In the United States, a popular drug to treat ADHD is Ritalin. It is estimated that as many as 10% of the children in the U.S. now take Ritalin or another stimulant , and the U.S. consumes 90% of the Ritalin being manufactured worldwide. Since ADHD children suffer from a reduced number of dopamine receptors in the brain , it is hypothesized that Ritalin is effective because it prevents the reuptake of dopamine and allows it to stay in the intercellular spaces for a substantially longer time.
Ritalin has a calming effect on ADHD children. This is understandable since Ritalin both increases the bioavailability of dopamine and suppresses insulin's ability to block fat release from storage sites; i.e., it accomplishes the same two goals that random movements try to accomplish. However, children on Ritalin complain that it results in an initial burst of energy with a racing heart, followed by a period of physical exhaustion (, p. 112). The energy burst is associated with the adrenaline rush, and the exhaustion is likely a consequence of depleted supplies of both fats and glucose, once the Ritalin has worn off.
Dopamine is a precursor to adrenaline, the "fight or flight" hormone. If dopamine is allowed to linger longer in a bioavailable state through the action of Ritalin, then adrenaline levels will go up. Adrenaline is a very powerful hormone with diverse effects on the body, mainly aimed at increasing fuel supply to the blood in the short term, i.e., to operate in crisis mode.
One crucial effect adrenaline has is to disable insulin's suppressive effect on the fat cells . This allows them to release their fats even while insulin levels are high. Ritalin thus enables the brain to be simultaneously well supplied with glucose for fuel, fat for nerve fiber construction, and dopamine to control execution of the focus and memory consolidation tasks involved with learning new knowledge.
Through its effect of increasing adrenaline levels, Ritalin also suppresses appetite. In the "fight or flight" reaction, the digestive system is shut down, in order to conserve energy, since the digestion process itself consumes energy. Nearly all ADHD children on Ritalin lose weight, and many become dangerously thin over time. A positive effect of reduced appetite is that it likely leads to an increase in the bias towards glucose consumption and fat conservation, as I argued in the section on anorexia. However, in the long term, the depleted fat reserves eventually further aggravate the original problem of insufficient fat supply.