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Attention deficit/hyperactivity disorder is a well-known affliction that is characterized by difficulties in impulse control, hyperactivity, and a reduced ability to concentrate for extended periods of time. While it is typically considered to be an issue afflicting children and young adults, a growing body of research has revealed that ADHD does not disappear when one reaches adulthood. It is now estimated that symptoms persist into adulthood for as many as 60 percent of those who are diagnosed with the disorder during childhood.
Unfortunately, because it is so commonly believed that ADHD is something that one simply grows out of, many adults do not seek treatment for the disorder.
The Causes of ADHD
Genetic factors play a significant role in ADHD. Writing in Neuropsychiatric Disease and Treatment, a team of researchers found that, “If one person in a family is diagnosed with ADHD there is a 25-35 percent probability that another family member also has ADHD, compared to a 4-6 percent probability for someone in the general population.” They also claim that approximately half of parents who had the disorder have a child with ADHD.
Beyond genetics, some other factors the team cited include childhood exposure to high levels of lead, infant hypoxic ischemic encephalopathy (when newborns do not receive enough oxygen to their brains), and prenatal exposure to nicotine. Children who suffer traumatic brain injuries have also been shown to exhibit symptoms associated with ADHD, though the National Institute of Health notes that this is not a common cause of ADHD.
Finally, and perhaps more controversially, some have suggested that the increased frequency of ADHD diagnoses in more developed countries may be linked to changes in diet, particularly with regards to the increased consumption of refined sugars. While it is advised that children and adults avoid processed foods and refined sugars for optimal health, it is too soon to say that there is a clear causal link between excessive sucrose consumption and ADHD. More studies are needed.
ADHD and Brain Chemistry
Imagine trying to read an in-depth news article while on a crowded subway train filled with conversation, music, the occasional panhandler, and frequent announcements about upcoming stops and other issues deemed important by the train’s conductor. Now imagine trying to read the same article in a quiet study without any of the din found on the train. Obviously, it is far more difficult to focus in the former scenario than in the latter.
Unfortunately for those with ADHD, even relatively quiet settings can end up feeling like that crowded train. They feel inundated by external stimuli, thereby making it difficult to filter out the background noise and to concentrate on singular tasks.
While the neurophysiological causes of ADHD are not fully understood, most researchers believe that there are key differences in the brain chemistry of people who have ADHD and the brains of people who do not. These researchers contend that people with ADHD have imbalances in the levels of the neurotransmitters dopamine and norepinephrine. These neurotransmitters interact to regulate attention.
Dopamine
Dopamine is commonly associated with pleasure and reward, as it activates the so-called reward pathway of the brain. People with ADHD do not efficiently process dopamine, which means they must seek out more activities that activate the reward pathway. According to a 2008 paper published in Neuropsychiatric Disease and Treatment, “People with ADHD have at least one defective gene, the DRD2 gene that makes it difficult for neurons to respond to dopamine, the neurotransmitter that is involved in feelings of pleasure and the regulation of attention.”
Norepinephrine
Patients suffering from ADHD do not efficiently make use of the neurotransmitter and stress hormone norepinephrine. When an individual feels endangered, a flood of norepinephrine is released to increase alertness and to enhance our sense of fight or flight. At more normal levels it is linked to memory and allows us to maintain interest on a given task.
Dopamine and norepinephrine impact four distinct parts of the brain:
- The frontal cortex, which gives us the ability to plan and organize while focusing on and identifying internal and external stimuli;
- The limbic system, which regulates our emotions;
- The basal ganglia, which regulates communication between different parts of the brain;
- The reticular activating system, which can be characterized as the gateway to our consciousness. It is the part of the brain that allows us to determine what to focus on and what to tune out as white noise.
Other Theories
However, not all researchers agree that ADHD is caused by irregularities in the processing of these neurotransmitters. An intriguing study by a team of researchers at the University of Cambridge in the United Kingdom found that ADHD may be caused by “structural differences in the brain’s gray matter.” After providing both healthy volunteers and patients with ADHD medication that is known to increase dopamine levels, they found that the drug improved both groups’ ability to concentrate. This would suggest that there is no underlying problem with the neural pathways responsible for processing dopamine.
Professor Trevor Robbins, one of the study’s co-authors said, “These findings question the previously accepted view that major abnormalities in dopamine function are the main cause of ADHD in adult patients.”
Regardless of which theory proves correct, one should not conceive of ADHD as a weakness or a character flaw. One should treat it as one would treat any other disorder.
What Adult ADHD Looks Like
For those whose ADHD persists into adulthood, the imbalances of norepinephrine and dopamine continue, as well. However, the symptoms of ADHD tend to manifest themselves in adults in a way that is slightly different than how they manifest in children. While children who have ADHD are known to be easily distracted and to have problems following rules at home or at school (which can lead to underachievement and underutilized potential), the symptoms of ADHD in adults are subtler, though they can be just as pernicious.
In most instances, ADHD that persists from childhood and remains present in adulthood is less about hyperactivity and more about restlessness, impulsive behavior, and the inability to plan or manage things like time, finances, and even emotions. These symptoms can make sedentary activities difficult and can also have a negative impact on relationships with coworkers, friends, and loved ones. More extreme symptoms can lead to the fraying of these relationships, financial difficulties, and employment problems. An increase in these stressors can trigger more troubling disorders like anxiety and depression.
For those who have a difficult time concentrating and feel as though it is not simply a passing phase, it is possible that you may still have ADHD (provided you were diagnosed with the disorder while in childhood) or you may have a mild form of the disorder that did not meet the threshold of DSM-V when you were first evaluated. (There is also the distinct possibility that there may be a late-onset disorder that shares the symptoms of ADHD, but it has yet to be given a name.)
Then again, not every person who has difficulty concentrating has ADHD. The good news is that through an evaluation, medical professionals can determine whether or not you have adult ADHD. They can also provide highly effective medications that can help individuals manage these symptoms.
However, it is imperative that one does not self-diagnose. It is even more dangerous for patients to self-medicate with the kinds of drugs that are often prescribed to patients with ADHD. These stimulants improve symptoms in those with valid cognitive problems, but they do pose potential risks for abuse and can produce secondary side effects. Even if misuse has become a common phenomenon, particularly among young adults who are in college or pursuing a post-graduate degree, these medications should not be taken by individuals who have not been prescribed them or taken in dosages higher than what is recommended by a medical professional.
It is vital that one consult a physician for an evaluation to determine the best course of action.
Dr. Ahmad reports no conflict of interest. He is not a speaker, advisor, or consultant and has no financial or commercial relationship with any bio-pharmaceutical entity whose product/device may have been mentioned in this article.
