The anti-vaxxers are hoist with their own petard—again! According to a long article in Newsweek by Jessica Firger, the organization SafeMinds, dedicated to ending the “autism epidemic” has funded medical research designed to show that autism was a result of vaccination: presumably via the antigens in vaccines themselves and certainly by the preservatives in vaccines, notably the mercury compound thiomersal, long suspected, but never shown, to cause autism. (Note that for nearly all childhood vaccines, this compound is either no longer present or added in negligible amounts.)

All scientists know that it’s not good practice to do an experiment or make an observation if one result is immensely more desirable (and career-making) to you than another. That is a temptation to fudge results or, more often, to practice “confirmation bias”: ignoring those results inimical to your desired hypothesis. But wanting a result doesn’t make it more likely. As Voltaire said in 1763: “The interest I have in believing in something is not proof that that something exists.”

But SafeMinds fell into this trap, funding work designed to show a given outcome. Now I can understand their desire to find the cause of the autism “epidemic”, although we still don’t know if it’s really an epidemic or a change in diagnoses. Parents, who would feel guilty if they contributed environmentally or genetically to their kids’ autism, want to find some external cause, and of course many of them are desperate to find a cure for their disturbed children. But nature is nature, and what happened in the present case is predictable from previous results: the SafeMinds-funded research found that vaccinations (either with or without thiomersal) didn’t show any connection to autism, at least to indicators of the syndrome in primates.

One of the papers from this work, just published in the Proceedings of the National Academy of Sciences (reference and link below) gave totally negative results. The abstract is very clear:

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder. Some anecdotal reports suggest that ASD is related to exposure to ethyl mercury, in the form of the vaccine preservative, thimerosal, and/or receiving the measles, mumps, rubella (MMR) vaccine. Using infant rhesus macaques receiving thimerosalcontaining vaccines (TCVs) following the recommended pediatric vaccine schedules from the 1990s and 2008, we examined behavior, and neuropathology in three brain regions found to exhibit neuropathology in postmortem ASD brains. No neuronal cellular or protein changes in the cerebellum, hippocampus, or amygdala were observed in animals following the 1990s or 2008 vaccine schedules. Analysis of social behavior in juvenile animals indicated that there were no significant differences in negative behaviors between animals in the control and experimental groups. These data indicate that administration of TCVs and/or the MMR vaccine to rhesus macaques does not result in neuropathological abnormalities, or aberrant behaviors, like those observed in ASD.

Now of course this was done in macaques, and one could argue that they don’t get autism (I have no idea), but macaques are biologically close to humans, and autism in humans shows not just a spectrum of behavior disorders, but is also associated with brain changes: changes in the size of neurons and reduced numbers of “Purkinje cells” in the brain, as well as other brain abnormalities and screwups in biochemical pathways. No abnormalities were seen regardless of whether the vaccinations contained tiomersal or not.

Another SafeMinds-funded paper, published this June in Environmental Health Perspectives (free download at link; reference below) showed that the same group of infant macaques used in the PNAS paper displayed no behavioral or developmental anomalies compared to controls.

Now one would think that by ruling out vaccines as a cause of autism—something that’s already been done by tons of research—SafeMinds would be happy. Now we can inoculate our children without fear of turning them autistic, and thus protect them against infectious disease. And we have ruled out one cause of the autism “epidemic”—if it is an epidemic. But confirmation bias among autism advocates dictates otherwise. As Newsweek reports:

SafeMinds, the nonprofit that funded the research, is not happy with the results. Representatives from the group say the findings contradict both an earlier pilot study and interim progress reports the organization received from the researchers.

And they cite two “pilot studies” that claim to show otherwise:

The pilot study, undertaken at the University of Pittsburgh, led to two papers, both published in 2010, showing that the vaccines did in fact affect brain development in infant macaques. One paper, published in Acta Neurobiologiae Experimentalis [pdf here], looked at the development of the amygdala region of the brains of monkeys that received the complete U.S. childhood vaccine schedule from the 1990s and then underwent MRI and PET scans at 4 and 6 months of age.

The researchers reported that amygdala volume was different in monkeys that received the vaccines versus those that did not. They also reported differences in certain opioid receptors in the brains of monkeys in the vaccine group.

Note, though, that this pilot study used only 16 macaques (as opposed to the 79 in the PNAS and EHS studies and so the sample size was very small.  Newsweek continues:

The other paper, from the Journal of Toxicology and Environmental Health, looked at differences in the reflexes of baby monkeys that received a single dose of thimerosal-containing hepatitis B vaccine versus those in a control group. In that paper, the researchers reported that “in exposed animals there was a significant delay in the acquisition of root, snout, and suck reflexes, compared with unexposed animals.”

If you check the paper, though, the sample size was six in the control group and seven in the experimental group, an even smaller  sample than in the ANE paper. The surgeon-blogger Orac has analyzed these “pilot studies” and found them “bad science”; you can see his first analyses here, here, Steve Novella’s critique here, and Orac’s overall conclusions (published Sept. 15) here. (Curiously, Laura Hewitson, an erstwhile collaborator with the discredited anti-vaxxer Andrew Wakefield, is an author of the PNAs study, and is quoted below defending it.) Much of the problem appears to have stemmed from one or two primates that affected the entire study.

Orac’s conclusion:

For instance, Laura Hewitson followed up her first study with another one in 2009 and yet another in 2010. All were bad science. All were preliminary studies at best. All claimed to relate the pediatric vaccine schedule to neurodevelopmental disorders. All were touted by antivaccinationists. One was withdrawn.

But Orac also faults the Gadad et al. study not for its methods, but for beating a dead horse: wasting the lives of primates testing a hypothesis that has already been amply refuted. He considers it no longer useful to study the connection between vaccinations and autism.

At any rate, which set of papers does SafeMinds accept? You guessed it;

SafeMinds also believes that the research team behind the new PNAS study may have cherry-picked their data. SafeMinds Director Lyn Redwood, a registered nurse, says she received an email in 2013 from the researchers reporting a “statistically significant” 11 percent reduction in certain types of hippocampal cells in the vaccine groups. But she says the authors did not include these findings in the new paper.

Dr. Laura Hewitson, director of research for the Johnson Center for Child Health & Development, an adjunct associate professor in the Department of Psychiatry at the University of Texas Southwestern Medical Center, a lead researcher on project and co-author on all four papers, says that at the time that email was sent, it was also made clear to SafeMinds “that the data should be treated as preliminary until all of the animals had completed the study.” She added that none of the study’s procedures changed once her team moved from the pilot program to a larger sample.

“The same assessments were performed on a much larger number of primates by a team of behaviorists with decades of experience working with nonhuman primate infants,” Hewitson tells Newsweek. “For example, in the pilot study we examined 13 different neonatal reflexes from birth to 14 days of age in just two groups of animals. In the current study, we examined those same 13 reflexes, plus six others from birth to 21 days of age, in six groups of animals—a much more comprehensive experimental design.”

. . . “As you can see, we have done everything possible to ensure the integrity of the data. My co-authors and I stand by our published findings,” she says. “The comprehensive nature of the current study underscores why the findings from the pilot study should be interpreted with an abundance of caution, given the small number of animals included.”

But such is the faith that the anti-vaxxers have in their theory that they feel that the research they funded that didn’t show what they wanted must have been nefariously redacted. But why would the researchers do that?

Here’s more of SafeMind’s confirmation bias:

But Sallie Bernard, president of SafeMinds, says she would at least like to see a re-analysis of the newest data. “We feel that embedded within these data sets there are animals that have potentially an adverse reaction to this vaccine schedule that would mirror what happens in human infants,” she says. “The majority who get vaccines are fine, but we believe there is a subset that have an adverse reaction to their vaccines. By looking at the raw data, not data in aggregate, we may be able to identify the subgroup that had that reaction.”

Well, I’m sure they’ll be able to get the raw data: the law mandates that that be made public. I look forward to their reanalysis.

After looking at all these papers, Orac’s and Novella’s critiques, and reviewing the other research they cite, it’s pretty clear that Orac is right: we no longer need to spend money testing whether vaccines, with or without thiomersal, cause autism. One might as well keep testing the idea that bad air (“mal aria” in Italian) causes malaria.

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Gadad, B. S. et al. 2015. Administration of thimerosal-vaccines to infant rhesus macaques does not result in autism-like behavior or neuropathology. 112:12498-12503. Proc. Nat. Acad. Sci. USA

Curtis, B. eta l. 2015. Examination of the safety of pediatric vaccine schedules in a non-human primate model: assessments of neurodevelopment, learning, and social behavior.  Envtl. Health Perspectives 123:579-589.