In the 1943, Leo Kanner, a doctor at Johns Hopkins University, described infantile autism as a group of “emotional or social problems.” He classified this as a neurodevelopmental disorder, and studies since had broadened our understanding of autism and its presumed causes. While there is speculation as to its origins, diagnostical research and statistical data have identified genetics as a culprit. According to the U.S. Department of Health and Human Services, “More than 100 genes on different chromosomes may be involved in causing ASD, to different degrees”.
In an article published by Phillip J. Landrigan, a pediatrician at Boston College, “indirect research” may show a correlation between chemicals and neurodevelopment. According to Landrigan, “the most powerful proof-of-concept evidence derives from studies linking autism to exposures in early pregnancy – thalidomide, misoprostol, and valproic acid; maternal rubella infection; and the organophosphate insecticide, chlorpyrifos.” Landrigan says that there is no credible research showing vaccines are a causative agent. A study led by Landrigan and his colleagues determined a “unique susceptibility” in children to pollutants and pesticides.
Though initiatives have been implemented to reduce childhood exposure to dangerous pollutants such as led, insecticides are prevalent in our agricultural industry in the United States. According to the United States Geological Survey, one-billion pounds of insecticides are used in the United States annually. Besides agricultural farming practices, these contaminants are also in our water sources, according to USGS.
Agricultural guidelines such as the Food Quality Protection Act are implemented and enforced, and strict standards of the use of pesticides are observed prior to harvesting and consumption of crops. According to the EPA, “the fruits and vegetables our children are eating are safer than ever.” The EPA evaluates new and existing pesticides every fifteen years and assesses their effects on consumer health.
This raises the question: are the chemicals we are being exposed to in our daily living causing increased instances of infantile neurodevelopment diagnosis? According to the Center for Disease Control, the instances of autism have increased since 2000. Reportedly, about one per every one-hundred-fifty children showed the signs and symptoms of autism in 2000. A survey conducted in 2018 indicated that an astonishing one in every forty-four children presented with ASD.
Could this be a case of over- diagnosis within our medical community, or are the incidences increasing at an alarming rate? These numbers, though concerning, could result from increased awareness. Educational screening assessments and diagnostic testing have come a long way in the last twenty years, and as information becomes available, the indicators or ASD are more easily recognized.
Besides the scientific evidence correlating genetic factors and toxic exposures, the association of media usage has also been examined in relation to ASD patients. According to research published by the National Library of Medicine, “16 studies met the inclusion criteria. The studies support the view that children and adolescents with ASD are exposed to more screen time than their typically developing peers or other clinical groups and that the exposure starts at a younger age.”
Does socioeconomic status play a role in autism development? Another article published by the National Library of Medicine cited a study conducted in the United Kingdom. According to data comprising over thirteen-thousand children born between 2007-2011, children born to mothers with a higher-level education showed an increased incidence of autism diagnosis. However, the article addresses the question of a resource gap, inequality, and the problem of underdiagnosis. No definitive correlative evidence suggests a relationship between income level and ASD.
Maternal age is also a factor. According to an epidemiological study published in Autism Research studied the parental age of over twelve-thousand children born between 1990-1999 in California. The data showed that mothers over the age of forty had a fifty-one percent higher risk of having a child with autism than mothers aged twenty-five to twenty-nine, and a seventy-seven percent higher risk than mothers under the age of twenty-five.
Statistics show that maternal age has also increased. Another California study showed a “three-fold increase in the number of births to women aged 40 to 44 between 1982 and 2004.” Could this result from a shift in gender roles and societal norms? Perhaps women of childbearing age are placing greater emphasis on their career and education paths, accounting for the increases in maternal ages shown in statistical data.
Paternal age factors were only a risk factor when the mother is over the age of thirty. Prolonged labor, premature delivery, and lower APGAR scores have also been proven to increase the risk of autism; all of which were more prevalent in mothers over the age of thirty-five. Further analysis is underway to examine the association between maternal age and possibly prolonged exposure to toxic substances.
Research examining the gestational period suggests a link between the mother’s immune system and the developing fetus. During the gestational period, the mother’s IgG antibodies transfer to the fetus via the placental barrier, providing the newborn with immunity until the infant can develop his/her own within the first six months of life. However, with maternal autoimmunity, the antibodies can interfere with fetal development, resulting in developmental defects. While they proved some of these defects transient, others are permanent.
Neuroplasticity and cognitive development have made leaps and bounds in their research and statistical data, and proven effective in understanding the pathophysiology of conditions like autism spectrum disorder and others. With increased diagnostics, therapies and resources, treating ASD and other associated diagnosis can become more specialized and, hopefully, more effective in the future.