How does ritalin (methylphenidate) work at the chemical level, in hyperactive children?

Increased inhibition. Hyperactivity in add occurs because inhibitory brain systems are "under active." Ritalin (methylphenidate) appears to work by increasing this inhibitory signal and thus decreasing hyperactivity.
Via two chemicals. Ritalin (methylphenidate) blocks the chemicals Dopamine and noreadrenaline from being taken up into neurones (which is the way these chemicals are cleared) hence making them more available for use and helping to improve attention and concentration.
Increase transmitter. ADHD with hyperactivity is related to a low amount of Dopamine and Nor epinephrin in the brain. Stimulants such as Ritalin (methylphenidate) and amphetamines work by increasing the brain levels of these neurotransmittersm restirubg a balance.

Related Questions

How does a stimulant like ritalin (methylphenidate) work in hyperactive children?

We're not sure. We know that stimulants increase activity of a neuroregulator found mainly in a very old part of the brain in a system whose activation is "rewarding." exactly why that leads to the dramatic improvements seen in many individuals with adhd is still the subject of varied research. One well-established fact: children (with or without adhd) respond similarly to stimulants: they aren't stimulated. Read more...
Focus and Alertness. The stimulant medicines primarily work by increasing focus and attention span. This allows people to make better decisions about what needs to be done and what can be left alone. The result is decreased hyperactivity and a better use of activity level. Also, these medicines help to activate parts of the brain that promote alertness and awareness, which helps increase better judgement. Read more...
Brain under aroused. Children with ADHD have been found to have brain activity that is under aroused or less alert than average. Ritalin (methylphenidate) is a stimulant that increases brain nor epinephrin. This improves brain alertness. Read more...