A toddler’s activity levels\u00a0are\u00a0influenced by genetic differences, with\u00a0some of\u00a0the same genetic\u00a0markers\u00a0also linked to Attention Deficit and\u00a0Hyperactivity Disorder (ADHD),\u00a0according to new research from the University of Surrey.\u00a0<\/p>\n
In the first study of its kind, an international team of scientists, led by Professor Angelica Ronald, analysed data from\u00a0nearly 80,000\u00a0infants from\u00a0multiple\u00a0national and international\u00a0cohort studies, to discover\u00a0the\u00a0genetic differences\u00a0that\u00a0influence toddler\u00a0activity levels.\u00a0Genetic differences (or genetic variation)\u00a0refer\u00a0to the\u00a0differences in DNA sequences between individuals.\u00a0<\/p>\n
Previous\u00a0studies\u00a0indicate\u00a0that toddler\u00a0activity levels\u00a0vary\u00a0widely between children.\u00a0Environmental factors\u00a0are known to\u00a0play a\u00a0role,\u00a0however, this is the first study to\u00a0identify\u00a0the genetic markers involved.\u00a0<\/p>\n
Professor Angelica Ronald,\u00a0lead author of the study and\u00a0Professor of Psychology and Genetics at the University of Surrey, said:\u00a0<\/p>\n
“From 12 to 36 months is\u00a0a very exciting\u00a0time for parents and children,\u00a0with a lot of new skills being learnt. During this time, we know that toddlers vary widely in how much they move around.\u00a0Some children are happy to sit\u00a0still\u00a0whereas\u00a0others\u00a0are\u00a0livelier, they\u00a0run\u00a0around\u00a0and\u00a0move\u00a0a lot.\u00a0Activity levels\u00a0are important and\u00a0likely\u00a0influence\u00a0a\u00a0wide variety of experiences including\u00a0learning,\u00a0exploring the\u00a0wider\u00a0environment, development\u00a0of motor skills\u00a0and\u00a0the type of\u00a0parenting\u00a0that children\u00a0receive.\u00a0<\/p>\n
“We were interested to learn about the underlying biology of\u00a0early activity levels\u00a0and whether these behaviors share some of the same genetic influences that affect\u00a0things\u00a0late in life\u00a0such\u00a0as diagnoses\u00a0of\u00a0ADHD\u00a0and educational\u00a0outcomes.\u00a0Our results can be used to think about how better to\u00a0identify\u00a0young children who would\u00a0benefit\u00a0from early interventions for their ADHD-like\u00a0behaviors.”\u00a0<\/p>\n
The team of scientists were able to map and\u00a0identify\u00a0the specific genetic differences influencing toddler\u00a0activity levels. Ten percent of the variation in toddler activity levels\u00a0can be\u00a0explained by common genetic differences discovered by the researchers.\u00a0The\u00a0genetic markers\u00a0they discovered were found to\u00a0overlap\u00a0strongly\u00a0with\u00a0those\u00a0that influence likelihood of ADHD\u00a0which is diagnosed later in childhood or in adulthood.\u00a0<\/p>\n
As a specific example,\u00a0markers in\u00a0the gene\u00a0RHEBL1\u00a0were\u00a0identified as being\u00a0associated with\u00a0lower\u00a0toddler activity levels.\u00a0These same genetic\u00a0markers\u00a0also\u00a0affect how active the\u00a0RHEBL1\u00a0gene is in the cortex, a major region of the brain. In other words, the same DNA variations that seem to influence\u00a0lower\u00a0toddler\u00a0activity levels also appear to turn up the\u00a0activity of the\u00a0RHEBL1\u00a0gene in this brain region.\u00a0This finding\u00a0opens up\u00a0new avenues for understanding how a child’s early activity levels are shaped by their biology. The findings\u00a0could help scientists better understand the relationship between movement, brain\u00a0development\u00a0and learning.\u00a0<\/p>\n
Anja Hollowell, who was the first author of the study\u00a0and completed\u00a0the work\u00a0while\u00a0at the University of Surrey and Birkbeck,\u00a0and is now based at UCL,\u00a0explained:\u00a0<\/p>\n
“Our findings show that\u00a0very early\u00a0activity levels are influenced by many of the same genetic markers that influence later ADHD. Earlier identification of ADHD would be\u00a0very helpful\u00a0for providing\u00a0timely\u00a0support to children and their families.\u00a0<\/p>\n
“We did not know until now that the genetic basis of ADHD was shared with these early behavioral\u00a0traits.”\u00a0<\/p>\n
As part of the same study, the team also\u00a0discovered\u00a0genetic variants associated with\u00a0other\u00a0key\u00a0toddler\u00a0behaviors, namely,\u00a0sociability,\u00a0emotionality\u00a0and shyness. They\u00a0identified\u00a0multiple genes that were\u00a0associated with these\u00a0behaviors.\u00a0<\/p>\n
Interestingly,\u00a0the genetic markers associated with toddler\u00a0emotionality were\u00a0also\u00a0found to\u00a0be associated with\u00a0neurotic personality traits in adulthood.\u00a0In addition, the genetic\u00a0variation associated with toddler emotionality and with low sociability overlapped with the genetic variation known to\u00a0be associated with\u00a0likelihood of autism.\u00a0<\/p>\n
Professor Ronald\u00a0added:\u00a0<\/p>\n
“For the first time, we have\u00a0identified\u00a0the genetic variation\u00a0associated with\u00a0these early behavioral traits in toddlers.\u00a0Our work\u00a0highlights the\u00a0significance of ‘nature’ in a young child’s\u00a0behavior.\u00a0This complements the\u00a0existing\u00a0research\u00a0on environmental influences on early childhood.\u00a0These new results\u00a0advance\u00a0our understanding of the early pathways\u00a0influencing individual differences in child development.”\u00a0<\/p>\n
This study was published in\u00a0Nature Human behavior.<\/p>\n
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