For decades, stimulants have been used to treat attention deficit hyperactivity disorder (ADHD) in adolescents, improving a wide range of cognitive functions. Researchers, however, were not clear as to the mechanisms causing efficiency in the use of stimulants.
In a new study, conducted at The State University of New York at Buffalo, researchers cleared up some speculation on how the use of certain stimulants, like methylphenidate (MPH), reforms cognitive functions to diminish symptoms.
“This is the first study to demonstrate that improving short-term working memory and the ability to inhibit are at least part of the way that stimulants work and improve outcomes for ADHD in the classroom,” said Larry Hawk, the study’s lead author.
Recognizing the mechanisms involved in the treatment of the neurodevelopmental disorder is crucial, as it could aid in the development of more efficient treatment, both pharmacological and behavioural, with fewer side effects, researchers say.
“Knowing how one treatment works gives us clues about what to target in developing new treatments. That can save a lot of time, energy and money,” said Hawk.
With that notion in mind, researchers examined the cognitive functions of 82 children over a one-week period, combining both clinical and laboratory processes. The participants completed computerized assessments, in addition to physical activities, such as games, sports, arts, and math assignments.
During the study, each child was given either a low-to-moderate dose of a stimulant medication or a placebo. Researchers then examined the participants’ response to the medication, taking into account improved classroom behavior and academic literacy.
According to the results, the stimulant drug methylphenidate significantly improved problematic behaviour and performance in the classroom. The treatment also strengthened certain cognitive functions.
“Specifically, the more medication helped kids hold and manipulate information in working memory (like being able to remember things in reverse order) and the more it helped children inhibit responses ‘on the fly’, the greater the classroom benefit. These data are the strongest yet to suggest those are the mechanisms by which the medication is working,” said Hawk.
The findings may also pave the way for new treatment of basic cognitive processes without pharmacological intervention, which targets the working memory, thus strengthening cognitive processes indirectly.
“Behavioural treatment and parent training may strengthen these cognitive processes indirectly,” Hawk suggested. “Both can be used to enhance executive function – and behaviour – by systematically and gradually reinforcing greater and greater self-control. Whether that is how these treatments work, or whether they would work even better if they directly targeted working memory and inhibition, remains to be seen.”
The findings were published in the Journal of Child Psychology and Psychiatry.