Rare pregnancy infections can triple the risk of autism: Study

A major Swedish study of 37 million people has found that rare TORCH infections passed from a pregnant woman to the fetus are linked to much higher risks of autism and intellectual disability later in lifeAccording to the study on the website ScienceDaily children with a congenital TORCH infection were about three times more likely to be diagnosed with autism more than seven times more likely to have an intellectual disability and up to 30 times more likely to have severe to profound intellectual disabilityRare infections that can pass from a pregnant woman to a developing fetus are associated with higher risks of autism and intellectual disability later in childhood according to a large study from Karolinska Institutet published in JAMA PediatricsIt is important to emphasise that it is unusual for these infections to be transmitted from mother to child They account for a very small proportion of all cases of autism in the population but for those children who are actually affected we see a clearly elevated risk of both autism and intellectual disability says Renee Gardner a researcher at the Department of Global Public Health at Karolinska Institutet who contributed to the study as quoted by ScienceDailyThe research focused on a group known as TORCH infections This category includes among others cytomegalovirus rubella toxoplasmosis and herpesvirus While most common infections do not directly reach a developing fetus these pathogens can sometimes cross the placenta and cause a congenital infectionThe researchers examined health and education records for 37 million people born in Sweden between 1987 and 2021 Among this population 975 people had been diagnosed with a congenital TORCH infectionParticipants were followed for as long as three decades allowing the team to investigate whether these infections were associated with later neurodevelopmental diagnoses and educational outcomesChildren with a congenital TORCH infection were about three times more likely to later be diagnosed with autism than those without an infection Their likelihood of receiving an intellectual disability diagnosis was more than seven times higherFor severe to profound intellectual disability the difference was even larger with the risk rising as much as 30foldThose figures represent substantial increases in relative risk but congenital TORCH infections are rare As a result they account for only a small proportion of autism and intellectual disability cases across the populationThe researchers estimate that congenital TORCH infections may be associated with about 12 per cent of severe intellectual disability cases in Sweden They estimate that about 0034 per cent of autism cases in the country can be attributed to these infections as per the websiteAcircAt the individual level however the researchers estimate that roughly one in five children born with a TORCH infection may later develop autismIt has long been known that these infections can cause intellectual disability However the link to autism has been less clear in previous research which has often been based on small patient groups This study is the largest to date in this field and is based on national register data covering almost the entire population of Sweden says Hugo Sjoqvist a PhD student and lead author of the study as quoted by ScienceDaily websiteThe researchers also used sibling comparisons to investigate whether the findings might instead be explained by characteristics shared within familiesThey compared children who had experienced a TORCH infection with their own siblings who had not The pattern remained similar in these comparisons suggesting that shared family factors alone are unlikely to explain the associationsThe researchers did not identify clear links between congenital TORCH infections and other neuropsychiatric conditions including ADHD or obsessivecompulsive disorderThey did however find differences in school performance Even among children who were not diagnosed with autism or an intellectual disability those with a congenital TORCH infection received lower grades on average than children without an infectionOur results suggest that certain infections transmitted to the fetus during pregnancy may have longterm effects on brain development Although these congenital infections are rare some of them can be prevented which makes them important from a public health perspective says Renee GardnerThe researchers say the findings highlight the importance of preventing infections that can be transmitted to a fetus during pregnancyRubella is one example of how prevention can make a major difference The infection has virtually disappeared in Sweden since national vaccination programs were introducedAccording to the researchers maintaining vaccination programs and other preventive measures remains important for reducing infections that can pass from a pregnant woman to a developing fetusThis story has been sourced from a third party syndicated 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