If you have an older grandfather, or your mother was abused in her youth, you are more likely to develop autism during childhood. This is according to two studies published last month in the Journal of the American Medical Association (JAMA) Psychiatry, which add to a growing body of family wellness research indicating that hereditary and environmental influences on autism risk most likely reach across multiple generations.
For the first study, researchers analysed the national records of nearly 6,000 Swedish-born people with autism and 31,000 healthy controls, dating as far back as 1932. The results of this study were that, compared to men who had children when they were age 20-24, older fathers (being over the age of 50 when they had a daughter) were 1.79 times more likely to have a grandchild with autism. If men in this age category had a son, they were discovered to be 1.67 times more likely to have a grandchild with autism.
The team of researchers came from King’s College London’s Institute of Psychiatry, the Karolinska Institutet in Sweden and the Queensland Brain Institute in Australia. According to Emma Frans, lead author of the study, paternal age is already a known risk factor for autism, but ‘this study goes beyond that and suggests that older grandpaternal age is also a risk factor for autism, suggesting that risk factors for autism can build up through generations.’
Co-author Avi Reichenberg, added that though the increased risk was “small,” the results of the study are still ‘important in understanding the complex way in which autism develops.’ He said, ‘We tend to think in terms of the here and now when we talk about the effect of the environment on our genome. For the first time in psychiatry, we show that your father’s and grandfather’s lifestyle choices can affect you.’
Based on data from the US Nurses’ Health Study II, the second study was carried out by researchers at the Harvard School of Public Health (HSPH). The researchers analysed the records of more than 52,000 mothers of children without autism and 451 mothers of children with autism, which affects the wellbeing of every one in 88 in the United States and about one in 100 in Britain.
The study’s researchers commented, ‘Notably, women exposed to the highest level of physical and emotional abuse, comprising one-quarter of the women in our study, were at 61.1 percent elevated risk for having a child with autism compared with women not exposed to abuse. The findings ‘point to a “completely new risk factor for autism,’ said lead author Andrea Roberts, research associate in the HSPH Department of Social and Behavioral Sciences. ‘Further research to understand how a woman’s experience of abuse is associated with autism in her children may help us better understand the causes of autism and identify preventable risk factors,’ she added.
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