A large study showed that hyperactivity symptoms can occur twice as often in children of anxious mothers. This work will be presented at the ECNP Congress, Copenhagen, for the first-time.
Scientists know that early life and foetus conditions can have a long-lasting impact on future health. A long-term study of over 3000 children in the Avon Longitudinal Study of Parents and Children, ALSPAC, has shown that hyperactivity in children caused by maternal anxiety is linked to ADHD symptoms like inattention.
ALSPAC is a long-term, UK-based project that allows scientists to track the changes in children’s health over time. The study measured the levels of some symptoms of anxiety, such as dizziness, sweating, trembling, dizziness, and insomnia, in 8727 mothers during the time period between early pregnancy, and when their child reached 5 years old.
Researchers were able to classify mothers’ anxiety levels based on the frequency with which they reported symptoms of physical anxiety. The women were classified as low, medium, and high anxiety.
The researchers then tested how children performed in attention tests when they were 8 and a quarter years old. They found no difference in children’s performance in attention tests, regardless of how anxious their mothers were. However, testing a larger sample of 3199 children at 16 years old revealed that hyperactivity symptoms varied depending on the anxiety of the mothers.
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% children of mothers with high anxiety and 11% from mothers with moderate anxiety showed signs of hyperactivity. Hyperactivity symptoms were only seen in 5% of children whose mothers are ‘low anxiety’.
Dr. Blanca Bolea was the lead researcher during her time at the University of Bristol. She is now Assistant Professor at University of Toronto, Canada. She said:
“This is the very first study that has shown that anxiety can be linked to hyperactivity in later years of life. However, inattention is not associated with it. One possibility is that ADHD symptoms are linked to the mother’s anxiety but not all. It shows that stress experienced by a mother can manifest in her child almost a generation later. It is worth noting, however, that all mothers reported experiencing an increase in anxiety during pregnancy. We found that around 28% of the women tested had high or medium anxiety. We tested 3199 children for hyperactivity and found that 224 of them had signs of hyperactivity. The rate of hyperactivity was more than twice as high if the mother suffered from high or medium anxiety.
This is a correlation, so while we can’t say for certain that anxiety symptoms during pregnancy and early life cause later hyperactivity, we can speculate that other genetic, biological, and environmental factors may be involved. This idea has been supported by animal studies. We don’t know why this might occur. It could be that the children are reacting to the mother’s anxiety. Or it could be that there is a biological cause. For example, stress hormones in the placenta could have an effect on the developing brain. ADHD is a controversial condition. Although there doesn’t seem a single cause, we know that it can be hereditary. This research has shown that ADHD is associated with maternal anxiety. However, more research is needed to confirm this as well as other causes.
Professor Andreas Reif (University Hospital Frankfurt), commented:
“This is a fascinating study, especially because of its longitudinal and transgenerational natures and large sample size. As with any study of this design one must be careful not to confuse association with causation. The genetic correlation between ADHD and anxious traits is well-known (Demontis and colleagues 2019, 2019). This finding could be indicative of shared genetic influences. It is important to note that this study does not focus on ADHD or anxiety disorders, but on traits related to these disorders. These data, however, further support the emerging picture that ADHD/hyperactivity, anxiety, and bipolar disorder (Meier et.al., Br J Psychiat 2018,) are connected.
*(OR=2.27,p<0.001 for the class with moderate anxiety and OR=2.23, p=0.003 for the class with high anxiety).
** (OR=2.09, p<0.001 for moderate anxiety, and OR=1.90, p=0.023 for high anxiety).