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Am J Psychiatry. 2004 Jul;161(7):1173-80. Related Articles, Links
Evidence that methylphenidate enhances the saliency of a
mathematical task by increasing dopamine in the human brain.
Volkow ND, Wang GJ, Fowler JS, Telang F, Maynard L, Logan J,
Gatley SJ, Pappas N, Wong C, Vaska P, Zhu W, Swanson JM.
OBJECTIVE: Methylphenidate is the most commonly prescribed
drug for attention deficit hyperactivity disorder (ADHD),
yet its therapeutic mechanisms are poorly understood. The
objective of this study was to assess if methylphenidate, by
increasing dopamine (neurotransmitter involved in
motivation) in brain, would enhance the saliency of an
academic task, making it more interesting. METHOD: Healthy
subjects (N=16) underwent positron emission tomography with
[(11)C]raclopride (dopamine D(2) receptor radioligand that
competes with endogenous dopamine for binding) to assess the
effects of oral methylphenidate (20 mg) on extracellular
dopamine in the striatum. The authors compared the effects
of methylphenidate during an academic task (solving
mathematical problems with monetary reinforcement) and a
neutral task (passively viewing cards with no remuneration).
In parallel, the effects of methylphenidate on the interest
that the academic task elicited were also evaluated.
RESULTS: Methylphenidate, when coupled with the mathematical
task, significantly increased extracellular dopamine, but
this did not occur when coupled with the neutral task. The
mathematical task did not increase dopamine when coupled
with placebo. Subjective reports about interest and
motivation in the mathematical task were greater with
methylphenidate than with placebo and were associated with
dopamine increases. CONCLUSIONS: The significant association
between methylphenidate-induced dopamine increases and the
interest and motivation for the task confirms the prediction
that methylphenidate enhances the saliency of an event by
increasing dopamine. The enhanced interest for the task
could increase attention and improve performance and could
be one of the mechanisms underlying methylphenidate's
therapeutic effects. These findings support educational
strategies that make schoolwork more interesting as
nonpharmacological interventions to treat ADHD.
PMID: 15229048 [PubMed - in process]
Evidence that methylphenidate enhances the saliency of a
mathematical task by increasing dopamine in the human brain.
Volkow ND, Wang GJ, Fowler JS, Telang F, Maynard L, Logan J,
Gatley SJ, Pappas N, Wong C, Vaska P, Zhu W, Swanson JM.
OBJECTIVE: Methylphenidate is the most commonly prescribed
drug for attention deficit hyperactivity disorder (ADHD),
yet its therapeutic mechanisms are poorly understood. The
objective of this study was to assess if methylphenidate, by
increasing dopamine (neurotransmitter involved in
motivation) in brain, would enhance the saliency of an
academic task, making it more interesting. METHOD: Healthy
subjects (N=16) underwent positron emission tomography with
[(11)C]raclopride (dopamine D(2) receptor radioligand that
competes with endogenous dopamine for binding) to assess the
effects of oral methylphenidate (20 mg) on extracellular
dopamine in the striatum. The authors compared the effects
of methylphenidate during an academic task (solving
mathematical problems with monetary reinforcement) and a
neutral task (passively viewing cards with no remuneration).
In parallel, the effects of methylphenidate on the interest
that the academic task elicited were also evaluated.
RESULTS: Methylphenidate, when coupled with the mathematical
task, significantly increased extracellular dopamine, but
this did not occur when coupled with the neutral task. The
mathematical task did not increase dopamine when coupled
with placebo. Subjective reports about interest and
motivation in the mathematical task were greater with
methylphenidate than with placebo and were associated with
dopamine increases. CONCLUSIONS: The significant association
between methylphenidate-induced dopamine increases and the
interest and motivation for the task confirms the prediction
that methylphenidate enhances the saliency of an event by
increasing dopamine. The enhanced interest for the task
could increase attention and improve performance and could
be one of the mechanisms underlying methylphenidate's
therapeutic effects. These findings support educational
strategies that make schoolwork more interesting as
nonpharmacological interventions to treat ADHD.
PMID: 15229048 [PubMed - in process]
