Which generation likely has the most autistic people?

[Au Naturel]

Some really good responses and info above.

Just to add my opinion, I think pesticides are one of the main prime suspects for the initial creation of the genetic variations that result in autism. Once you have them you can pass them down but that does not explain any increase as far as percent of population - if you accept early studies determining that those on the spectrum have fewer children statistically then NTs.


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In this theory, increase in autism cases would roughly follow pesticide use. I should add that the typical scenerio expressed in this theory is that it is your mother's exposure to pesticide that causes the changes/variations.

As pesticide use differs significantly from one country to the next you might expect to see this reflected in the statistics but this is hampered greatly by the difference in diagnosis criteria (or even diagnosing at all) in countries. This is an interesting list of counties listing their pesticide use, not by tonnage but by the density of use (ie how many kilos of pesticide per hectare, etc).

Pesticide use by country

Pesticides have nothing to do with it. We are vastly more careful in the US about pesticide use than we once were. Silent Spring and the environmental movement achieved an awful lot. We live in a much cleaner environment than when I was young.

The US is one of the lower users of pesticides. By those numbers, China should be buried in autistic children. they use 5-6 times as much per acre as the US.

 

[Crossbreed]

It would affect nonautistic children as much as autistic ones. It would show up in vast numbers.

Not if immune system issues were part of the equation.

Part of this is because more borderline cases have gotten diagnosed.

My two children and their classmates were clearly not borderline.

My daughter lacked not only speech, but language development. She could follow classroom instructions just as well as any other 18 month old. She would randomly bite people and either poop in her pants or on the floor.*

My son would not let trivial matters (like the teacher's lesson) distract him from whatever was on his mind and he would get louder until he was acknowledged.

My ASD1 kids were not placed in special ed. They remained in their regular classrooms with 504 plan adjustments to their workload. One was even in two-year advanced math classes.

*Special ed. helped her to get potty-trained, but she will still do the above if a toilet is not readily available, and she does not know how to wipe in back.

 

[MorganVioletHart]

I feel like its actually equal across generations, but autism wasn't even recognized as a disability until the 1990s. People were not aware of identifying autism for what it is and neurodiversity wasn't part of the conversation before the millenial generation. Now its a lot more common for people to cone at autistic and be proud of how they function atypically.

I also found out that because I'm transgender it's actually a lot more likely for me for be autistic. Research shows gender diverse people are far more likely to be neurodiverse than cisgender people. So I feel like there are other movements that relate to advocating for understanding and awareness of what neurodiverse people experience, particularly with the gay, poc, and other disability communities and their fights for their own rights in a world that oppresses anyone different than the white, cisgender, typical ways of functioning.

 

[Crossbreed]

Part of this is because more borderline cases have gotten diagnosed. But also, most schools in the past would toss a kid with severe intellectual disabilities in the special ed bucket without any further diagnosis.

Here is a quote from the first page of a 2020 California report PDF,*
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More than 2 decades ago, autism cases began to increase
More than two decades ago, California began to recognize a surprising increase in autism cases in its Department of Developmental Services (DDS) system. In 1999, DDS issued a report that showed a startlingly rapid rise over the previous decade in the number of persons receiving services for autism. The DDS is the California agency that is responsible for coordinating services for persons of all ages with qualifying developmental disabilities. In 1999 it reported that its caseload of the most severe form of autism had increased from 3,864 to 11,995, a 210% increase, far greater than the increases in other developmental conditions. The agency concluded, referring to its autism caseload:

“…the number of young children coming into the system each year is significantly greater than in the past, and that the demand for services to meet the needs of this special population will continue to grow.”
–California DDS 1999

In 2003, the DDS issued an update, which demonstrated that the rise in the caseload had not only continued unabated, but was becoming steeper every year.
In 2007, another DDS report documented the continuing dramatic increase in the autism caseload, noting that “the number of persons with autism being served by the regional centers rose 26 times faster than that of the general California population.”
In 2009, scientists at the UC Davis MIND Institute analyzed the California autism prevalence and incidence (i.e., new diagnoses) rates based on the DDS data and all births in the state. Comparing children born from 1990 to 2002, they confirmed a continuing increase in rates of autism diagnoses that was substantial —a 600% rise —and determined that this growth could not be explained by changes in the underlying population or changes in the way autism was diagnosed.
Now, nearly 20 years after that period, DDS data reflects a continuing upward surge in autism in the state. The purpose of this report is to help bring the public—including individuals and families affected by autism, service providers, and local, state, and federal policymakers—up to date about this urgent public health issue that seldom receives the attention it warrants...
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From page 10,...
California DDS and US CDC have similar trends
•CDC Autism and Development Disability Monitoring Network (ADDM) reports show higher estimated prevalence than the California DDS finds
•This is expected, as the California DDS has more stringent criteria and excludes milder cases
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*Report found at
https://sfautismsociety.org/californias-autism-crisis/

 

[Tom]

Pesticides have nothing to do with it. We are vastly more careful in the US about pesticide use than we once were. Silent Spring and the environmental movement achieved an awful lot. We live in a much cleaner environment than when I was young.

The US is one of the lower users of pesticides. By those numbers, China should be buried in autistic children. they use 5-6 times as much per acre as the US.

That is likely incorrect. There are some studies that indicate that exposure to pesticides increases, sometimes dramatically, the chance a child will have autism. I will provide links if you are interested.

 

[Tony Ramirez]

I was never exposed to pesticide, neither was my sister when we were being developed yet we still got autism.

 

[Crossbreed]

I was never exposed to pesticide, neither was my sister when we were being developed yet we still got autism.

These studies usually mean (the severe co-morbids of) ASD2+, not ASD1 (which is thought to be hereditary).

The comparative pesticide pollution between America & China is a relevant consideration, though.

 

[Progster]

I wonder if more autistic people are having children than they used to? As autism is likely to be passed on genetically, that would mean a higher proportion of autistic people in the general population.

 

[Crossbreed]

ASD1 is hereditary. The severe co-morbids of ASD2+ are not, or their numbers would be more regular.
They (ASD2+) were about 1:10,000 before 1979 and according to California, its rate is increasing, not just holding steady. And it is worldwide, not just Silicon Valley. Neurds did not suddenly start marrying neurds, in unison.

From California’s Autism Crisis – Autism Society San Francisco Bay Area ,
"These numbers imply substantial effect from increases in causal factors."

 

[Neonatal RRT]

The autistic brain, at the cellular, genetic, and morphological level, is different than a "neurotypical" brain. There is no doubt of this. It has been studied extensively. So the idea of some sort of postnatal event "triggering" autism in a child is almost non-existent. What appears to be consistent within the literature is the associations with genetics, as well as, intrauterine and perinatal "triggers", such as hormonal milieu, placental circulatory abnormalities, and age of the parents. The hormonal milieu can be affected by elevated insulin, hypothyroidism, elevated estrogens, chronic inflammation, infectious disease, toxins, maternal age, etc. If there is any "injury" that is to occur, there are some associations with extreme prematurity and intrauterine hypoxic injuries, things that would effect the development of the brain during early development. When I say this, I mean early development, before the neurons have migrated outward from the germinal matrix in the areas of the hypothalamus and central ventricular structures, which usually starts after 26 weeks gestation. So, we are talking before 26 weeks in order for an "injurious" event or condition to be associated with an increased risk of developing autism.

Given all the data, it would suggest that the age of the parents will present the greatest influence on whether or not they will have a child with autism. This is considering the fact that many parents are now having children in their 30's and 40's and not in their 20's. At this age, parents are more likely to have gained body fat affecting their hormones (insulin, testosterone, and estrogen), are more likely to be hypothyroid, more likely to have built up toxins in their body, more likely to have a preterm birth, more likely to have DNA strand breaks and "chronic" health conditions, etc. I know that some people don't want to accept this, but young, healthy, trim, fit parents are at a very low risk for having health issues with their infants.

 

[Crossbreed]

So the idea of some sort of postnatal event "triggering" autism in a child is almost non-existent.

I have never heard of any hypothesis where autism, itself [ASD1], was being so triggered, just the severe co-morbids associated with ASD2+. (And the California report supports this in its distinction between DDS autism vs. 504 autism.)

 

[Au Naturel]

That is likely incorrect. There are some studies that indicate that exposure to pesticides increases, sometimes dramatically, the chance a child will have autism. I will provide links if you are interested.

There aremany countries that have four

The autistic brain, at the cellular, genetic, and morphological level, is different than a "neurotypical" brain. There is no doubt of this. It has been studied extensively. So the idea of some sort of postnatal event "triggering" autism in a child is almost non-existent. What appears to be consistent within the literature is the associations with genetics, as well as, intrauterine and perinatal "triggers", such as hormonal milieu, placental circulatory abnormalities, and age of the parents. The hormonal milieu can be affected by elevated insulin, hypothyroidism, elevated estrogens, chronic inflammation, infectious disease, toxins, maternal age, etc. If there is any "injury" that is to occur, there are some associations with extreme prematurity and intrauterine hypoxic injuries, things that would effect the development of the brain during early development. When I say this, I mean early development, before the neurons have migrated outward from the germinal matrix in the areas of the hypothalamus and central ventricular structures, which usually starts after 26 weeks gestation. So, we are talking before 26 weeks in order for an "injurious" event or condition to be associated with an increased risk of developing autism.

Given all the data, it would suggest that the age of the parents will present the greatest influence on whether or not they will have a child with autism. This is considering the fact that many parents are now having children in their 30's and 40's and not in their 20's. At this age, parents are more likely to have gained body fat affecting their hormones (insulin, testosterone, and estrogen), are more likely to be hypothyroid, more likely to have built up toxins in their body, more likely to have a preterm birth, more likely to have DNA strand breaks and "chronic" health conditions, etc. I know that some people don't want to accept this, but young, healthy, trim, fit parents are at a very low risk for having health issues with their infants.

There is a connection to older fathers in particular. Not huge, but measurable. Some (not most) autism-related genes have been correlated to the Y chromosome. As you age, the DNA in your gametes also ages and gains defects. Male children are more susceptible to it because they only get one Y, and that's only from the father. Females get two Xs, so a defect in the father's X contribution can be counterbalanced by a lack of a defect at that location in the mother's contribution. Autism is not the only condition this applies to.

The Y chromosome turns off and modulates other genes throughout the genome more than it creates traits itself. Defects in the Y have been shown to allow other genes in nonY chromosomes to express traits that would normally NOT be expressed. That is considered more likely than a direct link to a specific Y chromosome gene as a cause.

I ran a full DNA test and found that I have two genes correlated with autism. (Finding a correlation is easy. Proving causality has only occurred for a couple of genes I'm aware of.) The test would not pick up on any accumulated genetic defects in gametes due to age. I suppose that will be the next stage of genetic testing.

China uses 5 times as much pesticide per acre as the US. Unlike the US, they have few regulations on how and when it is applied. (They also have poor environmental protections in every other area.) A billion people live there in 2nd and 3rd world conditions with little prenatal care. If environmental toxins were the cause, one would expect China (and other massively polluted countries like them) to have spectacular rates of autism compared to the US. I don't see any evidence for this.