Study Links Toddler Activity Levels to ADHD Genetic Markers
Genetic differences that affect how active a toddler is may also be associated with attention deficit hyperactivity disorder (ADHD), according to a new study published in the journal Nature Human Behaviour. The research analyzed data from nearly 80,000 infants across multiple international cohort studies, including British and European samples.
ADHD is a neurodevelopmental condition characterized by short attention spans and impulsive, restless behavior. The study found that common genetic variations explain about 10% of the differences in activity levels among toddlers, and these same genetic markers overlap strongly with those that influence the likelihood of developing ADHD later in childhood or adulthood.
Key Genetic Marker Identified
The researchers identified specific genetic markers, including one in the gene RHEBL1, that are linked to lower activity levels in toddlers. Interestingly, the same DNA variations also affect how active the RHEBL1 gene is in the brain's cortex, a major brain region. This suggests that lower toddler activity levels may be influenced by genetic factors that also impact brain function.
First author Anja Hollowell from the universities of Surrey and Birkbeck in the UK stated, "We did not know until now that the genetic basis of ADHD was shared with these early behavioural traits (activity levels displayed as a toddler). Our findings show that very early activity levels are influenced by many of the same genetic markers that influence later ADHD. Earlier identification of ADHD would be very helpful for providing timely support to children and their families."
Implications for Early Intervention
Lead author Angelica Ronald, professor of psychology and genetics at the University of Surrey, emphasized the significance of the study. "From 12 to 36 months is a very exciting time for parents and children, with a lot of new skills being learnt. During this time, we know that toddlers vary widely in how much they move around. Activity levels are important and likely influence a wide variety of experiences including learning, exploring the wider environment, development of motor skills and the type of parenting that children receive."
Ronald added, "For the first time, we have identified the genetic variation associated with these early behavioural traits in toddlers. Our work highlights the significance of 'nature' in a young child's behaviour. This study complements the existing research on environmental influences on early childhood. These new results advance our understanding of the early pathways influencing individual differences in child development."
Future Research Directions
The findings open up new avenues for understanding how a child's early activity levels are shaped by biology and could help scientists better understand the relationship between movement, brain development, and learning. The team hopes that this research will lead to earlier identification of ADHD risk, enabling timely support for children and their families.
