According to the CDC (Center for Disease Control and Prevention: Center for disease control and prevention) 1 in 59 children aged 8 years, the peak age for case identification, has a diagnosis within the Autism Spectrum Disorder ( TORCH).
Autism and its growth
According to these data, the estimated number of cases went from 1 in 2,500 births in 1990 to 1 in 150 in the following decade. Already in 2008 an astonishing fact was published that brought to light the prevalence of 1 autistic child in 88.
This growth in recent years has led professionals to investigate its causes, without finding clear and unanimous reasons to justify it.
More and better ASD diagnoses
The working group led by Peter Bearman from Columbia University’s Faculty of Arts and Sciences (New York, USA) explains this growth as a result of better diagnosis. Since 1987, the expansion of the diagnostic criteria and their clarification have given rise to more targeted and exact evaluations, which avoid the old erroneous and temporary attempts that were made with different cases of ASD. According to them, this change could explain 26% of the extra cases in recent times.
Social work and the diagnosis of autism
Along the same lines, the social work that has been done to increase the awareness of parents, teachers and specialists has led to refining observation and wanting to seek answers when something is out of the norm. Thanks to this and the greater access of the middle class to the field of health, it has allowed them to have greater and better access to diagnoses, facilitating improvement and interdisciplinary work. According to Bearman and his team, this change would explain 16% of the increase in cases today.
Diversity of possible factors in the diagnosis of autism
After having made the calculation explained by these researchers, we observe that only 42% of the increase produced is explained by these factors, leaving the remaining 58% without any clear explanation and generating a multitude of hypotheses that go from genetics, the appearance of the diagnosis by the implementation of vaccines, the interval between births, the physical exhaustion of the mother in front of the second birth, obesity, diabetes or hypertension of the mother and other very diverse environmental factors.
Biology and the environment, keys in the diagnosis of autism
In the genetic field, it is considered that the growth of the ASD population is due to the quality of the genes that we transmit to our children. Unlike previous times, we currently generate few offspring, breeding at a much older age than in the past. This means that we transfer genes that can have greater accumulated damage. In this sense, King, Fountain, Dakhlallah and Bearman estimated that the older age of the parents at the time of pregnancy could explain up to 11% of the increase in ASD cases.
However, studies like this one, little contrasted and replicated, contribute, more than advances to the knowledge of autism, a greater stigmatization for parents and autistic people. Likewise, it considers the neurological structure of autism as a result of damage to brain development and not as a configuration other than the normotypical one.
Environmental factors and genetic alterations
What has been observed is that there is a certain genetic coherence that could generate clues to understand this condition. In this sense, the investigations carried out with twins have made it possible to clarify this relationship: When a person is diagnosed within the spectrum of autism, the probability that his/her twin brother/sister will have the same diagnosis is 70%. When we talk about twins, this probability drops to 35%; reducing between 3 and 14% in the second child after a first autistic. In other words, there could potentially be a part of genetic inheritance in the field of autism, although this vision cannot yet be considered definitive.
Based on environmentalist positions, the explanations that are repeated most often refer to the effects of the post-industrial world where we live as responsible for the new cases of autism. In this sense, a polluted environment full of chemicals could favor the appearance of certain complications in the current population. Two recent studies published in the Archives of General Psychiatry and Environmental Health Perspectives indicate that exposure to air pollution caused by traffic both during pregnancy and during the first year of life could directly affect the increase in cases of autism. in recent years. To be sure, these data could not clearly demonstrate that after intense exposure to pollution “autism is directly generated”, so the results are more advertising than conclusive.
Along the same lines, studies by Heather Volk and her group at the University of Southern California School of Medicine in 2011 observed that autism was more frequent in mothers who during their pregnancy lived near communication routes with a heavy traffic than in those with addresses further away from heavy traffic. In any case, the studies were not conclusive either, but rather anecdotal, but they made it possible to begin to consider the impact of polluting substances in the environment on brain development in general.