Hair samples may help predict mental illness in children

Researchers have discovered the potential to use hair samples to investigate whether a young person is at risk of developing mental illness later in life.

In a study in the journal Psychoneuroendocrinology, the University of Melbourne team measured the level of cortisol in children’s hair, along with traumatic events experienced.

“We know the experience of trauma can disrupt the production of cortisol,” explains lead author Julian Simmons. “And there is a strong link between cortisol dys-regulation and the onset of mental health disorders like anxiety and depression.”

Cortisol is often referred to as the ‘stress’ hormone. It plays a complex and wide-ranging role in the human stress and arousal response and is also central to glucose availability, blood pressure and immune function. Cortisol is laid down in the hair as it grows, at a rate of approximately one centimetre per month.

“Because cortisol varies so much during the day and is susceptible to lots of different influences, traditionally it has been very difficult to measure accurately,” Dr Simmons explains.

Hair samples provide an historic measure, in the order of months – it is a much more stable process than traditional collection methods like saliva samples, and very easy to collect.

But determining the level of trauma an individual has experienced is just the first step in predicting those at risk of mental illness. While some people may experience trauma and cortisol dys-regulation, they may never go on to experience mental ill health, while others will.

“At the moment we don’t fully understand the mechanisms that lead some people to developing mental illness after experiencing trauma, while others don’t,” says Dr Simmons.

While still in the early stages, researchers know the experience of trauma and hair cortisol levels are linked, suggesting traumatic events lead to longer term alterations in hormone function.

The research is part of the Murdoch Childrens Research Institute’s Childhood to Adolescence Study (known as CATS), and has selected 128 children to track in relation to how brain development and hormonal profiles relate to mental health.

The study, known as iCATS, is focused on the development of Melbourne-based children and adolescents, with the aim of ultimately being able to more accurately identify at risk young people before the onset of mental illness.

This first round of research happened when the participants were nine years old, and researchers will follow families each year until the children are around 16, covering the peak age of onset for mental health disorders.

“We know certain conditions are protective for children’s later mental health, including good boundaries and at least one, consistent, loving adult figure, but much remains to be determined as to the underlying neural mechanisms that mean one child experiences mental ill health and another does not,” explains Dr Simmons.

Neurobiology offers the best avenue for accurately identifying children most at risk of developing mental health disorders, says Dr Simmons, and therefore those that would benefit most from early intervention.

The study provides the opportunity to build on the team’s existing research, which has shown varied forms of trauma can lead to changes in brain development and increased rates of depression through adolescence and beyond.

“Our previous work with families in the laboratory revealed that when parents demonstrate what most of us would consider mild aggression during what was meant to be a positive interaction with their child, it predicted increased rates of depression through adolescence,” explains Dr Simmons.

“Parental aggression during a relatively high conflict interaction, such as discussing room tidying or bedtimes, did not show this relationship.

Rather, it seems that responding to children out of context, such as snapping at them when they’re trying to be playful, is what may be harmful.

“These response patterns could reflect parents’ inability to regulate their own stress in interacting with their child,” he says.

Dr Simmons also points out these were laboratory based tasks, so it is possible the results reflected much harsher parenting methods in the home.

It is highly unlikely there will be one single factor that emerges as predictive of poor mental health, explains Dr Simmons, but rather there may be a range of tests that work together to identify at risk children. Historical experience of trauma and hormonal profiles are likely to play a key role, along with known at-risk periods.

“While humans have evolved in incredibly diverse environments and we are very resilient as a species, there are particular periods of development where things are more likely to go wrong,” says Dr Simmons. “These sensitive periods include foetal development, early childhood and puberty.”

This latest study means the team can combine information about alterations in hormone levels with existing knowledge, to start to build a more nuanced picture of the factors that lead to mental ill health and, ultimately, help prevent its onset in young people.

Banner image: Am I alone?, Alban Gonzalez, via Flickr