Dr. Adams
08-09-2007, 02:49 PM
"In a study which compared healthy controls, adults with attention-deficit/hyperactivity disorder (ADHD), the latter had less dopamine released in the caudate — a brain region involved with attention and cognition — in response to intravenous methylphenidate (Ritalin, Novartis), a stimulant that increases extracellular dopamine levels in the brain.
This blunted response to methylphenidate was linked with symptoms of inattention and higher reports of liking the drug, which suggests that in ADHD, dopamine dysfunction is related to inattention and to a greater risk for drug abuse.
These findings document that the dopamine system, which is very important for modulating attention and motivation, is not working properly in individuals with ADHD. Although ADHD is the most prevalent psychiatric disorder of childhood and has been studied for decades, the specific neurobiological mechanisms underlying this disorder remain unclear. Although research findings point to a disruption in the brain dopamine system in ADHD, for many years there has been a debate about whether dopamine is increased, decreased, or not changed in ADHD.
Compared with the controls, the subjects with ADHD had a significantly smaller decrease in binding of 11C-raclopride in the left and right caudate after methylphenidate, indicating that less dopamine was released in response to methylphenidate in these subjects. This blunted dopamine response to methylphenidate in the caudate in the subjects with ADHD was linked with symptoms of inattention and with higher reports of liking the drug.
Also found was preliminary evidence of reduced 11C-raclopride binding in the hippocampus and the amygdala, which are part of the brain's limbic system that is involved in emotional responses and in memories.
Ritalin or the amphetamine Adderall — are effective treatments for ADHD: they amplify the weak dopamine signals in the brain of individuals with ADHD.
In addition, the findings help elucidate why, compared with members of the general public, individuals with ADHD have a much higher risk of abusing drugs. Drugs of abuse temporarily increase the concentration of dopamine in the brain. People with ADHD are at greater risk of taking drugs, not just because they want to get 'high,' but in their case, it may actually make them feel better. They may end up taking drugs to automedicate themselves." Arch Gen Psychiatry. 2007;64: 932-940
This blunted response to methylphenidate was linked with symptoms of inattention and higher reports of liking the drug, which suggests that in ADHD, dopamine dysfunction is related to inattention and to a greater risk for drug abuse.
These findings document that the dopamine system, which is very important for modulating attention and motivation, is not working properly in individuals with ADHD. Although ADHD is the most prevalent psychiatric disorder of childhood and has been studied for decades, the specific neurobiological mechanisms underlying this disorder remain unclear. Although research findings point to a disruption in the brain dopamine system in ADHD, for many years there has been a debate about whether dopamine is increased, decreased, or not changed in ADHD.
Compared with the controls, the subjects with ADHD had a significantly smaller decrease in binding of 11C-raclopride in the left and right caudate after methylphenidate, indicating that less dopamine was released in response to methylphenidate in these subjects. This blunted dopamine response to methylphenidate in the caudate in the subjects with ADHD was linked with symptoms of inattention and with higher reports of liking the drug.
Also found was preliminary evidence of reduced 11C-raclopride binding in the hippocampus and the amygdala, which are part of the brain's limbic system that is involved in emotional responses and in memories.
Ritalin or the amphetamine Adderall — are effective treatments for ADHD: they amplify the weak dopamine signals in the brain of individuals with ADHD.
In addition, the findings help elucidate why, compared with members of the general public, individuals with ADHD have a much higher risk of abusing drugs. Drugs of abuse temporarily increase the concentration of dopamine in the brain. People with ADHD are at greater risk of taking drugs, not just because they want to get 'high,' but in their case, it may actually make them feel better. They may end up taking drugs to automedicate themselves." Arch Gen Psychiatry. 2007;64: 932-940