Nav: Home

ADHD medication: How much is too much for a hyperactive child?

September 09, 2019

When children with ADHD don't respond well to Methylphenidate (MPH, also known as Ritalin) doctors often increase the dose. Now a new review shows that increasing the dose may not always be the best option, as it may have no effect on some of the functional impairments associated with ADHD. The researchers caution against increasing the doses is based on findings that this effect may only be observed for behavioral factors (such as reduction in attention and/or hyperactivity/impulsivity) and not for the child's ability to control their impulses. This work is presented at the ECNP Conference in Copenhagen.

Attention-Deficit/Hyperactivity Disorder (ADHD), is the most common childhood-onset psychiatric disorder, characterized by symptoms such as inattention, hyperactivity and impulsivity. Worldwide, around 5% of children and adolescents suffer from ADHD*.

ADHD is a complex condition comprising both behavioural and neurocognitive symptoms, but diagnosis requires only that a patient exhibit at least 6 behavioural symptoms. You can see a list of these symptoms at: https://www.nhs.uk/conditions/attention-deficit-hyperactivity-disorder-adhd/symptoms/. Treatment is normally judged on how well these behavioural symptoms are improved. However, children with ADHD can also be characterized, by looking at functional impairments such as neurocognitive functioning, including inhibitory control which is a measure of how they keep their impulsiveness under control.

Methylphenidate (MPH) has been commonly used as a first line medication to treat children with ADHD since the 1990s. It is generally effective and well tolerated, but around 30% of children taking MPH don't respond to standard doses, often leading doctors to consider increasing the dose.

Like all drugs, MPH carries the risk of side effects, which may become more significant at increased dose and with long-term use. These side effects include growth retardation and difficulty in gaining weight: 3 years of MPH use can cause a child to be 2cm shorter and 2.7 kg lighter than normal.

To understand and distil the effects of the drug on children with ADHD, Karen Vertessen (MD & PhD student at the Vrije Universiteit Amsterdam) and colleagues undertook a review of all the scientific literature (a metanalysis) relating to dose effects of MPH on inhibitory control (an aspect of impulsiveness) in children and adolescents.

They managed to identify 18 studies, comprising in total 606 subjects with ADHD. They were able to classify the MPH doses reported as low, medium, or high dose. Results showed that a medium dose of MPH had the strongest beneficial effects on inhibitory control. However increasing the dose past the medium dose did not make the drug work more effectively.

Karen Vertessen said, "Scientifically, this is an interesting result. Generally, high doses of MPH does not help the child or adolescent keep their inhibitions under better control, although an increased dose, in general ,does have a greater effect on the core behavioral symptoms of ADHD.

Even though inhibitory control is just one aspect of impulsivity, we suggest that medically we need to be cautious about just increasing the dose when a child does not instantly respond to the drugs. Children are more vulnerable than adults in these cases, especially since they will be just beginning to receive treatment, and so many treatment variables will still need to be established. If clinicians decide to start therapy with MPH, they need to keep a close eye on the patient and objectively evaluate every dose, to make sure that the higher dose is actually having an effect. Current ADHD evaluation only uses behavioral outcomes, whereas we suggest adding neurocognitive outcomes to this evaluation, given that these outcomes are important for, among others, academic functioning. In other words, checking for whether or not MPH is dealing with inhibitory control might allow us to see if increasing the dose makes sense. To see to what extent these findings might have a clinical impact we are currently investigating the other most relevant neurocognitive factors related to ADHD".

Commenting, Dr Kerstin von Plessen (Centre Hospitalier Universitaire Vaudois, Lausanne) said:

"This is an elegant and highly relevant study, which sheds light on an interesting phenomenon which has not received sufficient attention up to now. However the study does not address the question why some children receive this higher dosage. This is probably due to the lower dose having a lesser effect. This means that the findings agree with the clinical reality telling us that children, who do not respond sufficiently to the regular dosages of MPH, require a second more comprehensive diagnostic examination before increasing the medication. In addition, not all children respond to MPH, and so other treatment options should also be explored. The conclusion of the study, that we should add neurocognitive tests to the evaluation, may be a highly useful option to further identify academic capacity and behaviour, but should not be a substitute for the clinical evaluation of impulsivity (inhibitory control) during any change of medication."

This is an independent comment: Dr von Plessen was not involved in this work.
-end-
* Polanczyk G , de Lima MS , Horta BL , et al: The worldwide prevalence of ADHD: a systematic review and metaregression analysis. Am J Psychiatry 164(6):942-948, 2007. See also USA statistics, Centre for Disease Control, https://www.cdc.gov/ncbddd/adhd/data.html

**See https://www.ncbi.nlm.nih.gov/pubmed/21970086

European College of Neuropsychopharmacology

Related Adhd Articles:

Autism and ADHD share genes
Researchers from the national psychiatric project iPSYCH have found that autism and ADHD share changes in the same genes.
ADHD across racial/ethnic groups
This study of patients from diverse racial/ethnic backgrounds who received care at the Kaiser Permanente Northern California health system looked at how common attention-deficit/hyperactivity disorder (ADHD) diagnoses were over a 10-year period across seven racial/ethnic groups.
Cycles of reward: New insight into ADHD treatment
Researchers at the Okinawa Institute of Science and Technology Graduate University (OIST) in collaboration with scientists at the University of Otago and the University of Auckland in New Zealand, investigated the actions of the drug in rats.
Young mums more likely to have kids with ADHD
Young mothers have a greater chance of having a child with attention deficit hyperactivity disorder (ADHD) according to new research from the University of South Australia.
ADHD medication: How much is too much for a hyperactive child?
When children with ADHD don't respond well to Methylphenidate (MPH, also known as Ritalin) doctors often increase the dose.
Antipsychotic use in youths with ADHD is low, but still cause for concern
A new study eased fears about the proportion of youths with ADHD taking antipsychotic drugs, but still found that many prescriptions may be inappropriate.
How stimulant treatment prevents serious outcomes of ADHD
Analysis quantifies the extent which stimulant treatment reduces serious outcomes in children and young adults with ADHD.
Did Leonardo da Vinci have ADHD?
Leonardo da Vinci produced some of the world's most iconic art, but historical accounts show that he struggled to complete his works.
More sleep may help teens with ADHD focus and organize
Teenagers with attention deficit hyperactivity disorder (ADHD) may benefit from more sleep to help them focus, plan and control their emotions.
Researchers have found the first risk genes for ADHD
A major international collaboration headed by researchers from the Danish iPSYCH project, the Broad Institute of Harvard and MIT, Massachusetts General Hospital, SUNY Upstate Medical University, and the Psychiatric Genomics Consortium has for the first time identified genetic variants which increase the risk of ADHD.
More Adhd News and Adhd Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#543 Give a Nerd a Gift
Yup, you guessed it... it's Science for the People's annual holiday episode that helps you figure out what sciency books and gifts to get that special nerd on your list. Or maybe you're looking to build up your reading list for the holiday break and a geeky Christmas sweater to wear to an upcoming party. Returning are pop-science power-readers John Dupuis and Joanne Manaster to dish on the best science books they read this past year. And Rachelle Saunders and Bethany Brookshire squee in delight over some truly delightful science-themed non-book objects for those whose bookshelves are already full. Since...
Now Playing: Radiolab

An Announcement from Radiolab