Autism is a neurodevelopmental disorder that affects the way the brain develops. It causes difficulty with social skills, communication and other areas of development. Scientists believe that the condition may be caused by a combination of genetic and environmental factors. They believe that certain prenatal factors can increase the risk of autism, including bacterial or viral infections in the mother during pregnancy and older paternal age at conception.
Environmental Factors
Environmental factors that contribute to the development of autism include genetic predispositions, endocrine disrupting chemicals (EDCs), and psychological stress. All of these can alter the way genes function by either directly or indirectly interacting with the DNA. For example, exposure to endocrine-disrupting chemicals during pregnancy can affect the brain’s ability to develop normally. This can lead to a reduction in thyroid hormone signaling, which is important for fetal brain development and could increase the risk of developing ASD later on.
Aside from these direct effects, many EDCs also interact with the DNA by influencing epigenetic mechanisms. These can then exacerbate the underlying gene mutations that cause ASD. One of the best ways to reduce the risk of ASD is to prevent exposure to these toxic chemicals during pregnancy. This is possible with the use of prenatal supplements that can reduce exposure to endocrine-disrupting drugs and help the baby grow properly. These supplements are also safe and affordable.
Genetics
While 自閉症成因 is still largely a disorder caused by environmental factors, there are hundreds of genes that have been linked to autism and can make it more likely for someone to develop the condition. One study of 829 families that included autistic children and their siblings found alterations to parts of noncoding DNA that regulate gene expression. In these regions, the researchers saw large changes, called structural variants, that inverted, duplicated, or deleted parts of the genome.
Another study looked at the genetic contributions of genes that are associated with different neurodevelopmental outcomes, including developmental delay and autism. It found that genes associated with developmental delay tend to be important in early fetal brain development, whereas genes that are associated with autism are more involved in later stages of neuronal development. As genetic research progresses, scientists are discovering more and more ways that different genetic variants affect a person’s risk for autism. These variants can come in the form of epigenetics, sex-linked modifiers, CNVs (chromosomal rearrangements), and double-hit mutations.
Vaccines
Despite a long history of scientific research that has conclusively shown no link between vaccines and autism, many people still believe that vaccines cause the condition. Parents and others have founded organizations that protest what they see as a government/pharmaceutical conspiracy. A British doctor named Andrew Wakefield published a paper in the Lancet in 1998 that claimed that the MMR (measles, mumps, and rubella) vaccine caused intestinal inflammation that lead to autism in children. This theory was quickly embraced by politicians and autism support groups.
A study published in 2004 by scientists from the NIH and Centers for Disease Control found that vaccines did not cause autism. They reviewed all existing studies on the subject. These studies looked at both vaccinated and unvaccinated children, and examined everything from the timing of vaccinations to ingredients in vaccines like thimerosal or aluminum-containing adjuvants. They also looked at other factors that could cause the disorder, including genetics and environmental factors.
Parenting
Parenting is a complex process that affects not only children but also parents themselves. It can enrich and give focus to their lives; generate stress or calm; compete for time with work or leisure; and create combinations of any number of emotions, including happiness, sadness, fulfillment, and anger. Although there is a great deal of controversy about the exact 自閉症成因, one thing that many agree on is that parenting can be an important factor. In the 1940s, Leo Kanner suggested that cold, distant parenting — especially on the part of mothers — could be the cause of autism in children.
Despite this, research in the 1950s, 1960s and 1970s demonstrated that parenting behavior did not appear to contribute to autism. The theory was eventually replaced by a belief that autism was more genetically based. There is a lot of evidence that parenting interventions can have a positive impact on child outcomes. For example, one intervention involving parent-mediated communication skills training seems to be effective in reducing severity of autism symptoms. However, the effects of these interventions are often small and take years to achieve.
Final Word
Autism causes are a complex mix of genetic and environmental factors. Some of the most common genetic causes include chromosomal conditions and birth defects like fragile X syndrome, tuberous sclerosis, or Rett syndrome. While some of these conditions can occur at any point during development, the way they affect brain structure and growth may be linked to the likelihood of developing ASD.
