Children of anxious mothers have double the risk of hyperactivity in adolescence
A large study has shown that children of mothers who are anxious during pregnancy and in the first few years of the child's life have twice the risk of having hyperactivity symptoms at age 16. This work is being presented for the first time at the ECNP Congress in Copenhagen.
Scientists know that fetal and early life conditions can have long-term effect on subsequent health. Now a long-term study of more than 3000 children in the Avon Longitudinal Study of Parents and Children (ALSPAC) has shown that maternal anxiety is associated with hyperactivity in their children, although the link with other ADHD symptoms such inattention is more tenuous.
ALSPAC is a long-term project based in Bristol UK, which allows scientists to track how children's health changes over time. The study recorded reported levels of some physical symptoms of anxiety such as sweating, trembling, dizziness, and insomnia in 8727 mothers in the period between early pregnancy and her child reaching 5 years of age.
The researchers were able to classify the mothers' anxiety levels, depending on how often the mothers reported signs of physical anxiety. Very broadly, the women fell into low anxiety, medium anxiety, or high anxiety class.
The researchers then checked how children performed in attention tests (when they reached 8 and a half years of age), and found that there was no difference between children in attention, no matter how anxious the mothers had been. However, testing a larger group of 3199 children at the age of 16 showed that there was a significant difference in hyperactivity symptoms, depending on how anxious the mother had been.
On average a child from a mother who had expressed moderate or high anxiety was around twice as likely to show symptoms of hyperactivity from a mother with low anxiety* Adjusting for social and demographic factors showed a similar correlation**. This means that 11% of the children from 'high anxiety" mothers, and 11% of children from "moderate anxiety" mothers showed symptoms of hyperactivity. Only 5% of children from '"low anxiety" mothers showed hyperactivity symptoms.
Dr. Blanca Bolea, led the study when she was at the University of Bristol. She is now Assistant Professor at the University of Toronto in Canada. She said:
This is an association, so we can't 100% say that anxiety symptoms in pregnancy and early life causes later hyperactivity, other genetic, biological or environmental effects may be at play. However, this idea is supported by studies in animals. We're not sure why this might happen. It could be a that the children are responding to perceived anxiety in the mother, or it could be that there is some biological effect which causes this, for example stress hormones in the placenta having an effect on a developing brain. ADHD is a controversial illness, and there doesn't seem to be any single cause, though we know it can be hereditary. This work shows that maternal anxiety is one factor which is linked to ADHD, but we need some more research to confirm this and other causes"
Commenting, Professor Andreas Reif (University Hospital, Frankfurt) said:
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