We have over 100 hormones and brain chemicals running around our bodies. You know a lot of them…things like testosterone, adrenaline, serotonin, and dopamine. When we live lives that produce a high level of one of these chemicals over a long period of time for whatever reason, that chemical begins to shape and sculpt certain characteristics of the brain.
Nature is neutral about the life we’re going to have. We can go either way—a tough, difficult, stressful, traumatic life or a peaceful, easy life. In either case, nature gives you a brain that can adapt.
For example, one of the major chemicals associated with stress is called cortisol. We are designed to have cortisol elevated for about 20 minutes at a time, and then it decreases and makes its way out of our system. If you are in a high pressure situation where you face continual threat or stress, cortisol stays elevated for long periods of time. We all have experiences like this—some really high profile project at work that stresses us out for three weeks or for a school-aged child a history test. If someone has high levels of stress in early life—from child abuse, domestic violence, living in a war zone, famine—the cortisol can actually kill off baby cells in the brain and then certain regions of the brain are ultimately smaller than they would have been without cortisol.
The stress hormones exert influence on the brain and we end up with a brain that’s wired for the characteristics of “fight or flight”. For example, people who have had traumatic stress from conception to the toddler years will have a higher baseline of cortisol in their bodies. As a result, these folks have a very short fuse. In addition, they have an extremely difficult time calming themselves. Calming is a skill they need to learn.
It’s tempting to say this is maladaptive. But if someone is able to take their biological tendency to be impulsive and they are able to learn the skills of making GOOD decisions in a quick way, we say they are decisive and we say they make good CEOs, doctors, lawyers, etc.
All brain regions do not fully develop at once. Development unfolds region by region – providing us with the essential survival and other capabilities needed at each stage. As each part of the brain develops, there are critical times when the brain region is forming mass. There are also sensitive periods when the brain region is adapting functional qualities with the biological assumption that lifetime experience will generally follow the patterns of childhood experience.
Each brain region has critical and sensitive periods when it is particularly influenced by experience. The first months and years of life are foundational. During pregnancy, infancy and the toddler years, many parts of the brain are sensitive to experience; adaptation during this foundational period forms the cellular platform from which future stages of development emerge. That’s why people say that early childhood is so important – and they’re right.
But, early childhood isn’t the only sensitive developmental period, according to the latest research. Middle childhood – from 7 to age 9 or 10, during puberty, and also around ages 15 and 16 are known periods of sensitive development in the brain. There is good reason to believe that these critical and sensitive developmental periods are also windows of opportunity to build resilience – after all, these are times when the brain is sensitive to experience, bad or good. So, knowing these times can help us do a better job parenting and challenging children in ways that promote life-long health and well-being.
In addition, nature also gives us genetic predispositions. Will you have Uncle Bob’s nose or Grandmother’s hair color? The same is true for ADHD. Our brains develop with those genetic codes imprinted and then environmental factors, like those discussed above, can sculpt that brain to have poor regulation of attention, impulsivity, and hyperactivity. No two brains are alike and no two ADHD children are alike leading us to recognize the importance of fine-tuning treatment decisions for each child.
Brain research continues to inform our knowledge about certain areas and certain chemicals of the brain controlling the symptoms of ADHD-Stay Tuned!
Sheila Woods MD
September 18, 2012
What does recent brain research tell us about the neurobiology of ADHD?
“Neurobiological and Behavioral Consequences of Exposure to Childhood Traumatic Stress,” Stress in Health and Disease, BB Arnetz and R Ekman (eds). 2006. Martin Teicher, Jacqueline Samson, Akemi Tomoda, Majed Ashy, and Susan Anderson