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Molecular Psychiatry (2011) 16, 11471154& 2011 Macmillan Publishers Limited All rights reserved 1359-4184/11
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ORIGINAL ARTICLE
Motivation deficit in ADHD is associated with dysfunction of the dopamine reward pathway
ND Volkow1,2, G-J Wang3,4,5, JH Newcorn5, SH Kollins6, TL Wigal7, F Telang2, JS Fowler3,4,5, RZ Goldstein3,4, N Klein3,4, J Logan3,4, C Wong3,4 and JM Swanson7
1National Institute on Drug Abuse, Bethesda, MD, USA; 2Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA; 3Medical Department, Brookhaven National Laboratory, Upton, NY, USA; 4Chemistry Department, Brookhaven National Laboratory, Upton, NY, USA; 5Department of Psychiatry, Mount Sinai Medical Center, New York, NY, USA; 6Department of Psychiatry, Duke University Medical Center, Durham, NC, USA and 7Child Development Center, University of California, Irvine, CA, USA
Attention-deficit hyperactivity disorder (ADHD) is typically characterized as a disorder of inattention and hyperactivity/impulsivity but there is increasing evidence of deficits in motivation. Using positron emission tomography (PET), we showed decreased function in the brain dopamine reward pathway in adults with ADHD, which, we hypothesized, could underlie the motivation deficits in this disorder. To evaluate this hypothesis, we performed secondary analyses to assess the correlation between the PET measures of dopamine D2/D3 receptor and dopamine transporter availability (obtained with [11C]raclopride and [11C]cocaine, respectively) in the dopamine reward pathway (midbrain and nucleus accumbens) and a surrogate measure of trait motivation (assessed using the Achievement scale on the Multidimensional Personality Questionnaire or MPQ) in 45 ADHD participants and 41 controls. The Achievement scale was lower in ADHD participants than in controls (115 vs 143, P < 0.001) and was significantly correlated with D2/D3 receptors (accumbens: r = 0.39, P < 0.008; midbrain: r = 0.41, P < 0.005) and transporters (accumbens: r = 0.35, P < 0.02) in ADHD participants, but not in controls. ADHD participants also had lower values in the Constraint factor and higher values in the Negative Emotionality factor of the MPQ but did not differ in the Positive Emotionality factorand none of these were correlated with the dopamine measures. In ADHD participants, scores in the Achievement scale were also negatively correlated with symptoms of inattention (CAARS A, E and SWAN I). These findings provide evidence that disruption of the dopamine reward pathway is associated with motivation deficits in...