New evidence about the effects of Ritalin, a drug used to treat children with ADD and ADHD, has prompted renewed calls for research into its long-term effects.Dr John Walker and colleagues from the University at Buffalo, State University of New York have found that relatively high doses of the drug methylphenidate, the generic form of Ritalin, changed the expression of a gene involved in brain function in laboratory rats. The same gene is known to be affected in humans by other psychoactive drugs, such as amphetamines and cocaine.
The research was presented this week at the annual meeting of the US Society for Neuroscience.
"Children have been given Ritalin daily for many years, and it is extremely effective and beneficial, but it's not quite as simple as a short-acting drug,It does appear to be safe when used properly, but it is still important to ask what it is doing in the brain."said Dr Walker.
Mice were used in the experiment. One group was given sweetened milk containing Ritalin, and their brains were compared to those of another group given just sweetened milk.According to Dr Walker, the dose used was comparable to the high end of the dose used to treat children with ADD and ADHD, after taking into account differences in metabolism between mice and humans.
The researchers found Ritalin increased the activity of a gene called c-fos in the striatum, a part of the brain involved in movement and motivation. "These data do suggest that there are effects of Ritalin on cell function that outlast the short term and we should sort that out," Dr Walker said.
ADHD researcher Dr Alasdair Vance of Melbourne's Alfred Hospital said the study demonstrated the importance of studying the long-term effects of Ritalin. Dr Vance said that, children with ADHD (attention deficit hyperactivity disorder) and ADD (attention deficit disorder) are believed to have a problem in the parts of the brain that integrate information from different senses.
These children lack the motivation for picking up what's important, and can't seem to block out what's not important. Ritalin is believed to work by increasing the amount of the nerve transmitter dopamine in these parts of the brain.In some children the beneficial effects of Ritalin appeared to decline despite continued medication, he said, adding that there is an enormous need to study the long-term effects of Ritalin on the brains of primary school-aged children.