Featured Research

from universities, journals, and other organizations

How Do ADHD Medications Work?

Date:
October 16, 2013
Source:
Elsevier
Summary:
There is a swirling controversy regarding the suspicion that medications prescribed for the treatment of ADHD (attention-deficit/hyperactivity disorder) primarily act to control disruptive behavior as opposed to having primary effects on the ability to attend to the environment. A new study now provides evidence that methylphenidate and atomoxetine, two FDA-approved medications for the treatment of ADHD, both improve the brain's activation when attempting to make fine temporal distinctions, but have differential effects on performance.

There is a swirling controversy regarding the suspicion that medications prescribed for the treatment of ADHD (attention-deficit/hyperactivity disorder) primarily act to control disruptive behavior as opposed to having primary effects on the ability to attend to the environment. Thus, there is a continued need to better understand the neural basis of ADHD medication effects.

A new study in Biological Psychiatry now provides evidence that methylphenidate and atomoxetine, two FDA-approved medications for the treatment of ADHD, both improve the brain's activation when attempting to make fine temporal distinctions, but have differential effects on performance.

Time estimation, and particularly temporal discrimination, is impaired in individuals diagnosed with ADHD. Additionally, research using imaging scans show that the brain is under-activated when they perform such cognitive tasks.

This led researchers at King's College London to evaluate and compare stimulant and non-stimulant treatments for ADHD in the way they affect performance and brain activation. They recruited twenty adolescent males with ADHD who underwent 3 imaging scans while performing a time discrimination task after receiving single doses of methylphenidate, atomoxetine, and placebo, each administered one week apart. They also compared those results with a control group of 20 healthy males.

First author Dr. Anna Smith explains their findings: "We show here that the stimulant methylphenidate acts quickly with immediate effects upon performance on a timing task we know children with ADHD find challenging. Crucially however, acute doses of either methylphenidate or the non-stimulant atomoxetine increase brain activation in the frontal lobes, typically under-recruited in children with ADHD, so that these key under-functioning frontal brain regions operate at the normal levels seen in other children."

"This exciting finding suggests that both stimulants and non-stimulants share similar mechanisms of action and are both comparable in the way they normalise the activity of important frontal brain regions in children with ADHD. This could explain why both types of drug improve behaviour in children with ADHD, namely by normalizing the reduced activity in the frontal lobes that typifies the disorder," she added.

Methylphenidate and atomoxetine are interesting drugs to compare. Methylphenidate blocks both norepinephrine and dopamine transporters, while atomoxetine blocks only the norepinephrine transporter.

On the surface, this study appears to be a comparison of the role of dopamine and norepinephrine systems in the regulation of attention. However, norepinephrine transporters also contribute to the inactivation of dopamine in the cortex. Thus, this study might be seen as comparing two drugs that potently block norepinephrine uptake, but which differ in the extent to which they raise cortical dopamine levels.

"From this perspective, it is interesting that both drugs enhanced cortical activation during temporal discrimination, but only methylphenidate improved behavior. The reason for this dissociation is unknown," said Dr. John Krystal, Editor of Biological Psychiatry. "We cannot tell whether this is related to the extent to which dopamine is raised in the cortex or whether raising dopamine levels in other brain regions is important. Nonetheless, the findings appear to suggest that methylphenidate influences ADHD-related behaviors more potently than does atomoxetine."


Story Source:

The above story is based on materials provided by Elsevier. Note: Materials may be edited for content and length.


Journal Reference:

  1. Anna Smith, Ana Cubillo, Nadia Barrett, Vincent Giampietro, Andrew Simmons, Mick Brammer, Katya Rubia. Neurofunctional Effects of Methylphenidate and Atomoxetine in Boys with Attention-Deficit/Hyperactivity Disorder During Time Discrimination. Biological Psychiatry, 2013; 74 (8): 615 DOI: 10.1016/j.biopsych.2013.03.030

Cite This Page:

Elsevier. "How Do ADHD Medications Work?." ScienceDaily. ScienceDaily, 16 October 2013. <www.sciencedaily.com/releases/2013/10/131016100222.htm>.
Elsevier. (2013, October 16). How Do ADHD Medications Work?. ScienceDaily. Retrieved September 20, 2014 from www.sciencedaily.com/releases/2013/10/131016100222.htm
Elsevier. "How Do ADHD Medications Work?." ScienceDaily. www.sciencedaily.com/releases/2013/10/131016100222.htm (accessed September 20, 2014).

Share This



More Health & Medicine News

Saturday, September 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Sierra Leone's Nationwide Ebola Curfew Underway

Sierra Leone's Nationwide Ebola Curfew Underway

Newsy (Sep. 20, 2014) Sierra Leone is locked down as aid workers and volunteers look for new cases of Ebola. Video provided by Newsy
Powered by NewsLook.com
Changes Found In Brain After One Dose Of Antidepressants

Changes Found In Brain After One Dose Of Antidepressants

Newsy (Sep. 19, 2014) A study suggest antidepressants can kick in much sooner than previously thought. Video provided by Newsy
Powered by NewsLook.com
Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins