ADHD or Attention Deficit Hyperactivity Disorder is a behavioral syndrome that affects three primary areas of functioning: hyperactivity, impulse control, and attention. ADHD involves the frontal lobe of the brain – the area that affects behaviors in these three domains. It is a syndrome, which means these symptoms tend to happen together with no single specific cause. The brain and ADHD are each complex, so that it is almost impossible to isolate a single cause of ADHD in any individual. However some of most often suspected causes include: mild closed brain injury (falls, concussions, etc.), chemical injury to the brain such as exposure to drugs or environmental toxins during critical stages of brain development, brief lapses of oxygen (anoxia) that injures the brain, and inheritance or DNA vulnerabilities. The injuries that cause ADHD are subtle and rarely observed at the time they occur. The three behavioral symptoms only show up later and so we rarely associate them to the causes. Since some of those causes are unobservable, there is no clear or definitive answer to “What caused this.”
The brain is astoundingly complex, and this is particularly true of the frontal lobe – the area implicated in ADHD. This part of the brain is the “master conductor” that tells the other parts of the brain what to do, when to do them, when not to do them, what to attend to, when to quiet down, and when to remain silent. It is the part of the brain we most closely associate with our will or with that sense of “I” when we initiate actions. ADHD may be due to an injury to the frontal lobe directly, or it may be damage to some of the millions of nerve fibers going in and out of the frontal lobe which communicate with the rest of the brain. Or it may be that the brain chemistry affecting the frontal lobes is not quite right. Whatever the specific cause, most research points to frontal lobe problems as the “place” where ADHD happens.
Because of this frontal lobe complexity, there are many individual differences in the behavior of people diagnosed with ADHD. Some show extreme hyperactivity, and some exhibit none at all. Some have varying degrees of ability to focus. while some cannot sustain attention for more than a second or two. Some can hyper-focus when very interested in something, but cannot break off from this hyper-focus when their attention is needed elsewhere. Some have very poor short-term memory, while others are less forgetful. Some have very poor self-management and organizational skills (what psychologists call executive functioning) and some are less plagued with this problem. And any or all of these symptoms may come and go, influenced by fatigue or poor sleep. Because of this variability, some erroneously conclude, “there’s no such thing” as ADHD. Or they’ll say, “I don’t believe in ADHD” as though it is a matter of faith. But the ADHD syndrome is very real and very disruptive to the lives of those who have it and to their loved ones working to raise or support them.
Check back for the next article on how ADHD is diagnosed, and helpful information on the behaviors and symptoms associated with ADHD.
-Dr. Mark Dobbs