Many kids with slow processing speed take medication designed to help children with ADHD. Given that more than 60% of children with ADHD display slow processing speed, this is no surprise. Clearly, medication for ADHD is a powerful intervention that is often the first line of treatment for ADHD. But can medication improve slow processing speed?
The most common type of medications used for children with ADHD are methylphenidate and amphetamine, both types of stimulants. Ritalin, Adderall, Concerta, Vyvanse, Dexedrine, and Focalin are stimulant medications widely used in the treatment of ADHD. Other non-stimulant medications such as Strattera and Tenex are prescribed when the stimulants are ineffective or have harsh side effects. When these medications are able to be helpful to kids with ADHD, they tend to improve some of the underlying cognitive skills that contribute to this disorder. Effective use of medication for ADHD results in observable improvement in attention span and reduction in hyperactivity and impulsivity. But can these medications improve slow processing speed?
It appears that stimulant medications may have a positive effect on specific components of processing speed. Studies suggest that stimulant medications may modestly improve reaction time, a basic measure of quick responding, and reduce the variability of reaction time, a commonly observed phenomenon in children with ADHD. While medication may reduce simple reaction time, tasks that require increased attention or executive functioning demands are not consistently improved by stimulant medications.
It appears that stimulant medications improve slow processing speed by increasing the speed at which information is accumulated. During the initial acquisition of information in a task, faster processing speed occurs as a result of the medication. Other studies suggest that stimulant medications can increase processing rates and decrease reaction time in neuropsychological testing conducted with individuals without ADHD. These findings suggest that stimulants might help non-ADHD individuals improve the recognition (identification) and stimulus evaluation (response selection) components of processing speed. Essentially, stimulants help in faster recognition of a problem and make a brain-based decision about action.
Stimulant medications have also been demonstrated to improve “naming speed,” another straightforward measure of processing speed that assesses how quickly one can name aloud objects, pictures, colors, letters, numbers, or symbols. One study suggests that medication improves only color naming speed and not letter or number naming speed, which would argue that stimulant medication might have a minimal impact on reading fluency. However other studies suggest medication can improve both word and non-word decoding accuracy, as well as rapid naming. The current state of the science indicates that stimulants can improve skills in simple processing speed (for individuals with or without ADHD) but are unlikely to be helpful with processing-speed tasks that require the use of more complex executive-functioning skills or that are central to academic performance.
The indirect impact of medication on processing speed is also important to consider. The Davidson Institute describes that processing speed can be boosted by improving activation and focus, thereby increasing the pace of work. Short-term effects of stimulant medication can improve immediate academic performance, helping kids to get their work done more efficiently. However, three-year follow-up studies with a large group of children did not show improved academic performance. But this may not apply to individual children. In my clinical work, I have observed many kids who are far more effective in completing their homework right after school when their medication is still in their system, rather than waiting for the evening when the medication no longer has any effect.
The question of whether to use stimulant medication to improve processing speed is complex. Beyond the concerns of medication side effects, there are many family and philosophical issues to consider. There is strong evidence that stimulant medications can enhance the speed of processing, seen particularly in measures of reaction time, naming speed, and word reading. Stimulant medications may also help in short-term academic tasks and in sustaining attention to tasks that require efficient processing. However, it does not appear that stimulant medications can improve more complex processing of information. Processing tasks that require executive- functioning skills, flexibility, or working memory or that have more involved executive demands do not appear to be improved by stimulant medication. Medication may help with simple processing-speed tasks involving reaction time (identifying stimuli quickly) but not necessarily with some of the productivity required for writing, formulating thoughts, or other tasks that need more in-depth executive and cognitive skills.