As Dr. Perri Klass points out in her piece in the December 13 New York Times, scientists and physicians now widely recognize Attention Deficit Hyperactivity Disorder (ADHD) as a real brain disease. There is still a great deal of debate about the mechanisms in the brain that cause ADHD, but it's clear that the neurotransmitters, dopamine and noradrenaline are somehow involved. It is these two chemicals that are affected by stimulants like Ritalin that are effective in treating ADHD, and a great deal of research shows that these drugs have positive effects on the ability of children with ADHD to control and focus their behavior. Further, as Dr. Klass points out, there is strong evidence that ADHD has a substantial genetic component.
However, Dr. Klass gets it wrong when she argues against the idea that the modern device culture may be causing "cultural ADHD":
I've lately read a number of articles and essays that use attention (or its lack) as a marker and a metaphor for something larger in society -- for the multitasking, the electronic distractions, the sense that the nature of concentration may be changing, that people feel nibbled at, overscheduled, distracted, irritable. But ADHD is not a metaphor. It is not the restlessness and rambunctiousness that happen when grade schoolers are deprived of recess, or the distraction of socially minded teenagers in the Smartphone era. Nor is it the reason your colleagues check their email in meetings and even (spare me!) conversations.
This claim highlights a common confusion about biological disorders: Just because a disorder is biologically-based or genetically-influenced does not mean that other factors (such as behavior or the environment) cannot also cause the same problem. Take high cholesterol as an example. There are some people with a genetic disorder called familial hypercholesterolemia that causes their cholesterol levels to be very high, even if their dietary cholesterol intake is low. However, someone without this genetic disorder can also have high cholesterol simply by eating too much animal fat. The fact that high cholesterol can be caused either by genetics or behavior doesn't make it any less of a biological disorder, though it does affect how we go about treating it.
What about "cultural ADHD?" It's clear (at least to me) that the inability to focus that is being driven by the speed and richness of our informational environment bears at least some resemblance to the inattention that marks ADHD. For example, some of the diagnostic markers for ADHD in the DSM-IV (which is the guide that psychiatrists use to diagnose the disorder) include "often has trouble keeping attention on tasks," "often avoids, dislikes, or doesn't want to do things that take a lot of mental effort for a long period," and "is often easily distracted." Sound familiar?
In addition, there are reasons to believe that information overload also affects the same neurotransmitter systems that are dysfunctional in children with ADHD. Dopamine and noradrenaline are important for the prefrontal cortex to function properly, and it is this brain system that allows us to keep our behavior under control. Interestingly, there seems to be a "Goldilocks zone" for dopamine and noradrenaline; either too little or too much and our prefrontal cortex function goes south, leaving us disorganized, forgetful and unable to focus. It is thought that ADHD is related to too little of these transmitters in the prefrontal cortex, whereas too much of them can result from stress. This is why stress can leave us feeling frazzled, and why jitters during a public speech can cause one's mind to sometimes go completely blank. Research has not yet identified whether information overload affects dopamine and noradrenaline in the same way that stress does, but I think we will find that it does, given how similar the outcomes can be.
This argument in no way diminishes the importance of understanding and treating ADHD as a biological disorder. By realizing that there are many ways that humans can become inattentive and distractable, we can start to gain a better understanding of how we might change our behavior, our environment and our brains in order to optimize our ability to focus.