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04 October 2019

Linking neurons and neighbourhoods: It’s time to rethink our early childhood development interventions

The backdrop of two hypothetical children’s lives in the same block of flats in Hillbrow is intractable poverty, crime and inequality – but the way they eventually turn out couldn't be more different.

Imagine two children spending the first few years of their lives in the same block of flats in Hillbrow, Johannesburg.

Their families/parents moved to the fairly small, yet crowded inner city neighbourhood to find work in the wealthier suburbs close by. The backdrop of our two hypothetical children’s lives is intractable poverty, crime and inequality, breeding high incidence of stress and mental illness.

Serious crimes such as murder, assault, rape, and robbery are common in Hillbrow – the combined rate for those acts is the fourth highest in South Africa. In 2018, 4 334 such crimes were reported at the local police station.

Dramatic difference

That’s about 11 serious crimes a day in an area that’s only just over a square kilometre. Our two hypothetical children are experiencing violence everywhere: in their homes, on the streets, and at school.

However, by the time they are 25 years old their life stories have played out dramatically differently. One of did not complete his secondary education, has had run-ins with the law, and has not seen the child he fathered at 19 in two years.

The other finished school with an above average grade, has never seen the inside of a jail cell, and is in his third year at university. While survival is difficult – money is always short – he has, against all odds, managed to navigate his way through life, drawing on a deeper well of courage and resourcefulness. 

Not simply nature and nurture

In his latest book, The Orchid and the Dandelion, veteran paediatric researcher of the University of California, San Francisco, Professor Thomas Boyce, describes how children may grow up to be entirely different human beings despite hailing from similar environments and even the same family.

His theory is that some children are orchids, needing special attention to thrive, and others are dandelions, able to adapt and prosper in almost any environment. The reasons for this are not entirely understood, says Boyce. This question – why some succeed and why some struggle – has plagued scientists in the field of child development since the beginning.

The age-old nature versus nurture debate has tried to pin down the reasons why some people are resilient and thrive despite adversity while others don’t. Almost a decade ago, Professor Arnold Sameroff wrote: “Practically, the nature-nurture question comes into play when a child has a problem and the question arises, "Who is responsible?"

Most parents’ first response is to blame the child, and most professionals’ first response is to blame the parents. However, most scientists know that it is both. It is both child and parent, but it is also neurons and neighbourhoods, synapses and schools, proteins and peers, and genes and governments. Professor Shane Norris, director of Centre of Excellence in Human Development hosted at Wits University, adds: “There’s no longer a simple nature and nurture dichotomy when discussing what influences health.

'A unified biopsychosocial response'

"Instead we see how biological and environmental systems and processes mutually influence the other. Like the yin and yang symbol, biology and the environment are intrinsically connected, and cannot exist in isolation."

The way environments and human biology relate to one another opens the early childhood development field to consider what Sameroff coined “a unified biopsychosocial response”. This is suggesting that “multidirectional” models be applied to understanding development.

These are gene-environment interactions that effect the shaping of one’s brain. The notion of brain plasticity – that the brain is constantly able to form new pathways – is evidence of this dynamic relationship. "At the most fundamental level of the universe there are no ultimate units, only ultimate relationships."

"In the dialectical yin-yang there is a unity of opposites and an interpenetration of opposites,” says Sameroff. In South Africa, conversations on improving health and wellbeing are heavily biased towards fixing environmental factors that lead to poor health: poverty, inequality, unemployment and low levels of quality educational attainment."

Professor Mark Tomlinson from the Institute for Life Course Health Research at Stellenbosch University suggests that a more useful approach to improving lives would be to avoid once off, unidimensional intervention programmes, and  instead adopt a “biopsychosocial mindset”.

A South African biopsychosocial discovery

Between 1999 and 2003, Professor Tomlinson together with colleagues from the universities of Cape Town and Reading (in the UK) ran a study where pregnant women received a home-based parenting intervention to improve attachment with their children.

A caregiver is encouraged to be responsive to their infant’s cues. This means cooing back if the infant makes noises, and cuddling the infant. Crying is often a form of communication, and caregivers are helped to understand and cope with these stressors.

 “Attachment” is a well-recognised measure of a child’s psychological security – a critical factor for future wellbeing. (British psychiatrist John Bowlby first coined the notion of attachment in the 1960s, which informs a child’s ability to form a strong, loving, and responsive relationship with at least one caregiver. Psychiatrist Bessel van der Kolk in his 2015 book said that children who don’t feel safe and loved in infancy have trouble regulating their moods and emotional responses as they grow older.)

When the babies in Tomlinson’s study were 18 months old, their attachment to their mothers was measured. It was found that the intervention in 2017 produced a small-to-moderate increase in mother-child attachment. Since home-visiting programmes were seen as the gold standard of early childhood intervention, important questions needed to be raised about effective psychosocial interventions in the early years. 

Tomlinson’s curiosity was piqued. It seemed that more was at play. “I became a researcher for this precise reason. I didn’t want to confirm what we already know, but to push myself to discover what we don’t know. A lot of our studies that tested behaviour change only touched vaguely on the reality.

'The team were stunned'

"In fact, there is so much more at play. If we want to understand the pathways and the mechanisms of change in early childhood development across the life course, we need to probe more because we know next to nothing,” said Tomlinson. Nine years after the original results, Tomlinson and his colleagues conducted a follow up study.

The team knew from other studies that children respond differently to psychosocial interventions, and for some of these children, there are genetic reasons. So in the follow up, genetic specimens were collected and results re-examined.

The team were stunned. “The intervention had in fact worked well for toddlers who had a particular genetic characteristic but had much less of an effect for others,” says Tomlinson. 

The researchers factored in whether the child had the short or long form of gene SLC6A4 which produces a protein that transports the brain chemic serotonin. That molecule is involved in nerve signalling, and studies have linked it to anxiety and depression.

Serotonin is popularly thought to contribute to feelings of well-being and happiness. Previous studies have also shown that individuals with the short form of SLC6A4 are generally more sensitive or "susceptible" to psychosocial interventions; in other words, they benefit when they get it, and do not benefit or actively suffer harm when they do not get it. 

The children with the short form of the gene, and whose pregnant mothers received the intervention, were almost four times more likely to be securely attached to their mothers at 18 months old (84%) than children carrying the short form whose mothers did not receive home visits (58%). 

Higher quality of life

Meanwhile, children with the long form of the gene were apparently unaffected by their mother’s training or lack thereof: in both cases, the children’s rates of secure attachment were almost identical (70 and 71%). 

According to Tomlinson’s co-author of the 2017 follow-up study, Dr Barak Morgan, this “may mean that this group of children appear less susceptible and derived little benefit from the same intervention, and little detriment from not getting it”. The findings provided the tantalising possibility of being better able to focus early years intervention efforts to ensure that everybody receives appropriate help. 

Mercy Manyema, doctoral researcher in adverse childhood experiences and its effects on health, confirms that children with the short form of the serotonin transporter gene are more vulnerable to the effects of poor home and community environments and that social support interventions are critical for these kinds of children. However, "dandelion" children or those that show greater resilience despite life’s adversities, should certainly also receive early intervention.

In the documentary Brain Matters, it is highlighted how young children – both sensitive and “robust” especially those between zero and three, are primed for learning. Their brains can create over one million neural connections every second. “New experiences lead to new connections… The quality and frequency of new experiences during these early years are vital in building a powerful brain. These magical years of intervention can create changes to last a lifetime,” said director Carlota Nelson. 

Brain Matters explores the four critical “brain-boosting experiences”: nurturing, responsive caregiving; language; play; and nutrition. Investments in early childhood development programmes are linked to higher tax revenues, better educational outcomes, reduced crime and a higher quality of life. 

Image credit: iStock

 
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