ADHD and Brain Chemistry (by Steven Novella)

[Heinz-Rüdiger]

http://www.theness.com/neurologicablog/?p=876

ADHD (attention deficit and hyperactivity disorder) is somewhat of a beleaguered and misunderstood disorder. The key controversy (and it is mainly a public, not a scientific, controversy) is whether ADHD is an actual brain disorder, a product of environmental factors (bad parenting, too much TV), or a cultural fiction. As is often sadly the case, I find the public debate largely disconnected from the scientific research[...]

http://www.theness.com/neurologicablog/?p=876

see also (german):
http://www.psiram.com/index.php?title=Ritalinkritik

[Heinz-Rüdiger]

http://www.eurekalert.org/pub_releases/2009-09/dnl-dib090309.php

[...]UPTON, NY — A brain-imaging study conducted at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory provides the first definitive evidence that patients suffering from attention deficit hyperactivity disorder (ADHD) have lower-than-normal levels of certain proteins essential for experiencing reward and motivation.

[...]

The results clearly showed that, relative to the healthy control subjects, the ADHD patients had lower levels of dopamine receptors and transporters in the accumbens and midbrain — two key regions of the brain directly involved in processing motivation and reward. In addition, the measurements of dopamine markers correlated with measures of behavior and clinical observations of ADHD symptoms, such as reduced levels of attention as measured by standard psychological tests.

"Our findings imply that these deficits in the dopamine reward pathway play a role in the symptoms of inattention in ADHD and could underlie these patients' abnormal responses to reward," Volkow said.

"This pathway plays a key role in reinforcement, motivation, and in learning how to associate various stimuli with rewards," she continued. "Its involvement in ADHD supports the use of interventions to enhance the appeal and relevance of school and work tasks to improve performance.

"Our results also support the continued use of stimulant medications — the most common pharmacological treatment for ADHD — which have been shown to increase attention to cognitive tasks by elevating brain dopamine," she said.[...]

Idiots from Holunder, read carefully!