July 7, 2011

The comment in the article: “Their data are so similar to everybody else’s, and yet they come up
with another conclusion,â€쳌 Robert Plomin, a behavioral geneticist at
King’s College London, told the Times. “I don’t know how this happened.â€쳌

Their data is seems not similar!  As Hallmayer in the original article states (for ASD): "Again, these dizygotic concordance rates are higher than previously reported and have a significant impact on the heritability analysis."  In dizygotic pairs  for autism, they found a 0.21(M) to 0.27(F) concordance rate, and for ASD, a 0.31-0.36 rate.  Plus they found monozygotic rates for autism and ASD to be lower than in other studies.  So dizygotic higher and monozygotic lower would mean more environmental impact.

Avatar of:

Posts: 0

July 7, 2011

Environmental factors need to be heavily investigated for this disease - this is one for the epidemiologists - heavy metals, industrial chemicals, plastic byproducts, rocket fuel, etc etc etc, I think the answer will lie there somewhere.

Avatar of:

Posts: 0

July 8, 2011

What this paper suggests is that the environmental variables have become more variable between families. Autism and autistic spectrum disorders have become more common in recent decades, along with ADHD. This could be increased diagnosis, but correlates with greatly increased acceptability of female consumption of alcohol, a know neurotoxin. Behavioural symptoms of foetal alcohol syndrome resemble ASD. When checking rocket fuel and plastics, it might be worth epidemiologists investigating mothers' alcohol consumption. The problem would be that publishing a positive finding would spread some guilt about.

Avatar of:

Posts: 0

July 8, 2011

The large increase in diagnosis of ASD over recent years has not been confined to high functioning cases, a large percentage of children with ASD have a very clear level of disability which could not possibly have gone unnoticed 25 years ago when few of us had heard of autism - it is hard to classify autism to nail down exact figures, but 1986 was hardly the dark ages, yet no study has ever found even remotely similar numbers of severely handicapped children from that era.  This study is simply telling us what has been obvious for a long time, which is that something in the modern world is causing serious harm to a generation of children.  Sadly most of the available funding has been put into genetic research, hopefully this study will help lead to that changing and a serious effort being made to prevent as many as possible of the 40000 American children being diagnosed every year.

Avatar of:

Posts: 0

July 8, 2011

What this paper suggests is that the environmental variables have become more variable between families. Autism and autistic spectrum disorders have become more common in recent decades, along with ADHD. This could be increased diagnosis, but correlates with greatly increased acceptability of female consumption of alcohol, a know neurotoxin. Behavioural symptoms of foetal alcohol syndrome resemble ASD. When checking rocket fuel and plastics, it might be worth epidemiologists investigating mothers' alcohol consumption. The problem would be that publishing a positive finding would spread some guilt about.

Avatar of:

Posts: 0

July 8, 2011

The large increase in diagnosis of ASD over recent years has not been confined to high functioning cases, a large percentage of children with ASD have a very clear level of disability which could not possibly have gone unnoticed 25 years ago when few of us had heard of autism - it is hard to classify autism to nail down exact figures, but 1986 was hardly the dark ages, yet no study has ever found even remotely similar numbers of severely handicapped children from that era.  This study is simply telling us what has been obvious for a long time, which is that something in the modern world is causing serious harm to a generation of children.  Sadly most of the available funding has been put into genetic research, hopefully this study will help lead to that changing and a serious effort being made to prevent as many as possible of the 40000 American children being diagnosed every year.

Avatar of: H Fletcher

Anonymous

July 8, 2011

What this paper suggests is that the environmental variables have become more variable between families. Autism and autistic spectrum disorders have become more common in recent decades, along with ADHD. This could be increased diagnosis, but correlates with greatly increased acceptability of female consumption of alcohol, a know neurotoxin. Behavioural symptoms of foetal alcohol syndrome resemble ASD. When checking rocket fuel and plastics, it might be worth epidemiologists investigating mothers' alcohol consumption. The problem would be that publishing a positive finding would spread some guilt about.

Avatar of: James Lachman

Anonymous

July 8, 2011

The large increase in diagnosis of ASD over recent years has not been confined to high functioning cases, a large percentage of children with ASD have a very clear level of disability which could not possibly have gone unnoticed 25 years ago when few of us had heard of autism - it is hard to classify autism to nail down exact figures, but 1986 was hardly the dark ages, yet no study has ever found even remotely similar numbers of severely handicapped children from that era.  This study is simply telling us what has been obvious for a long time, which is that something in the modern world is causing serious harm to a generation of children.  Sadly most of the available funding has been put into genetic research, hopefully this study will help lead to that changing and a serious effort being made to prevent as many as possible of the 40000 American children being diagnosed every year.

Avatar of: Kay

Kay

Posts: 1457

July 9, 2011

The title and headlines associated with this study make the general public think of environmental toxins floating about in the environment, but that's not exactly what the study tested. I interpreted the findings as indicating that something happens in the mother's uterus between conception and birth which may be precipitated by something in the internal environment, eg. viruses, nutrients or foreign substances circulating in the blood at critical times during brain development. Of course these influences may have originated in the general environment, but they haven't affected all pregnant women the same way, or most children would be "autistic" to some degree. Also, the broadening of the term "autism" recently has included a lot more children whom I would have described as "odd" or FLK ("funny looking kid") 40 years ago when I first started associating with kids diagnosed autistic. Back then a lot of children with extremely low levels of cognitive function and severe epilepsy were often included as "autistic". With these kids their apparently "unreachable" nature made little difference to whether they could learn anything or conform to social norms- they neither responded to general instruction nor to specially adapted methods which worked for higher functioning individuals with autistic traits. These children also had probably experienced toxic influences in utero, but no one bothered to investigate whether it was genetic unless there were well-off and persistent parents. Surely if there was one clear genetic or environmental precipitant of autism, it would have been found by now. [??] My money is on neural development, organisation or migration during brief windows of prenatal development. It would be very difficult to examine the influence of biochemical factors in utero at precise times during brain formation to determine whether they stemmed from environmental or genetic triggers.

Avatar of:

Posts: 0

July 9, 2011

The title and headlines associated with this study make the general public think of environmental toxins floating about in the environment, but that's not exactly what the study tested. I interpreted the findings as indicating that something happens in the mother's uterus between conception and birth which may be precipitated by something in the internal environment, eg. viruses, nutrients or foreign substances circulating in the blood at critical times during brain development. Of course these influences may have originated in the general environment, but they haven't affected all pregnant women the same way, or most children would be "autistic" to some degree. Also, the broadening of the term "autism" recently has included a lot more children whom I would have described as "odd" or FLK ("funny looking kid") 40 years ago when I first started associating with kids diagnosed autistic. Back then a lot of children with extremely low levels of cognitive function and severe epilepsy were often included as "autistic". With these kids their apparently "unreachable" nature made little difference to whether they could learn anything or conform to social norms- they neither responded to general instruction nor to specially adapted methods which worked for higher functioning individuals with autistic traits. These children also had probably experienced toxic influences in utero, but no one bothered to investigate whether it was genetic unless there were well-off and persistent parents. Surely if there was one clear genetic or environmental precipitant of autism, it would have been found by now. [??] My money is on neural development, organisation or migration during brief windows of prenatal development. It would be very difficult to examine the influence of biochemical factors in utero at precise times during brain formation to determine whether they stemmed from environmental or genetic triggers.

Avatar of:

Posts: 0

July 9, 2011

The title and headlines associated with this study make the general public think of environmental toxins floating about in the environment, but that's not exactly what the study tested. I interpreted the findings as indicating that something happens in the mother's uterus between conception and birth which may be precipitated by something in the internal environment, eg. viruses, nutrients or foreign substances circulating in the blood at critical times during brain development. Of course these influences may have originated in the general environment, but they haven't affected all pregnant women the same way, or most children would be "autistic" to some degree. Also, the broadening of the term "autism" recently has included a lot more children whom I would have described as "odd" or FLK ("funny looking kid") 40 years ago when I first started associating with kids diagnosed autistic. Back then a lot of children with extremely low levels of cognitive function and severe epilepsy were often included as "autistic". With these kids their apparently "unreachable" nature made little difference to whether they could learn anything or conform to social norms- they neither responded to general instruction nor to specially adapted methods which worked for higher functioning individuals with autistic traits. These children also had probably experienced toxic influences in utero, but no one bothered to investigate whether it was genetic unless there were well-off and persistent parents. Surely if there was one clear genetic or environmental precipitant of autism, it would have been found by now. [??] My money is on neural development, organisation or migration during brief windows of prenatal development. It would be very difficult to examine the influence of biochemical factors in utero at precise times during brain formation to determine whether they stemmed from environmental or genetic triggers.

Avatar of:

Posts: 0

July 14, 2011

I am not a human geneticist (background in biochemistry, microbiology, molecular genetics) so am not specially qualified to analyze these data, but I have never seen concordance rates for non-twin siblings as high as stated for dizygotic twins (31%). I also find the monozygotic twin rates of concordance (77%) to be surprisingly low, given the essentially identical genomes. Since twins of both kinds have the uterine environment in common it seems clear that some aspect of that (uterine) environment has a substantial influence on the development of autism. 

Avatar of:

Posts: 0

July 14, 2011

I am not a human geneticist (background in biochemistry, microbiology, molecular genetics) so am not specially qualified to analyze these data, but I have never seen concordance rates for non-twin siblings as high as stated for dizygotic twins (31%). I also find the monozygotic twin rates of concordance (77%) to be surprisingly low, given the essentially identical genomes. Since twins of both kinds have the uterine environment in common it seems clear that some aspect of that (uterine) environment has a substantial influence on the development of autism. 

Avatar of: Kenneth Roy

Anonymous

July 14, 2011

I am not a human geneticist (background in biochemistry, microbiology, molecular genetics) so am not specially qualified to analyze these data, but I have never seen concordance rates for non-twin siblings as high as stated for dizygotic twins (31%). I also find the monozygotic twin rates of concordance (77%) to be surprisingly low, given the essentially identical genomes. Since twins of both kinds have the uterine environment in common it seems clear that some aspect of that (uterine) environment has a substantial influence on the development of autism. 

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