Causes and Prevalence Rates

What Causes Autism?

You’ll hear a number of theories, some with some very vocal adherents, but the short answer is that there is no definitive answer. Scientists strongly suspect a genetic cause, or perhaps a genetic predisposition that is triggered by something in the environment during neonatal or later development. This lack of clarity about the cause contributes to a considerable amount of speculation and conflicting theories among parents and scientists about the cause or causes of autism.

Although autism was first identified in 1943 (Kanner, 1943), the underlying neurological mechanisms that give rise to this complex disorder are still unclear and remain unknown. The prevailing theory is that autism is a neurological disorder that affects the functioning of the brain. Though much about autism remains a mystery, here are some observations made by researchers:

  • Some people are genetically more susceptible to autism.
  • Individuals with autism seem to have differences in typical brain development, including size, structure, shape, and connectivity.
  • Serotonin levels are abnormal in some people with autism.

The effort to find the cause of autism continues with investigations into a number of theories related to our genes, environmental factors, and the immune system.

What About Autism and Vaccines?

Most discussion about the cause or causes of autism, especially in media reports, invariably touches on the subject of vaccines and autism. Indeed, a number of parents of children with autism believe that there is a link between autism and the MMR vaccine (injection of a mixture of three live attenuated viruses for immunization against measles, mumps, and rubella) and that the vaccine, in fact, caused the onset of autism. Despite the strongly held beliefs of proponents of the vaccine theory, there is no scientific proof that the MMR or any vaccines cause autism.

There is a correlation in time, however. The age for autism diagnosis is normally between years 1 and 3, whereas children are vaccinated around the age of 2. With no other explanation for the onset of autism, this correlation often leads parents to link the development of autism symptoms to the effects of the MMR vaccine. As a result of those concerns and the advocacy of many parents and parent groups, there is ongoing research that is examining environmental factors, to include vaccines, as they may relate to autism. At present, however, there is no evidence that a link between autism and vaccines exists, and it is important to note that vaccines help protect and strengthen the body’s immune system.

What is the Prevalence of Autism?

Autism Spectrum Disorder (ASD) is found in all cultures and across all socio-economic groups. In the past 40 years, the prevalence rate of Autism has skyrocketed. In 2018, the Centers for Disease and Control Prevention (CDC) reported an estimated 1 out of every 59 children have ASD.

Why the increase? No one knows for sure. Some epidemiologists point to an increasing awareness of the disorder as a key contributing factor. Others consider the potential impact of environmental factors (e.g., toxins) as a contributing cause. As more research is conducted, this question may soon be answered.

According to the CDC, boys are 4 times more likely to be diagnosed with ASD than girls (2018). Some experts have theorized that girls are more likely to develop compensatory social mechanisms to mask their symptoms, and that this may explain this ratio.

What is the Prevalence Rate Among Military Families?

Research conducted by the CDC shows that there are varying prevalence rates of ASD across different geographic locales. The same variability can be observed among military dependents. There were reportedly 1,177,190 military dependent children according to a DoD study (2005), which meant that one out of 88 children of active duty military service members had autism. In 2006, the prevalence rate of autism among the general surveilled US population was one out of every 110 children, though that estimate has since changed.

When one considers that those studied were more often service members in the junior ranks and the youngest parents (i.e., the families most vulnerable to the additional financial burden that accompanies having a child with autism), the implications for and potential impact on military healthcare are significant.

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