Early life experiences can change brain development, result in health problems, including addiction

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‘We know the stress responses of people who experience adversity in childhood can be sensitized in the long term,’ says neuroscientist Dr. Nicole Sherren

Whether it’s adverse childhood experiences or toxic stress, there are a variety of factors that could potentially result in a person having a substance abuse issue.

Just over 125 people jumped online earlier this week for a Simcoe Muskoka District Health Unit educational event to learn about the root causes contributing to harmful substance use and how experiences in early life  and at other sensitive periods of development  can change our brains in ways that can make us more vulnerable to issues such as addictions. 

Those reasons are many and all lead back to one place  the brain, according to keynote speaker Dr. Nicole Sherren, who explained building resiliency at the individual, family and the community level can help tip the scales in a more positive direction. 

Balancing the scale

“We’ve learned over the last 20 years that resilience is a brain-based concept. We now know that (it’s) not just a trait of certain lucky people, it’s actually a skill and ability that can be built over time. We now think about it more as a positive outcome in the face of negative experiences as well as a dynamic capacity and skill that can be built over time,” she said.

Sherren said it’s helpful to think about resilience as a scale, with positive support and experiences (such as adequate nutrition and sleep, physical activity as well supportive relationships, environments) on one side. That scale would be counterbalanced by the negative experiences a person could experience (such as abusive relationships, living in poverty, not having access to health care). 

The last component of resiliency serves as the tipping point and is the basic biology that we are all born with which starts in a different place for each individual, she added. If you have a tipping point that’s positioned more on the negative side, that means it’s going to preference the weight on the negative side… and vice versa.

“What we want to happen for a positive outcome is we want that scale to tip in the positive direction regardless of whether or not there is negative weight on that opposite arm,” she said. “It turns out the tipping point, our basic biology, is actually sensitive to the experiences that we have in childhood and across our lifespan. 

“That means we can actually shift that tipping point in key ways provided we are giving children  and adults  the right kinds of supports and experiences to influence our biology in key ways and make that positive outcome more likely to happen over time.”

Building strong foundations

Brain development is a long process and it’s important to have a strong foundation.

“Think about the process the brain uses to guide that development as being similar to the process you’d use to build a house. First you need a basic blueprint, which will tell you the relative size, how many rooms there are and where they are,” she explained. “It’s not going to tell you what the house will look like at the end of the day. That’s going to depend on the finishes you put into the house.”

The same thing can be said for brain development.

“The brain also has a basic blueprint that guides the developmental process. What genes do is provide a basic blueprint, but they don’t dictate what that structure is going to look like at the end of the day,” she said. “Same as when you build a house, you’re going to dig a hole and build a strong foundation because that has to support all of the visible structure you’re going to build on top… if you get a crack in your foundation you could potentially end up with a crack in your roof over time. 

“In the same way, during development the brain is busy laying, hopefully, a strong foundation that’s going to support more complex circuits that emerge over time. So, just like where the kinds of finishes you use in that house is going to dictate the quality of that structure, in the same way, the quality of the experiences we have during development also dictate the quality of the structure of that brain that’s going to be built over time.”

Use it or lose it

When it comes to the developing brain, more connections between signals are not necessarily better, said Sherren, noting during the normal developmental process the brain actually removes connections from neuro-circuits to create speed and efficiency in processing information. 

“The reason the pruning is such an important mechanism that guides brain development is because it is experience dependent. It happens in a use it or lose it kind of fashion.”

That means the connections that get used the most are the connections that will get strong and stable. The connections that don’t get used often, she noted, the brain figures are not useful and will ultimately weaken and eventually pruned away over time.

Early socialization can improve development

Although a variety of experiences can impact brain development, Sherren said there is only one experience they know of, if absent during the developmental period, that will result in deficits across multiple functional domains: Social interactions. 

“We often think of them as being a serve and return between a child and a responsive adult. The goal of these styles of interactions is to build key neural circuits in the brain through practice, practice, practice. They are really critical in building basic cognitive, social and emotional skills that will set us up well and provide some of that foundation for resilience as we move forward throughout life.”

All social species, if they have a lack of support during critical developmental periods, can show sensitization of their stress response system, noted Sherren, adding if these genetic changes occur they’re often permanent. 

“We now think this is the key biological basis for intergenerational trauma… and can potentially be perpetuated across the generations through a genetic mechanism.”

Environmentally friendly

The effect of the environment you live in can also play a role in your brain development and ability to build resiliency.

“Imagine a child growing up in a stable two-parent family with access to high-quality child care, a safe playground where they can get lots of physical activity and lots of interaction with their peers, engaged teachers: this environment is helping them exercise a number of pro-social skills and abilities which then sculpt key pro-social circuits in the brain,” Sherren said.

That child, she noted, is likely getting the opportunity to practice strong, trusting, attachment-based relationships with adults around them, as well as multiple opportunities to practice early language and literacy and emotional control.

“This child is likely going to get a pretty strong foundation of basic pro-social skills that will stand them in good stead as they continue to grow and mature.”

A child growing up in a different type of environment, she added, who may be witnessing domestic violence, substance use by their parents, and don’t have access to quality child care is having a very different experience.

“This is essentially driving that pruning process in a very different way. They’re likely practicing a lot of skills and behaviours around anger and aggression because this is what they’re seeing.”

Those early environments, she continued, can either set a child up with a very solid foundation or potentially with a shaky foundation.

Getting set up for success

Some of the most important skills and abilities we need are developed through our executive function, which Sherren said helps us navigate through complex physical, social and emotional environments.

“These skills are critically important for us and turns out when they’re working well they’re pretty much invisible. It’s when they’re not working well we can see difficulties. … They’re incredibly important to us and might predict what we call key outcomes that would define a fairly successful citizen in society.”

Not all stress created equal

Stress also tips the scale in the “negative” direction, said Sherren, noting while not all stress is the same it does shape the developing brain in key ways that either sets us up to cope well or to potentially struggle. 

There are three types of stress, she noted: Positive stress, tolerable stress and toxic stress  the latter of which is what can have a negative impact on the developing brain. 

“A prolonged activation of the stress response systems… in the absence of adequate adult support… get biologically embedded in a key way into the developing brain and take that developing off its best track,” she said. 

Adversity very early in life can also create a profound effect, she added, noting a person doesn’t have to remember what happened to them in order for that event to have an impact on their biology.

“A six-month to one-year-old baby has a stress response system just like a six- or seven-year-old child does or a 70-year-old adult does. When that is active for long enough it’s going to impair some of our skills and abilities,” Sherren said. 

The path to substance abuse can also begin with depression. 

“As the number of adverse childhood experiences increase the risk of developing substance misuse increases as well. There are many pathways that bring people to substance misuse,” she said, adding there are certain genes that can make particular people vulnerable to substance misuse.

“We know that if parents have a substance misuse problem a child can learn this is a good coping strategy and emulate that as they continue to grow,” Sherren added. “We know addiction involves deficits in prefrontal control. We know the stress responses of people who experience adversity in childhood can be sensitized in the long term. These substances decrease stress and boost our mood… so these are potentially short term solutions to problems that were really founded by the presence of toxic stress early in development.” 

Never too late to learn

It’s not all bad news, however, says Sherren.

“Most people who experience adversity in childhood do end up with fairly good outcomes in their lives… it is not a guarantee, but merely a risk factor. The positive experiences and supportive relationships continue to build resilience both in children and adults,” she said. “It turns out it’s never too late to build resilience. Even though it’s easier, faster and cheaper to get it right the first time, it is possible to teach an old dog new tricks.”

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