Summary: While there is a clear genetic link between young mothers and ADHD in their children, the association is not necessarily causal.
Source: University of South Australia
Young mothers have a greater chance of having a child with attention deficit hyperactivity disorder (ADHD) according to new research from the University of South Australia.
Published in Nature’s Scientific Reports, the research explored the genetic relationship between female reproductive traits and key psychiatric disorders, finding that the genetic risk of ADHD in children was strongly associated with early maternal age at first birth, particular for women younger than 20.
In Australia, ADHD affects one in 20 people. ADHD is a complex neurodevelopmental disorder which impacts a person’s ability to exert age-appropriate self-control. Characterised by persistent patterns of inattentive, impulsive, and sometimes hyperactive behaviour, individuals find it hard to focus, concentrate, and regulate their emotions.
Using genetic data of 220,685 women via the UK Biobank, the study examined genetic correlations between five female reproductive traits (age at first birth, age at first sexual intercourse, age at first occurrence of menstruation, age at menopause, and number of live births) and six common psychiatric disorders (ADHD, autism, eating disorders, depression, bipolar disorder and schizophrenia).
UniSA researcher, Associate Professor Hong Lee says the findings could help improve reproductive health in women and deliver better outcomes for their children.
“Young mums can have it tough, especially as they’re adjusting to becoming a parent while they’re still young themselves,” Assoc Prof Lee says.
“By understanding the links between becoming a mother at a young age and having a child with ADHD, we’re able to better educate and support families sooner.”
“The approach is twofold. Firstly, we’re able to inform young women about the high genetic risk of having a child with ADHD if they give birth at a young age. This may caution and prevent them from giving birth at an immature age, which not only improves their reproductive health but also the maternal environment for their baby.”
“Secondly, we’re able to educate young mothers about the features of ADHD, such as impulsivity and inattentive behaviours, which may help mothers better recognise the condition in their child and seek treatment sooner than later.”
“ADHD is treatable, but early diagnosis and interventions are key to a successful outcome.”
Assoc Prof Lee says while the findings are significant, there are some latent complexities.
“It’s important to understand that while there is a clear genetic link between ADHD and young mothers, this is not necessarily a causal relationship.”
“ADHD is a highly heritable disorder which means that a young mother may also have the genes affecting ADHD risk which is then inherited by her child.”
“Knowing a woman has a genetic predisposition for ADHD can be recorded in her family medical history then used to monitor her health and the health of her offspring. In this way, we’re able to ensure both mother and baby receive the support and help they need.”
University of South Australia
Annabel Mansfield – University of South Australia
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Original Research: Open access
“The genetic relationship between female reproductive traits and six psychiatric disorders”. Guiyan Ni, Azmeraw T. Amare, Xuan Zhou, Natalie Mills, Jacob Gratten & S. Hong Lee.
Scientific Reports doi:10.1038/s41598-019-48403-x.
The genetic relationship between female reproductive traits and six psychiatric disorders
Female reproductive behaviours have important implications for evolutionary fitness and health of offspring. Here we used the second release of UK Biobank data (N = 220,685) to evaluate the association between five female reproductive traits and polygenic risk scores (PRS) projected from genome-wide association study summary statistics of six psychiatric disorders (N = 429,178). We found that the PRS of attention-deficit/hyperactivity disorder (ADHD) were strongly associated with age at first birth (AFB) (genetic correlation of −0.68 ± 0.03), age at first sexual intercourse (AFS) (−0.56 ± 0.03), number of live births (NLB) (0.36 ± 0.04) and age at menopause (−0.27 ± 0.04). There were also robustly significant associations between the PRS of eating disorder (ED) and AFB (0.35 ± 0.06), ED and AFS (0.19 ± 0.06), major depressive disorder (MDD) and AFB (−0.27 ± 0.07), MDD and AFS (−0.27 ± 0.03) and schizophrenia and AFS (−0.10 ± 0.03). These associations were mostly explained by pleiotropic effects and there was little evidence of causal relationships. Our findings can potentially help improve reproductive health in women, hence better child outcomes. Our findings also lend partial support to the evolutionary hypothesis that causal mutations underlying psychiatric disorders have positive effects on reproductive success.