ADHD, Substance Abuse, and Impulsivity

A  recent study from the journal Nature Neuroscience suggests that teens who struggle with substance abuse and those with ADHD have somewhat different cerebral profiles, specifically in terms of impulsivity, a feature of both conditions. Both groups exhibit impulsivity, but that trait appears to derive from different areas of the brain. Among the teens who had tried alcohol, cigarettes or other drugs, like marijuana, brain scans showed different patterns of brain activity in the right inferior frontal gyrus and in the orbital frontal cortex compared to teens who had not touched these substances before. These differences showed up in self-control tests during which activity in their brains was monitored. Prior research has found that the right inferior frontal gyrus is involved in the ability to control, or inhibit, impulses. People with head injuries that damage that area of the brain have problems with inhibition. The orbital frontal cortex has been known for years to be involved in drug use.

What’s interesting is that the ADHD teens who were administered this self-control test also showed difficulties with controlling impulses, but their patterns of brain activation were quite distinct. The teens with ADHD exhibited differences in the bilateral frontal lobe and the basal ganglia, both of which are known to play a significant role in ADHD symptomology. So the same end behavior, impulsivity, appears to be linked to different parts of the brain.

The reason this study is important is that ADHD people have a significantly increased risk for substance abuse. The data from this research effort strongly suggest that atypical functioning of certain cerebral networks, those involved in impulse control, underlies addiction.  But impulsivity in addiction, as opposed to ADHD, appears to be a different animal. The study did not examine ADHD people who also were substance abusers. What will be interesting to see is if ADHD people with substance issues look more cerebrally similar to the ADHD group or to the substance abuse group.

Overall, this study shows us that the brain is an incredibly complex organ that we are just beginning to understand. Also, we see that impulse control does not always indicate the presence of ADHD. While it is easy to judge others who show what appears to be a lack of “willpower,” this study points to the underlying biology that is involved, and thus invites us to consider addiction as a bona fide disease.

With ADHD and addiction, many people who are not afflicted presume that a lack of willpower is to blame. “I know when to stop,” they will righteously declare. “They just need to learn their limits.” This scientific information gives us reason to pause and reflect, and perhaps reevaluate how we view both ADHD and addiction, and to consider having more compassion for people who deal with these challenging conditions. So many people presume expertise when dealing with mental health conditions. If you really want to understand mental health, go to school on the brain. I recommend the following books to help you in that endeavor:
1.  Howard, P. (2007). The Owner’s Manual for the Brain. Austin, TX: Bard Press.
2.  Nigg, J. (2006). What Causes ADHD?: Understanding What Goes Wrong and Why. New York: Guilford Press.
3.  Stoehr, James D. 2006. The Neurobiology of Addiction. 1st ed. Philadelphia: Chelsea House.