If vaccines don’t cause autism, what does? The scientific community owes the world an answer to this question.
Amidst measles outbreaks like the ones unfolding in New York and Washington state, doctors have a responsibility to the public beyond haranguing parents to vaccinate their children. We must explain how we know that vaccines do not cause autism, and instead explain why autism develops.
When the theory that vaccines might cause autism was advanced by the now-discredited British physician Andrew Wakefield in 1998, based on a case series of 12 patients, the scientific community took the claim seriously.
The landmark test of the hypothesis was published in 2002 by the New England Journal of Medicine, the world’s premier medical journal. Researchers examined the records of all 537,303 children born in Denmark from 1991-8, because vaccination there was optional.
Although 18% of children were unvaccinated during that time, their risk of autism was 8% higher (although not statistically significantly) than comparable vaccinated children. The researchers used standard statistical methods to compare the effect of vaccination on autism risk given the child’s age, sex, year of birth, socioeconomic status, mother’s education, birth weight, and gestational age.
Put simply, if vaccines caused autism, the risk of autism in unvaccinated children should have been much lower or even zero.
Instead, it was basically the same as in vaccinated children. Several other studies since then have also found no link between vaccines and autism. Meanwhile, evidence later emerged that Wakefield stood to profit handsomely from lawsuits against vaccine manufacturers, and that he had cherry-picked his data. Ten of his co-authors retracted their support, and England took away his license.
So, what does cause autism?
Autism is a severe disease with deep impacts on affected families, and they deserve answers. Also, the neuroscience of debunking myths shows that people will adhere to a false belief, even after proof, unless they can replace it with a better one.
Science has been hard at work answering this question, especially since the rate of autism has risen in recent decades.
Autism, like cancer, is a complex disease of many causes and manifestations. It is a spectrum of diseases, with a corresponding array of causes. Both cancer and autism strike via the “two-hit” hypothesis—genetic predisposition and an environmental trigger.
Several genetic markers of autism risk have already been identified. Meanwhile, recent large studies suggest that poor maternal health during pregnancy and around childbirth—when the child’s brain is developing—can unsurprisingly serve as the environmental trigger.
Several factors have consistently been associated with increased risk of autism in large studies. These are: maternal obesity, maternal diabetes, older fathers, older mothers, low birth weight infants, viral infections in the first or second trimester, and the use of certain prescription drugs while pregnant. All these environmental factors have increased substantially in the past decades, which could explain the rise in autism.
Many physicians believe that such conditions cause inflammation in the uterus, altering brain development in genetically susceptible children. Signs of autism often appear in children in the first year of life before they receive a single MMR vaccination, further implicating pregnancy as the vulnerable period for developing autism.
Meanwhile, vaccines represent one of mankind’s greatest achievements. Vaccination eradicated our world of smallpox, once the decimator of societies. We have nearly eliminated polio, which used to paralyze thousands of children per year.
Vaccination could eliminate the very contagious and miserable measles, which causes blindness, brain inflammation, or death in one child per thousand cases. Measles also weakens a child’s immune system against other diseases, placing unvaccinated children at further increased risk of death.
Vaccines for deadly diseases such as HIV, malaria and even some cancers represent a holy grail of medical research. For example, the HPV and HBV vaccines have dramatically reduced the rate of cervical and liver cancer, respectively.
Vaccines are one of the few medical interventions that actually save our health care system money, with each dollar spent on vaccines saving $10 in societal costs. They also prevent suffering and death.
Concerned parents are right to ask questions. We have the answers. If you want healthy children, vaccinate them, and help their mothers be healthy during pregnancy.