Autism Symptoms and Causes of Autism: Autism and Vaccinations

A person with mild autistic symptoms is at one end of the spectrum. A person with more serious symptoms of autism is at the other end of the spectrum. But they both have a form of ASD.

These parents report that their children were "normal" until they received the MMR vaccine. Then, after getting the vaccine, their children started showing symptoms of autism. Because the symptoms of autism begin to occur around the same time as the child's MMR vaccination, parents and families see the vaccine as the cause of the autism. However, just because the events happen around the same time does not mean that one caused the other. Although children receive many other vaccines in addition to the MMR vaccine, these other vaccines have not been identified as possible causes of autism.

These parents' beliefs and observations were reinforced by a small study of bowel disease and autism, published by Wakefield and his colleagues in Wakefield et al The study's authors suggested that there was a link between the MMR vaccine and autism. This study did not include scientific testing to find out if there was a link. The authors relied on the reports of parents and families of the 12 children with autism involved in the study to make their suggestion.

The study did not provide scientific proof that there was any link. Since this study was published in , a number of other studies have also been published that suggested a link between the MMR vaccine and autism Singh et al ; Horvath et al ; O'Leary et al ; Wakefield et al ; Kawashima et al , but none of these provide scientific proof of such a link.

To date there is no definite, scientific proof that any vaccine or combination of vaccines can cause autism. It's important to know that vaccines actually help the immune system to defend the body. The immune system has cells, sometimes called memory cells, that remember diseases. If these cells meet a disease, they keep track of what it looks like so they can recognize it later. When the memory cells meet up with the disease again, they recognize it and know they need to get rid of it.

They call in the other parts of the immune system to get rid of the disease. In some cases, memory cells can recognize a disease without ever having to meet up with it, which is called "natural" immunity.

In other cases, the cells need some help to become familiar with a disease. That help comes in the form of a vaccine. The vaccine takes a form of the disease that doesn't make you sick and introduces it to the memory cells so they know what to look for later. If the memory cells ever bump into the disease again, they know to call in other cells in the immune system to protect the body and get rid of the disease. The memory cells of a child keep track of diseases well into adulthood, preventing such diseases by getting rid of them quickly.

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• Vaccines and Autism: A Tale of Shifting Hypotheses.

In this way, vaccines help the immune system by making it easier to remember diseases. This independent panel examined completed studies, on-going studies, published medical and scientific papers, and expert testimony to assess whether or not there was a link between autism and the MMR vaccine. Parents, scientists, and practitioners presented information on this topic to a multidisciplinary panel of experts.

Based on its review, the AAP also found that the available evidence did not support the theory that the MMR vaccine caused autism or related disorders. In , Taylor and colleagues published a study Taylor et al that argued against the suggested link between autism and the MMR vaccine suggested in the Wakefield study. Taylor's study looked at all the known cases of ASD in children living in certain districts of London who were born in , or later. Researchers then matched the ASD patients with an independent registry of vaccinations.

The results of this study showed that:. Also in , the United Kingdom's Committee on Safety of Medicine examined hundreds of reports collected by lawyers of patients with autism and similar disorders that families said they developed after receiving the MMR or MR vaccine. After a systematic, standardized review of the case information, the Committee found that the information did not support any link between vaccines and autism. A study, done in Sweden in , also showed no evidence of association between the MMR vaccine and autism.

The study compared the number of autism cases in children from two Swedish towns before , when local doctors first started using the MMR vaccine, and after Another study, done in England in , looked at any possible link between the measles-specific vaccine one part of the MMR vaccine and different problems that result from damage to the nervous system, such as learning disabilities and behavior problems.

These researchers found no proof that the measles vaccine was in any way linked to long-term damage to the nervous system Miller et al This Act, which was signed into law in October , charges the NIH with the, "Expansion, intensification, and coordination of activities of the NIH with respect to research on autism. In addition, the NIH will form a committee with representatives from parents' groups and other federal agencies to coordinate autism research activities throughout the federal government and to enhance efforts to educate doctors and other health care professionals, and parents, and other child caretakers, about autism.

The diseases that the MMR vaccine prevents, measles, mumps, and rubella also called German measles , are actually very serious. Many times, the symptoms and effects of these diseases are just as serious and life-long as the symptoms of autism. In some cases, these diseases result in death. If people stop getting vaccines, the number of cases of these diseases will increase, and with it, the number of deaths and serious health problems.

Measles is a life-threatening disease that spreads quickly and easily. Before the vaccine was available in the U. The symptoms of measles include a rash, high fever, cough, runny nose, and watery eyes. But, if not treated, these seemingly mild symptoms can lead to conditions such as pneumonia, seizures, and water and swelling around the brain. For one-in to one-in-1, people, measles causes death. High levels of immunization in the U.

But in poorer countries of the world, where vaccines aren't as common, nearly , people died from causes related to measles in Mumps, which the MMR vaccine also protects against, was a major cause of deafness in children before doctors started using vaccines to prevent it.

Even though it tends to be mild in children, mumps is dangerous for adults, with side effects that can include paralysis, seizures, and fluid in the brain. Before the vaccine for mumps was available, there were about , cases of mumps each year in the U. In , there were only cases of mumps in the U. The last disease prevented by the MMR vaccine, rubella, is harmful to pregnant women and their growing babies.

If a pregnant woman gets rubella, her baby may develop a life-long condition that includes heart defects, mental retardation, and deafness. In some cases, the baby's condition is so severe that the baby dies. In , before the vaccine for rubella was available, 20, babies were born to mothers who had rubella. Author manuscript; available in PMC Jul Gerber and Paul A. Author information Copyright and License information Disclaimer. The publisher's final edited version of this article is available at Clin Infect Dis.

See other articles in PMC that cite the published article. Abstract Although child vaccination rates remain high, some parental concern persists that vaccines might cause autism. MMR On 28 February , Andrew Wakefield, a British gastroenterologist, and colleagues [ 1 ] published a paper in The Lancet that described 8 children whose first symptoms of autism appeared within 1 month after receiving an MMR vaccine. Table 1 Studies that fail to support an association between measles-mumps-rubella vaccine and autism.

Source Study design Study location Taylor et al. Open in a separate window. Ecological studies Researchers in several countries performed ecological studies that addressed the question of whether MMR vaccine causes autism. In the United Kingdom, researchers evaluated autistic children born from through who were identified by computerized health records from 8 health districts [ 5 ]. Although a trend toward increasing autism diagnoses by year of birth was confirmed, no change in the rates of autism diagnoses after the introduction of MMR vaccine was observed. Further, MMR vaccination rates of autistic children were similar to those of the entire study population.

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Also, investigators did not observe a clustering of autism diagnoses relative to the time that children received MMR vaccine, nor did they observe a difference in age at autism diagnosis between those vaccinated and not vaccinated or between those vaccinated before or after 18 months of age. These authors also found no differences in autism rates among vaccinated and unvaccinated children when they extended their analysis to include a longer time after MMR exposure or a second dose of MMR [ 6 ]. Also in the United Kingdom, researchers performed a time-trend analysis using the General Practice Research Database—a high-quality, extensively validated electronic medical record with virtually complete vaccination data [ 7 ].

More than 3 million person-years of observation during — confirmed an increase in autism diagnoses despite stable MMR vaccination rates. In California, researchers compared year-specific MMR vaccination rates of kindergarten students with the yearly autism case load of the California Department of Developmental Services during — [ 8 ].

As was observed in the United Kingdom, the increase in the number of autism diagnoses did not correlate with MMR vaccination rates. In Canada, researchers estimated the prevalence of pervasive developmental disorder with respect to MMR vaccination in 27, children from 55 schools in Quebec [ 9 ]. Autism rates increased coincident with a decrease in MMR vaccination rates.

The results were unchanged when both exposure and outcome definitions varied, including a strict diagnosis of autism. In England, researchers performed a cross-sectional study of autistic children and demonstrated no difference in age of first parental concerns or rate of developmental regression by exposure to MMR vaccine [ 10 ]. No association between developmental regression and gastrointestinal symptoms was observed.

In London, an analysis of autistic children used the introduction of MMR to compare vaccinated and unvaccinated cohorts [ 11 ]. The incidence of developmental regression did not differ between cohorts, and the authors observed no difference in the prevalence of gastrointestinal symptoms between vaccinated and unvaccinated autistic children. Retrospective, observational studies Four retrospective, observational studies addressed the relationship between MMR vaccine and autism. In Finland, using national registers, researchers linked hospitalization records to vaccination records in , children vaccinated during — [ 13 ].

Of children hospitalized for autistic disorders, no clustering occurred relative to the time of MMR vaccination. In Denmark, again using a national registry, researchers determined vaccination status and autism diagnosis in , children born during — [ 14 ]. The authors observed no differences in the relative risk of autism between those who did and those who did not receive MMR vaccine. Among autistic children, no relationship between date of vaccination and development of autism was observed.

In metropolitan Atlanta, using a developmental surveillance program, researchers compared autistic children with matched control children [ 15 ]. Vaccination records were obtained from state immunization forms. The authors observed no differences in age at vaccination between autistic and nonautistic children, which suggests that early age of MMR vaccine exposure was not a risk factor for autism.

Prospective observational studies Capitalizing on a long-term vaccination project maintained by the National Board of Health, investigators in Finland performed 2 prospective cohort studies.

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Table 2 Studies that fail to support an association between thimerosal in vaccines and autism. Source Study design Location Stehr-Green et al. Ecological studies Three ecological studies performed in 3 different countries compared the incidence of autism with thimerosal exposure from vaccines.

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In each case, the nationwide removal of thimerosal—which occurred in in Europe and in in the United States—allowed robust comparisons of vaccination with thimerosal-containing and thimerosal-free products, as follows: However, in , a steady increase in the incidence of autism began in both countries and continued through the end of the study period in , despite the removal of thimerosal from vaccines in In Quebec, researchers grouped 27, children from 55 schools by date of birth and estimated thimerosal exposure on the basis of the corresponding Ministry of Health vaccine schedules.

School records were obtained to determine age-specific rates of pervasive developmental disorder [ 9 ]. Thimerosal exposure and pervasive developmental disorder diagnosis were found to be independent variables. Similar to previous analyses, the highest rates of pervasive developmental disorder were found in cohorts exposed to thimerosal-free vaccines.

The results were unchanged when both exposure and outcome definitions varied. Cohort studies Four cohort studies that examined thimerosal exposure and autism have been performed, as follows: They found that the risk of autism did not differ between children vaccinated with thimerosal-containing vaccines and those vaccinated with thimerosal-free vaccines or between children who received greater or lower quantities of thimerosal [ 24 ].

They also found that the rates of autism increased after the removal of thimerosal from all vaccines. The researchers found no relationship between receipt of thimerosal-containing vaccines and autism. In England, researchers prospectively followed 12, children for whom they had complete vaccination records who were born during —, and they found no relationship between early thimerosal exposure and deleterious neurological or psychological outcomes [ 26 ].

In the United Kingdom, researchers evaluated the vaccination records of , children born during —, using the General Practice Research Database, of whom were affected with autism [ 27 ].



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No relationship between thimerosal exposure and autism diagnosis was observed. The notion that children might be receiving too many vaccines too soon and that these vaccines either overwhelm an immature immune system or generate a pathologic, autism-inducing autoimmune response is flawed for several reasons: Vaccines do not overwhelm the immune system.

Although the infant immune system is relatively naive, it is immediately capable of generating a vast array of protective responses; even conservative estimates predict the capacity to respond to thousands of vaccines simultaneously [ 30 ]. Consistent with this theoretical exercise, combinations of vaccines induce immune responses comparable to those given individually [ 31 ].

Also, although the number of recommended childhood vaccines has increased during the past 30 years, with advances in protein chemistry and recombinant DNA technology, the immunologic load has actually decreased.

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The immune response elicited from the vast antigen exposure of unattenuated viral replication supersedes that of even multiple, simultaneous vaccines. Multiple vaccinations do not weaken the immune system. Vaccinated and unvaccinated children do not differ in their susceptibility to infections not prevented by vaccines [ 33 — 35 ]. In other words, vaccination does not suppress the immune system in a clinically relevant manner. However, infections with some vaccine-preventable diseases predispose children to severe, invasive infections with other pathogens [ 36 , 37 ].

Therefore, the available data suggest that vaccines do not weaken the immune system. Autism is not an immune-mediated disease. Unlike autoimmune diseases such as multiple sclerosis, there is no evidence of immune activation or inflammatory lesions in the CNS of people with autism [ 38 ]. In fact, current data suggest that genetic variation in neuronal circuitry that affects synaptic development might in part account for autistic behavior [ 39 ]. Thus, speculation that an exaggerated or inappropriate immune response to vaccination precipitates autism is at variance with current scientific data that address the pathogenesis of autism.

No studies have compared the incidence of autism in vaccinated, unvaccinated, or alternatively vaccinated children i. These studies would be difficult to perform because of the likely differences among these 3 groups in health care seeking behavior and the ethics of experimentally studying children who have not received vaccines. Acknowledgments Potential conflicts of interest. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lack of association between measles virus vaccine and autism with enteropathy: Autism and measles, mumps, and rubella vaccine: Mumps, measles, and rubella vaccine and the incidence of autism recorded by general practitioners: Time trends in autism and in MMR immunization coverage in California.

Pervasive developmental disorders in Montreal, Quebec, Canada: Fombonne E, Chakrabarti S. No evidence for a new variant of measles-mumps-rubella—induced autism. Measles, mumps, and rubella vaccination and bowel problems or developmental regression in children with autism: Do children who become autistic consult more often after MMR vaccination?

Br J Gen Pract. Neurologic disorders after measles-mumps-rubella vaccination.