A Focused Mind
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Dr. Kacir's ADHD Blog
Dr. Kacir's ADHD Blog
|Posted on March 5, 2012 at 2:15 PM||comments (38)|
One of my patients asked the question in the title of this post. He also asked if the genetic cause was a mutation. After I answered him, I thought that my readers might be interested in my reply, so I have cut and pasted it below.
ADHD is clearly inherited genetically since it is passed down from one generation to the next as reliably as height is. It is a general rule that boys grow to be about 4 inches taller than the average of their parents' heights and girls to be 4 inches shorter. In the case of height, there are known exceptions, some because of genetic issues (like dwarfism) and others because of developmental or environmental events like accidents or malnutrition.
Several genes have been associated with ADHD. They are not mutations any more than brown eyes are mutations of green eyes. The one gene that I remember is called DR4. It is one of at least 6 different sequences that code for a Dopamine Receptor. More people with ADHD have this particular gene than do people without ADHD. However, not everyone who has this gene also has ADHD and not everyone with ADHD has this gene.
This is probably where the developmental part comes in. It has been shown that young children have more symptoms of ADHD immediately after watching Spongebob Squarepants than they do after watching Sesame Street. It is possible that young children who are exposed to a lot of electronic media might be more likely to have enough symptoms to be diagnosed with ADHD than children who spend a lot of time reading or playing with blocks.
There is also the fact that while only 4.4% of adults can be diagnosed with ADHD, about 50% of the population in prison can be so diagnosed. This means more people who made the choice to do illegal activities (and got caught) exhibit ADHD than those who chose to obey the law. Most of these choices are made during adolescence and can be considered "late developments." It is clear that ADHD is associated with conduct disorder (a developmental issue that leads to problems with law enforcement) but conduct disorder can also occur without ADHD, so there may be reciprocal effects. This would be another example of development affecting the expression of a genetic tendency to ADHD.
To summarize, genes are responsible for the possibility of having ADHD symptoms. Environment and development probably determine whether an individual will have enough of those symptoms to match the full requirements of the diagnosis. There are
many genes involved and it is likely that certain variations of these genes are more common in ADHD. Therefore if more of these genes are the ADHD type in a given person, then that person will have more symptoms of ADHD.
|Posted on September 6, 2011 at 5:51 PM||comments (104)|
I finally finished the book I've been working on for so long and I'm pleased to say that I have gotten a lot out of it. I'm not sure it's what Dr. Barkley intended me to get, however! As I have mentioned, he is a psychologist rather than an M.D., so he doesn't prescribe medication. He very firmly believes in it, but his views on the nature of ADHD are colored by his expertise in behavior management and the descriptive nature of mental disorders up to the last few years. He recommends psychological counseling in addition to medication in every person with ADHD. Furthermore, he is in a large academic center, so he aims to make recommendations that can be supported by peer reviewed research.
As I understand them, these are his new theories about ADHD:
1. It is a disorder of behavioral inhibition, not primarily a problem of attention.
2: The disorder is a delay in the usual pattern of learning to control one's behavior.
3. The usual pattern is an internalization of the external cues/environmental feedback that initially govern children's behavior.
4. Primarily inattentive ADHD may be an entirely different disorder.
I disagree with #1, primarily because I disagree with #4, but I think that his emphasis on inhibition rather than attention is not entirely wrong. As I may have said before, I feel that the basic problem in ADHD is a failure to stop an automatic response to a distraction in order to stay attentive to what one is doing. If that response is an action, then it is a failure of behavioral inhibition. However, if that response is only a change in one's focus it is a failure of attention.
If one adds "and attention" to #2 and #3, I actually agree with them. I don't agree with Dr. Barkley's following suggestion that different behavioral analysis be performed for different age groups. I think that the current symptoms can be adapted by the diagnostician to each patient's developmental stage. #3 gives a very practical suggestion to treat ADHD, which Dr Barkley acknowledges, but does not emphasize as much as his opinions about changing diagnostic and research strategies. Essentially, the person with ADHD can "re-externalize" behavioral/attentional controls. Specifically, one can replace the internal time sense lacking in so many people with ADHD by utilizing timers and cell phone alarms. Written lists replace faulty working memories and rewarding oneself for each completed task with a tangible consequence can enhance self-motivation.
The end result of reading Dr. Barkley's book, ADHD and the Nature of Self Control was that it solidified some of my impressions about the nature of ADHD. It also gave me a lot of food for thought and some practical information for my patients.
|Posted on April 12, 2011 at 5:56 PM||comments (82)|
I just read an article which reviewed functional MRI (fMRI) results in autistic individuals fMRI illustrates brain activity while subjects perform a task. The "investigators found that those with autism exhibited more activity in the temporal and occipital regions and less in the frontal cortex than those without autism." Temporal and occipital regions are involved in perception, while the frontal cortex is in charge of executive function and prioritizing attention to different stimuli. The studies were performed while the subjects performed tasks including face processing, object processing and reading. "This research helps explain autistics' exceptional visual abilities, where at least 1 out of 2 excel in visuospatial tasks," said principal investigator Laurent Mottron, MD, PhD. Later, he suggests "instead of describing autism as a social deficit, "which may be true but isn't very specific," it could be described as "a condition characterized by a brain reorganization in favor of perceptual superiority." When asked about the inference that more activity indicated "superiority" Dr. Mottron said: "Sometimes that corresponds to superior performance but that may not always be true,"
Indeed, in functional imaging of subjects with ADHD, they perform poorly on tests of executive function and exhibit more activity in their prefrontal cortex than do subjects without ADHD. When they are treated with stimulants, they perform better and the amount of activity decreases to match that of someone without ADHD. It seems that this activity corresponds to an increased number of electrical signals being sent without triggering the next action. In other words, the increased activity may illustrate an ineffective "loop" where signals are sent and resent within one part of the brain and don't make it to the part which most efficiently performs the task in question.
|Posted on March 18, 2011 at 5:04 PM||comments (77)|
I just read the summary of an article supporting the theory that ADHD is an extreme of the hyperactive behavior seen in "normal" children. The support was based on
images of the brains of ADHD patients compared to non-ADHD children without hyperactive behavior and then to non-ADHD children with some hyperactive behavior. The authors stated that since the findings in the last group of children were in between those of the other two, ADHD was actually just one end of a "dimensional" spectrum. I was not impressed with the summary of their study, but I do think that their premise is useful to consider. (One of my major objections to the study was their focus only on hyperactive behavior. What about inattention?)
Many parents have questioned the validity of using ADHD symptoms to "qualify" for the diagnosis of ADHD by saying "everybody does that sometimes!" Some have even asked if it is possible to have "just a little bit of ADHD." Agreeing with these two statements would imply that ADHD is merely an excess of "normal" behaviors.
In most cases of ADHD the difference between "normal" and "ADHD" is very clear: there are definitely more than 6 symptoms of either inattention or hyperactivity/impulsivity. However, what should be done for someone who has only 5 symptoms and yet is not doing as well as he or she would like in school and has to work twice as long as siblings do to accomplish chores? Purists would claim that such a person does not have a "disorder" because he or she did not fulfill the definition by which the diagnosis is made. Given that determination, a physician would not be able to prescribe medication since the patient did not have a disease. Indeed, some would say that allowing such a patient to take stimulants would be equivalent to prescribing "performance enhancing drugs" to an athlete.
I am not such a purist. I think that it is possible to have "just a little bit of ADHD." If a person has some symptoms and is experiencing problems in two areas of life, I think that a trial of ADHD medicine is useful. Of course, a medicine should not be used if it causes side effects nor should it be used just for testing or for big projects. (The latter use is typical of how stimulants are abused by college students for whom it is not prescribed.) As with any medical intervention, the benefits must outweigh the risks both to the patient and to society.