Abstract
Attention-Deficit/Hyperactivity Disorder (ADHD) is a phenotipically and neurobiologically heterogeneous disorder. Deficiencies at different levels in response inhibition, differences in dopamine transporter genotype (DAT1) and various symptomatic presentations contribute to ADHD heterogeneity. Integrating these three aspects into a functional neuroimaging research could help unreval specific neurobiological components of more phenotipically homogeneous groups of patients with ADHD. During the Go-NoGo trial, we investigated the effect of the DAT1 gene using 3 T MRI in 72 ADHD cases and 24 (TD) controls that typically developed between the ages 8 and 15 years. In the total ADHD group, DAT1 predicted homozygosity for the 10R allele and hypoactivation in the anterior cingulate cortex and paracingulate cortex. There were no significant activation differences between DAT1 10R/10R homozygotes and 9R carriers in TD controls. Subjects with predominantly inattentive ADHD (ADHD-I) presentation with DAT1 10R/10R homozygous reduced neuronal activation during Go trial particularly in the frontal regions and insular cortex, and in the parietal regions during NoGo trial (brain regions reported as part of Default Mode Network- DMN). Additionally, DAT1 10R/10R homozygousness was associated with increased occipital zone activation during only the Go trial in the ADHD combined presentation (ADHD-C) group. Our results point the three main findings: 1) The DAT1 gene is 10R homozygous for differentiated brain activation in ADHD cases but not in the TD controls, supporting the DAT1 gene as a potential marker for ADHD, 2) The relationship between the DAT1 gene and the occipital regions in ADHD-C group which may reflect compensatory mechanisms, 3) The relationship between DAT1 gene and the reduced DMN suppression for 9R carriers probabaly stems from the ADHD-I group.
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We thank Dr. Cahide Aydın for contributions to the case enrollment process.
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This work was partially supported by research grants from the following: Ege University Scientific Research Project Commission, Izmir, Turkey; the National Council for Scientific and Technological Development (CNPq, Brazil); and Hospital de Clinicas de Porto Alegre (HCPA), Porto Alegre, Brazil. No financial or material support was received for this study.
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E.S.E and L.A.R. designed the protocol of the study. A.B., S.S and K.U.Y. contributed to the case selection procedure and data collection. D.A. and B.K. were responsible for the genetic part of the study. C.C. provided neuroimaging part of the study. G.U.B. drafted the article, E.S.E. revised it critically for intellectual content. All authors approved final version of the manuscript.
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After the study procedures were described, the participants’ parents provided written informed consent. The Ethics Committee of Ege University in Turkey approved the study protocol.
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Eyüp Sabri Ercan is on the advisory board of Sanofi Turkey. L. A. Rohde received grant or research support and served as a consultant and on the speakers’ bureaus of Eli Lilly and Co., Janssen, Medice, Novartis and Shire. The ADHD and Juvenile Bipolar Disorder Outpatient Programs chaired by Dr. Rohde received unrestricted educational and research support from the following pharmaceutical companies: Janssen, Novartis, and Shire. Dr. Rohde received travel grants from Shire to participate in the 2015 WFADHD congress. He received royalties from Artmed Editora and Oxford University Press. The other authors declare that they have no conflicts of interest to report.
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Bacanlı, A., Unsel-Bolat, G., Suren, S. et al. Effects of the dopamine transporter gene on neuroimaging findings in different attention deficit hyperactivity disorder presentations. Brain Imaging and Behavior 15, 1103–1114 (2021). https://doi.org/10.1007/s11682-020-00437-w
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DOI: https://doi.org/10.1007/s11682-020-00437-w