The Headline:
“A prenatal screening test for autism comes closer today,” says The Guardian. It reports that scientists have found links between high testosterone levels in the womb and autistic traits in children. It says this could lead to tests that can identify autistic children before birth.
NHS Choices says that:
This study indicates an association between higher levels of testosterone in the womb and levels of autistic traits at age six to 10 years.
There are a number of points to consider:
- As the authors acknowledge, the association between testosterone levels and autistic traits does not necessarily mean that high levels of testosterone in the womb directly “cause” an increase in autistic traits. Other factors could have an effect. For example, genetic variations might affect both the levels of testosterone in the womb and levels of autistic traits.
- The samples of amniotic fluid tested were taken at different points in pregnancies, and at different times of day. As testosterone levels are likely to fluctuate over time, it is unclear whether one measurement of testosterone is representative of the foetus’ overall exposure to testosterone.
- Women who undergo routine amniocentesis are often older than the general childbearing population. The average age of women in this study was 35 years old. Although the researchers took maternal age into account, these results may not be representative of younger pregnant women.
- None of the children in this study had autism, therefore the authors note that “caution needs to be taken when extrapolating these results to individuals with a formal diagnosis of [autistic spectrum conditions]”. They report that they are currently working on obtaining a larger sample so that they can determine whether their results apply to children with autistic spectrum conditions.
- The current sample of 235 children was still relatively small. When considering that there was only a 52% response rate among those who were sent the questionnaires, the children may not be representative of the whole group. For example, some parents who had concerns about their child’s development may have felt less inclined to answer a questionnaire about it than those who were happy with their child’s level of development.
Although many newspapers describe the potential for a prenatal test for autism, the authors did not aim to develop such a test. Instead, their aim was to further understand how testosterone may affect development of autistic traits.
Even if such a test were possible, it is important to note that this would be a screening test and not a definitive diagnostic test, i.e. it would identify foetuses more or less likely to develop autism rather than identify those who would definitely go on to develop autism.
Screening tests are rarely 100% accurate, and the many ethical issues surrounding prenatal screening for risk of autism would need to be debated before any test could be offered. Also, there are currently no ways to prevent a child from developing autism. Therefore, it is unclear whether identifying children at greater risk of autism would benefit the child or the parents.
Links to the Headlines:
Disorder linked to high levels of testosterone in womb. The Guardian, January 12 2009
Womb test for autism. Daily Mirror, January 12 2009
If we screen out autism we run the risk of losing genius, too. The Times, January 12 2009
New research raises possibility of prenatal screening for autism. The Daily Telegraph, January 12 2009
