First biomarker evidence of DDT-autism link

Via dailykos.com and sciencedaily.com


First biomarker evidence of DDT-autism link

National birth cohort study finds DDT metabolites in the blood of pregnant women are associated with elevated odds of autism in offspring

Date:

August 16, 2018

Source:

Columbia University's Mailman School of Public Health

Summary:

A study of more than 1 million pregnancies in Finland reports that elevated levels of a metabolite of the banned insecticide DDT in the blood of pregnant women are linked to increased risk for autism in the offspring. The study is the first to connect an insecticide with risk for autism using maternal biomarkers of exposure.

Via nature.com

Brown's team found no correlation between the PCB by-product and autism. But when they measured DDT by-product levels in the blood samples, they found that mothers with high concentrations of this chemical — those in the top quartile — were 32% more likely than women with lower DDT levels to give birth to children who developed autism. The likelihood that a child with autism accompanied by intellectual disability was twice as high in mothers with elevated DDT levels compared to those with lower levels.
...
Brown cautions that although there seems to be a link between autism and DDT exposure, the overall risk of having a child with the disorder is low — even among women with high DDT levels. His group plans to look at other organic chemicals in the Finnish database to determine whether they might affect fetuses by interacting with DDT. 

Jonathan Chevrier, an epidemiologist at McGill University in Montreal, Canada, is interested in knowing whether DDT levels are linked to intellectual disability in children who do not have autism. He is currently following more than 700 children in South Africa — where DDT is still used — which could provide hints as to the mechanism by which the pesticide might affect the brain. It’s an important question, he says, given how much DDT persists in the environment, even in places that have banned its use. “At this point, essentially the entire planet is contaminated with DDT,” he says.

More indications that g is a myth

One indication that Spearman's g (upon which IQ is based) is an artifact of positive correlations among various intelligence test measures than a real thing is that there are subpopulations among which these measures do not correlate in the same way as among the general public.

An example is here: (note, my interpretation of their findings):

Psychol Sci. Author manuscript; available in PMC 2015 Jan 8.

Published in final edited form as:

Psychol Sci. 2007 Aug; 18(8): 657–662.

doi:  10.1111/j.1467-9280.2007.01954.x

PMCID: PMC4287210

NIHMSID: NIHMS653064

The Level and Nature of Autistic Intelligence

Michelle Dawson,¹ Isabelle Soulières,^1,2 Morton Ann Gernsbacher,³ and Laurent Mottron^1,2

To quote:

For example, no autistic child scored in the “high intelligence” range on the WISC-III, whereas a third of the autistic children scored at or above the 90th percentile on the Raven’s Matrices. Only a minority of the autistic children scored in the “average intelligence” range or higher on the WISC-III, whereas the majority scored at or above the 50th percentile on the Raven’s Matrices. Whereas a third of the autistic children would be called “low functioning” (i.e., in the range of mental retardation) according to the WISC-III, only 5% would be so judged according to the Raven’s Matrices.

In striking contrast to the autistic children, the nonautistic control children did not show a significant difference between their Raven’s Matrices scores and their WISC-III Full Scale, Verbal Scale, or Performance Scale scores .

So, if there was a real thing X corresponding to Spearman's g that represented the intelligence of a human brain, then the general positive correlation in the general population between WISC and Raven's Matrices is not measuring this thing X.  But it is these kinds of positive correlations among the various tests' results that is supposed to be measuring this real thing that is approximated by Spearman's g.

Autism breakthrough?

Studies: Autism risk linked to herpes infection during early pregnancy

NEW YORK - Scientists from Colombia University and the Norwegian Institute of Public Heath have discovered that women actively infected with genital herpes during early pregnancy was twice as likely to have a child diagnosed with autism spectrum disorder (ASD) later on in life.

 Alarmingly:

About one in five American women has HSV-2, also known as genital herpes. HSV-2 is a highly contagious and lifelong infection, usually spread through sex.

More here:

The finding mirrors earlier epidemiological data indicating that activation of the maternal immune system during early-to-mid-pregnancy is associated with long-term developmental and behavioral problems in offspring.

However, of these pathogens examined : Toxoplasma gondii, rubella virus, cytomegalovirus, and herpes simplex viruses type 1 and 2, only herpes simplex virus type 2 was implicated.

“The cause or causes of most cases of autism are unknown,” says senior author W. Ian Lipkin, director of the Center for Infection and Immunity and the John Snow Professor of Epidemiology at Columbia’s Mailman School. “But evidence suggests a role for both genetic and environmental factors. Our work suggests that inflammation and immune activation may contribute to risk. Herpes simplex virus 2 could be one of any number of infectious agents involved.”