The rates of autism spectrum disorders

Amanda McKinney is a physician with a passion for Lifestyle Medicine and environmental issues who recognizes the intimate relationship between our food and the health of both humans and the planet. She is a Fellow of the American College of Lifestyle Medicine and is a Certified Physician Executive. She founded the Institute of Human and Planetary Health to improve human health by transforming medical education and healthcare delivery and creating healthy, resilient communities. Creating a culture of healthy food, grown sustainably, will have a positive impact on planetary health as well.

The rates of autism spectrum disorders (ASD) have risen to epidemic levels. In 1981, it was 1 in 10,000. In 2000, it was 1 in 150, and our most recent estimate is 1 in 68. If the current rate of increase continues, half of all children will be considered to have an ASD by the year 2050. A debate has ensued regarding whether the incidence of autism spectrum disorders is falsely elevated because of changes in the way we diagnose these children, or whether there is some environmental factor that is causing an actual real rise in new cases. According to the Centers for Disease Control, there have been no changes in the criteria used to diagnose or treat cases of ASD since 2012, yet there has been a 30% increase in the number of cases since then. The rate increased from 1:88 in 2012 to 1:68 in 2014.

There are many factors that can contribute to the development of autism. Like most chronic disease, it is partly genetic but mostly it is related to epigenetics. Epigenetics is the science of how our genes are expressed, or turned on and off, by our exposures. Pesticides and other environmental pollutants have been implicated as contributing to the development of ASDs in those already genetically susceptible, but what we know is that anything that causes inflammation in expectant mothers can result in an autistic child.

For instance, infections like influenza and rubella or any other infection that results in a fever that lasts 7 days or more in pregnancy increases the risk of having an autistic child by 2- to 4-fold.

Chronic diseases in expectant mothers that are associated with chronic inflammation like obesity and diabetes also pose an increased risk. Obesity during pregnancy increases the risk of having a child with autism 1.6 times, and diabetes during pregnancy doubles the risk.  Higher consumption of maternal dietary fat and low consumption of preconception folate, found in fruits, vegetables, and legumes, are both associated with an increased risk of having a child with autism as well.

Of the reproductive-aged population (18-39 year olds) in the US, 54 are overweight or obese. This, combined with the fact that approximately 55% of US adults are diabetic or pre-diabetic, is enough to explain at least part of the increase in ASD.

In the case of ASD, prevention is the key and targeting the inflammation is the key to prevention. Eating a diet based on whole, plant foods reduces inflammation and prevents and reverses diabetes and obesity. In addition, because plant foods are lower in pesticides than animal foods, even when conventionally rather than organically grown,  eating a plant-based diet has been shown to reduce exposure to all sorts of toxic environmental pollutants like pesticides and dioxins.