Impulsive behaviour in adults could be linked to stressful experiences during early life, according to new research published in the Proceedings of the Royal Society B.

The study, led by experts from Newcastle University, UK, has found for the first time a link between cellular changes associated with early-life stress, and risk-taking in adults.

Studying starlings, the team found those birds exposed to greater stress in the nest went on to develop shorter telomeres – biomarkers used to predict future life expectancy – and also had a stronger preference for immediate rather than delayed rewards as adults.

The team believe this sheds further light on how childhood experiences can influence biological development, and say this study goes someway to explain why people who have suffered during childhood are more likely to display impulsive behaviour.

And it highlights the importance of early intervention to support children and remove them from stressful and potentially damaging situations.

Professor Melissa Bateson, based in the Institute of Neuroscience at Newcastle University, explains: “This is all about survival.  Animals that suffer stress in early life are likely to be weaker and less healthy and will therefore prioritise immediate survival over long-term benefits.

“What we have demonstrated here is the biological link between impulsive, short-term decision making and early-life experiences.

“People who have experienced extreme adversity during childhood such as abuse or neglect are more likely to demonstrate impulsive behaviours such as gambling in later life and we believe this study goes some way to explaining why that might be.”

Telomeres - markers of bad experiences 

Telomeres are DNA ‘caps’ found on chromosomes that shorten with age.  Stress-induced damage to these telomeres has been found to be an important factor in the aging process and shortening of telomeres has been shown to increase the risk of disease and premature death.

Starlings can live for up to 20 years and are often used to understand complex behaviours.

By placing chicks into broods of different sizes – where those from a large brood experienced greater stress than fledglings taken from a nest of just one or two chicks – the team were able to experimentally alter the rate of telomere shortening.

Testing the birds’ behaviour 14 months later, the team gave the starlings two choices – a feeder that supplied a small, immediate reward, or one which gave five rewards but only after a short delay.

“Birds whose telomeres had shortened more during early life, as well as birds who were currently hungrier, had a greater preference for the more immediate rewards,” explains Professor Bateson.

“Why would you plan for the future when you don’t know if you’ll make it through to the next day?

“Our findings show that what happens to a starling in the first two weeks of its life has a lasting effect on its telomeres and this in turn predicts adult decision making.

“This means shorter telomeres are markers of bad experiences, and bad experiences predispose adults to taking more risks.

“If, as we believe, this is the same in humans as in other animals then it demonstrates the huge impact that early intervention can have on peoples’ future lives.”

Source information: Bateson, M. et al, “Developmental telomere attrition predicts impulsive decision making in adult starlings”.  Proceedings of the Royal Society B

The study was funded by the Biotechnology and Biomedical Sciences Research Council and the European Research Council

published on: 3 December 2014