Have you ever done something without thinking of the consequences that come along with that action? Many individuals who have attention deficit hyperactivity disorder (ADHD) are often impulsive, meaning that they do and say things without thinking. ADHD is the most common diagnosed disorder in children, affecting 3-7% worldwide. It is characterized by symptoms of inattention (i.e., unfocused) and hyperactivity-impulsivity (i.e., restlessness). We tend to think of screaming, chaotic and uncontrollable school aged children when we hear ADHD.
Many researchers are finding that there are physical brain differences in ADHD people compared to those who don’t have ADHD. This is important because children who show signs of ADHD are often over looked in the classroom and their symptoms are viewed as a reflection of poor parenting or a poor diet (i.e., too much sugar). If people knew that there are physical brain differences in those who have ADHD compared to those who don’t, society can begin to understand that ADHD people really “can’t help it” when they are impulsive which can potentially eliminate the negative vibe that surrounds the disorder.
Tajima-Pozo and his team of researchers (2018) suggested that people with ADHD would have a smaller amygdala size than non-ADHD people. What is an amygdala you may ask, it is an almond shape area of the brain that is important for processing emotions and controlling behaviour; it has two sides—a left and a right. A smaller amygdala alters the brain function in those areas, resulting in impulsivity and emotional instability (not being in control of your own emotions). The researchers had 9 ADHD people (who did not take any medication 2 weeks prior to the study to remove any influence it may have) and 9 non-ADHD people participate in their study. The participants were placed in an machine that measured their brain activity, by detecting blood flow in specific regions of the brain, while they viewed neutral, pleasant and unpleasant images. The pleasant and unpleasant images should provoke emotions, thereby activating the amygdala. After the scan, a specialist analysed the participants brain to determine the size of the amygdala. The participants also completed a survey measuring their impulsivity (acting with little or no before thought, reflection or consideration of consequences).
The results show that the ADHD group had a much smaller left amygdala but its more active than the amygdala in heathy group. The cells in the smaller, ADHD amygdala are likely sending more signals to make up for their smaller size, making it more active than the “normal” amygdala. Perhaps it’s the overactive amygdala that leads to ADHD people having difficulty controlling their impulses, behaviours, and emotions.
The authors are also suggesting a controversial theory where the right side of the amygdala is the main area of the brain for controlling behaviour and impulsivity. Even though the study found no difference in right amygdala size between ADHD and healthy participants, they did find a negative correlation between right amygdala size and impulsivity; meaning, people with smaller right amygdala are more impulsive. In short, a smaller right amygdala could indicate symptoms of impulsivity but not necessarily ADHD.
To sum up, the physical brain differences between ADHD and non-ADHD people could be a reason why kids are being disruptive and impulsive, they really can’t help it. Knowing these brain differences could help diagnose ADHD early in children’s lives so they can learn tools and strategies to deal with their ADHD early on. Although this may be a simplistic view on ADHD because some symptoms (like impulsivity) can just be a personality trait, it is important for people to recognize the trend within this research—there are physical brain differences between ADHD and “healthy” people. More research is needed in this area to make the specific conclusion, but this start can help reduce the stigma that hovers the ADHD diagnosis.
Tajima-Pozo, K., Yus, M., Ruiz-Manrique, G.R., Lewczuk, A., Arrazola, J. & Montanes-Rada, F. (2018). Amygdala Abnormalities in Adults with ADHD. Journal of Attention Disorders, 22(7). 671-678.
