The Science of ADHD

Real Science Defines ADHD as Real Disorder

Some of the most prestigious scientific-based organizations in the world conclude that ADHD is a real disorder with potentially devastating consequences when not properly identified, diagnosed and treated.

Causes and Brain Chemistry

Research has demonstrated that ADHD has a very strong neurobiological basis.

Although precise causes have not yet been identified, there is little question that heredity makes the largest contribution to the expression of the disorder in the population.

In instances where heredity does not seem to be a factor, difficulties during pregnancy, prenatal exposure to alcohol and tobacco, premature delivery, significantly low birth weight, excessively high body lead levels, and postnatal injury to the prefrontal regions of the brain have all been found to contribute to the risk for ADHD to varying degrees.

Research does not support the popularly held views that ADHD arises from excessive sugar intake, excessive television viewing, poor child management by parents, or social and environmental factors such as poverty or family chaos. Of course, many things, including these, might aggravate symptoms, especially in certain individuals.  But the evidence for such individual aggravating circumstances is not strong enough to conclude that they are primary causes of ADHD.  A related problem that has some accumulating evidence is sensitivity to food or additives such as colorings and preservatives.  Several controlled double-blind studies suggest that these might be important for a minority of children with ADHD, and a couple of controlled studies suggest a small effect on all children whether or not they have ADHD.  Further research on this connection is warranted.

Neurochemistry

Structural and functional imaging research on the neurochemistry of ADHD implicates the catecholamine-rich frontal-subcortical systems in the pathophysiology of ADHD. The effectiveness of stimulant medication, along with animal models of hyperactivity, also point to catecholamine disruption as at least one source of ADHD brain dysfunction.

A 10-year study by National Institute of Mental Health found that brains of children and adolescents with ADHD are 3-4% smaller than those of children who don't have the disorder and that medication treatment is not the cause (Brain Imaging in Children with ADHD).

Basic neuroimaging research is being conducted to further delineate the pathophysiology of ADHD, determine diagnostic utility of neuroimaging, and elucidate the physiological effects of treatment.  However, the research is not definitive enough for practical application of neuroimaging.

Executive Function

Many of the symptoms classified as ADHD symptoms of inattention are actually symptoms of executive function impairments. Executive function refers to a wide range of central control processes in the brain that activate, integrate, and manage other brain functions.

Best put, Thomas E. Brown, Ph.D., of Yale University compares executive function to the conductor of an orchestra.  The conductor organizes, activates, focuses, integrates, and directs the musicians as they play, enabling the orchestra to produce complex music. Similarly, the brain's executive functions organize, activate, focus, integrate and direct, allowing the brain to perform both routine and creative work. 

The components of executive functioning that impact school or work:

working memory and recall (holding facts in mind while manipulating information; accessing facts stored in long-term memory)

activation, arousal and effort (getting started; paying attention; completing work)

emotion control (tolerating frustration; thinking before acting or speaking)

internalizing language (using self-talk to control one's behavior and direct future actions)

complex problem solving (taking an issue apart, analyzing the pieces, reconstituting and organizing them into new ideas)

Below is research on the science of ADHD as a real disorder.

American Medical Association (AMA)

ADHD "is a commonly seen neuropsychiatric syndrome that has been extensively studied over the past four decades . . . It should be noted that debate over ADHD within the research and medical communities has been mild and mostly concerned with nuances in the diagnosis and treatment paradigms. By contrast, highly inflammatory public relations campaigns and pitched legal battles have been waged (particularly by groups such as the Church of Scientology) that seek to label the whole idea of ADHD as an illness a "myth" . . . It is thus most important to separate legitimate concerns raised by scientific papers from abstract, distorted, or mendacious information from other sources."