Title: Methylphenidate Decreased the Amount of Glucose Needed by the Brain to Perform a Cognitive Task

Abstract

The use of stimulants (methylphenidate and amphetamine) as cognitive enhancers by the general public is increasing and is controversial. It is still unclear how they work or why they improve performance in some individuals but impair it in others. To test the hypothesis that stimulants enhance signal to noise ratio of neuronal activity and thereby reduce cerebral activity by increasing efficiency, we measured the effects of methylphenidate on brain glucose utilization in healthy adults. We measured brain glucose metabolism (using Positron Emission Tomography and 2-deoxy-2[18F]fluoro-D-glucose) in 23 healthy adults who were tested at baseline and while performing an accuracy-controlled cognitive task (numerical calculations) given with and without methylphenidate (20 mg, oral). Sixteen subjects underwent a fourth scan with methylphenidate but without cognitive stimulation. Compared to placebo methylphenidate significantly reduced the amount of glucose utilized by the brain when performing the cognitive task but methylphenidate did not affect brain metabolism when given without cognitive stimulation. Whole brain metabolism when the cognitive task was given with placebo increased 21% whereas with methylphenidate it increased 11% (50% less). This reflected both a decrease in magnitude of activation and in the regions activated by the task. Methylphenidate’s reduction of the metabolic increases in regionsmore » from the default network (implicated in mind-wandering) was associated with improvement in performance only in subjects who activated these regions when the cognitive task was given with placebo. These results corroborate prior findings that stimulant medications reduced the magnitude of regional activation to a task and in addition document a ‘‘focusing’’ of the activation. This effect may be beneficial when neuronal resources are diverted (i.e., mind-wandering) or impaired (i.e., attention deficit hyperactivity disorder), but it could be detrimental when brain activity is already optimally focused. This would explain why methylphenidate has beneficial effects in some individuals and contexts and detrimental effects in others.« less

Authors:

Volkow, Nora D. ^[1]; Fowler, Joanna S. ^[2]; Wang, Gene-Jack ^[2]; Telang, Frank ^[3]; Logan, Jean ^[2]; Wong, Christopher ^[2]; Ma, Jim ^[3]; Pradhan, Kith ^[2]; Benveniste, Helene ^[2]; Swanson, James M. ^[4]

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+ Show Author Affiliations

1. National Inst. on Drug Abuse, Bethesda, MD (United States); National Inst. on Alcohol Abuse and Alcoholism, Bethesda, MD (United States)
2. Brookhaven National Lab. (BNL), Upton, NY (United States). Medical Dept.
3. National Inst. on Alcohol Abuse and Alcoholism, Bethesda, MD (United States)
4. Univ. of California, Irvine, CA (United States). Child Development Center

Publication Date:

Wed Apr 16 00:00:00 EDT 2008

Research Org.:

Associated Universities, Inc., Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER). Biological Systems Science Division

OSTI Identifier:

1627345

Grant/Contract Number:  

AC02-76CH00016

Resource Type:

Accepted Manuscript

Journal Name:

PLoS ONE

Additional Journal Information:

Journal Volume: 3; Journal Issue: 4; Journal ID: ISSN 1932-6203

Publisher:

Public Library of Science

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; Science & Technology - Other Topics