Lunch Hour Lecture: Childhood maltreatment through the lens of neuroscience and epigenetics
By Thomas Hughes, on 26 February 2016
How do childhood experiences affect a child’s propensity to mental health issues later in life? Can childhood trauma be directly linked to higher rates of depression and anxiety? In this Lunch Hour Lecture by Professor Eamon McCrory (UCL Psychology and Language Sciences), he demonstrated how epigenetics and neurocognitive research is helping to understand how brains adapt to adversity.
As society is beginning to recognise the importance of mental health, more effort has been put into finding how the brain processes this abuse or neglect in children so that we can formulate preventative treatment.
Rats and the epigenetics of nurture
Professor McCrory started by talking about epigenetics research with rats. Those brought up in a nurturing environment, where the mother cares for the young, grow up to demonstrate less stress and anxiety. They also grow up to be nurturing parents themselves.
Rats brought up in environments where there is little or no nurturing show much greater levels of anxiety and are quick to panic. This is thought to be a survival mechanism to adapt to dangerous environments. They similarly grow up to be neglectful parents.
Interestingly, though, baby rats born from neglectful parents can be fostered by nurturing parents and they will grow up with minimal stress and anxiety and will become nurturing parents themselves.
This is the idea behind epigenetics, that changes are not hardcoded in the DNA, but rather are something that can be turned on and off by environmental factors.
If it can be turned on, can it be turned off again? Further research is needed to see if therapy can reverse epigenetic DNA changes.
Adapting to threats
Professor McCrory then talked to us about the research into the neurocognitive behaviours of children who had been abused.
We all react to threats in two ways; on a conscious level and on a subconscious level. If the brain sees a spider on your arm it recognises an immediate threat, and without thinking, tries to remove it. As Professor McCrory said, “You don’t sit there thinking, ‘that’s interesting, I wonder what species that is.’”
However, if you see a man begin to pull a gun, you are more likely, unless you have experience of that threat, to think it through consciously, recognise the danger and then act.
Children who have been neglected or abused are much better at detecting threats or anger. When shown flashes of angry or calm faces for less than 13 milliseconds – beyond the ability of the brain to process the images consciously – they are much more likely to notice subconsciously the angry faces as threats than other children.
Soldiers have shown a similar adaptation after returning from conflict – they are much quicker to notice threats. Clearly, the brain is calibrating itself to adversity.
This recalibration is in itself not a problem, but it has been shown that this kind of adaptation to adversity can trigger mental health issues, such as anxiety and depression, when subjected to stress in later life. Soldiers with this recalibration are also more likely to suffer from post-traumatic stress disorder.
This ‘threat detection’ is one method of assessing abused children for the possibility of future mental health disorders, but there are a number of others.
One is to examine the child’s autobiographical memory. This is the body’s way of identifying itself by building a record of our own lives. Children who have been abused tend to supress their past or generally have poor autobiographical memory.
This is important because autobiographical memory functions as a tool for us to build resilience to unknown or stressful situations. “I am less stressed talking in front of you because I have done it before,” Professor McCrory said.
Without the ability to build a catalogue of memories of how to deal with difficult situations, children who have been abused are more susceptible to extremes of stress in later life, triggering depression or anxiety issues.
Professor McCrory says that the next stage is to build therapeutic methods to help treat the underlying issues of abuse before these become mental health problems – but to do this we will need to continue to research how abuse can affect children’s mental health in later life.