What causes autism? Mostly genetics, according to new study
Posted on July 21, 2019 by Ann
For a long time, we have been trying to figure out what causes autism. Textbook descriptions of autism usually state that autism can be caused by a variety of or a combination of genetic and environmental factors, but from the perspective of a caregiver trying to find out more about it, such statements can be a little vague.
Just last week on 17 July 2019, researchers from 7 countries published the largest population-based multinational cohort study to investigate the origins of autism, and the results show that approximately 80% of autism risk is hereditary.
The researchers used national health registries to study the data on over 2 million people born between 1998 and 2011 in 5 countries (Denmark, Finland, Sweden, Israel and Western Australia). Of these, 22,156 individuals were diagnosed with autism. The data sources include 3-generational family linkages (which includes family members such as siblings and cousins). The data followed all participants from birth up to the age 16 years old.
The researchers analysed the data for the contribution of various genetic and nongenetic factors to ASD risks. In particular, they calculated the risk of these possible causes: additive genetic (heritability), maternal effects, shared environmental effects, and non-shared environmental effects.
While there were some slight variations across different countries, authors concluded that, in general, the results provide the strongest evidence to their knowledge to date that:
1. The majority of risk for ASD is from genetic factors (~80%).
2. This is followed by non-shared environment effects.
3. There is little evidence for maternal or shared environmental effects.
This study is significant because it provides statistical evidence and insight to the causes of autism. In the words of the authors, “The current study results provide the strongest evidence to our knowledge to date that the majority of risk for ASD is from genetic factors.”
Such a conclusion will surely have an impact on how we think about autism, and how we manage it. What are some specific implications? Stay tuned for our next article on this topic.