Subjects: Behavioral health
Many people struggle to stay focused nowadays, amid a deluge of cluttered inboxes, electronic distractions, city noise and overloaded schedules. There’s no doubt this challenge is real and quite prevalent, but when some of us claim the challenge is caused by attention deficit hyperactivity disorder (ADHD), that’s a bit much.
ADHD is not a metaphor for modern life, but—as Perri Klass pointed out in an excellent essay for the New York Times—a bona fide, if perhaps over-diagnosed, disorder with specific and increasingly well understood neurological and genetic underpinnings.
As is the case with most medical conditions, ADHD is associated with a broad spectrum of symptoms and disease severity. Typical manifestations in boys are hyperactivity and impulsiveness, whereas girls with the condition tend to be inattentive. Gender differences may explain why girls are diagnosed with ADHD less frequently than boys; it’s possible to be inattentive and unable to focus at school and yet still be well behaved. That’s not usually the case with boys.
Imaging studies of kids with ADHD consistently reveal lower-than-normal activity in the frontal lobes of the brain, areas that help govern sensory input and decide things to focus on. On the neurochemical side of things, it looks like defects in dopamine-mediated circuits that transmit information toward and away from the frontal lobes are involved.
Diminished transmission of neuronal impulses across these pathways probably explains why stimulants like Ritalin and Adderall work in kids that appear to be overstimulated to begin with.
And in a fatal blow to the myth that ADHD is precipitated by an overly multi-tasked society, scientists have shown that the condition has strong genetic underpinnings. In fact, if one identical twin has ADHD, the risk that his twin will have it as well is nearly 80%. Among fraternal twins (that is, twins who do not have the same genotype) the risk is 20-30%, which is equal to that for any siblings.
Further pursuing the genetic etiology of ADHD, Maximilian Muenke and colleagues at the National Human Genome Research Institute showed that a particular gene, LPHN3, was linked to the condition and predicted a positive response to treatment with stimulants.
“In the long run we will be able to develop personalized medicine for a child with ADHD,” Muenke told the Times. “This child will have a very specific treatment, whether this treatment is behavioral treatment alone or medication,” he added, specifying that the medication will eventually be selected based on specific characteristics of each patient.