Biological science can at last predict vulnerability, allowing families and governments to intervene pre-emptively and effectively.
The US epidemic of childhood mental illness recalls the crisis of Philip Roth’s “Nemesis.” Set in 1944 Newark, Roth’s novel portrays polio inexplicably sweeping the city, particularly the poorer neighborhoods. Today’s childhood mental illnesses—such as depression, anxiety, attention deficit hyperactivity disorder (ADHD) and drug addiction — also hit mainly the disadvantaged. As with polio, no one can predict who will fall victim, who will escape or why. No child, rich or poor, is completely safe from mental illnesses whose transmission mechanisms are only partially understood and whose debilitating impacts are often life-long.
Yet all this could change thanks to better understanding of epigenetics – the process by genes are switched on and off. These studies hold the promise of identifying, early on, which children will probably become mentally ill. Families and governments will then have the opportunity to take pre-emptive, targeted and effective action.
By 1955, identification of the polio virus and introduction of a vaccine put an end to repeated epidemics. Likewise, today, biological science is poised to resolve the apparent randomness of childhood mental illness. The big question is: which children are most vulnerable and why? Tests could soon spot children at risk even before a single symptom appears. As a result, many childhood mental illnesses could, like polio, cease to be unpredictable mysteries that inexplicably afflict some children and not others. Mental illness, once anticipated, could be alleviated through early interventions before it takes hold.
“Tests could soon spot susceptibility before a single symptom is manifest – even in babies. Many childhood mental illnesses, like polio, could soon cease to be unpredictable mysteries. Mental ill-health, once anticipated, could then be alleviated dramatically.”
We now know that childhood adversity, associated often but not always with poverty, can turn genes on and off and thus inhibit healthy responses to stress, leaving children vulnerable to mental illnesses that can last a lifetime. The big breakthrough in epigenetics arises from recent discoveries that these biological effects leave chemical markers, which can be measured simply, even in newborns, by using swabs to collect saliva and a few cells from inside the cheek.
The chain of experiences leading to personal mental illness can be long. Our research has isolated biological markers of mental health vulnerability in blood from the adult offspring of Holocaust survivors, sometimes decades after those survivors died. These markers reveal that this particular trauma affected the mental health not only of the initial victims, but also of their children. The markers in the blood of the offspring generation further show that the legacy can be passed even onto grandchildren – perhaps biologically (we can’t prove this yet) but, highly likely, through living with parents who are themselves not mentally well.
The challenge for intervention programs is to assess the impact of adversity at the level of the individual child – epigenetic measures will likely achieve this goal. The implications of finding these markers for individual children are considerable. First, public agencies can take pre-emptive action to support those most prone to depression, anxiety, ADHD and drug addiction. Better targeting is more efficient and effective, focusing resources on children at risk.
Second, biological information can empower poorer families and communities where stress and childhood adversity, associated with being poor, can seriously compromise brain development. Poverty typically undermines the mental health of parents, imperiling the quality of parental care and thus children’s own mental health. But some children are unaffected. Knowing precisely which ones are at risk can encourage parents to act. Cohesive families, even among the very poorest, can help children to be more resilient, buffering them from mental health risks. Difficult family circumstances need not dictate a child’s destiny. Parents living in even the most impoverished conditions can effectively protect their children. Indeed, the same biological tests that highlight vulnerability could also confirm when good parenting is working and is reducing a child’s mental frailty.
The biological sciences are challenging policy makers and practitioners to spot the vulnerable early and to act swiftly and effectively. Worldwide, the leading health burden is mental illness, not diabetes or heart disease. Many US families – rich and poor — recognize this reality all too readily. And whereas heart disease generally shows some mercy by arriving later in life, mental disorders most commonly appear in later childhood or adolescence, derailing individuals in their prime.
Our next step must be to develop not only effective “markers” of high risk for individual children but to put them into use in community settings or pediatric clinics at pre-school ages. That’s when interventions are most effective. Think of all the polio cases – and the accompanying lifelong tragedies – that have been prevented. We can do this for childhood mental illness.
Yehuda, R. et al. (2014), Influences of maternal and paternal PTSD on epigenetic regulation of the glucocorticoid receptor gene in holocaust survivor offspring, American Journal of Psychiatry 171.8
Zhang T-Y & Meaney MJ (2010), Epigenetics and the environmental regulation of the genome and its function, Annual Review of Psychology 61