Neural substrates of behavioral variability in attention deficit hyperactivity disorder: based on ex-Gaussian reaction time distribution and diffusion spectrum imaging tractography. Issue 8 (June 2014)

• Record Type: Journal Article
• Authors: Lin, H.-Y.; Gau, S. S.-F.; Huang-Gu, S. L.; Shang, C.-Y.; Wu, Y.-H.; Tseng, W.-Y. I.
• Is Part Of: Psychological medicine. Volume 44:Issue 8(2014)
• Page Start: 1751
• Page End: 1764
• Publication Date: 2014-06
• Subjects: Psychiatry -- Periodicals; Medicine and psychology -- Periodicals; Clinical psychology -- Periodicals; 616.89
• DOI: 10.1017/S0033291713001955
• Languages: English
• ISSNs: 0033-2917

Abstract

<abstract abstract-type="normal"> <title> <x content-type="archive" xml:space="preserve">Abstract</x> </title> <sec id="sec_a1"> <title>Background</title> <p>Increased intra-individual variability (IIV) in reaction time (RT) across various tasks is one ubiquitous neuropsychological finding in attention deficit hyperactivity disorder (ADHD). However, neurobiological underpinnings of IIV in individuals with ADHD have not yet been fully delineated. The ex-Gaussian distribution has been proved to capture IIV in RT. The authors explored the three parameters [<italic>μ</italic> (mu), <italic>σ</italic> (sigma), <italic>τ</italic> (tau)] of an ex-Gaussian RT distribution derived from the Conners' continuous performance test (CCPT) and their correlations with the microstructural integrity of the frontostriatal–caudate tracts and the cingulum bundles.</p> </sec> <sec id="sec_a2" sec-type="methods"> <title>Method</title> <p>We assessed 28 youths with ADHD (8–17 years; 25 males) and 28 age-, sex-, IQ- and handedness-matched typically developing (TD) youths using the CCPT, Wechsler Intelligence Scale for Children, 3rd edition and magnetic resonance imaging (MRI). Microstructural integrity, indexed by generalized fractional anisotropy (GFA), was measured by diffusion spectrum imaging tractrography on a 3-T MRI system.</p> </sec> <sec id="sec_a3" sec-type="results"> <title>Results</title> <p>Youths with ADHD had larger <italic>σ</italic> (<sc>s.d.</sc> of Gaussian distribution) and <italic>τ</italic> (mean of exponential distribution) and reduced GFA in four bilateral frontostriatal tracts. With increased inter-stimulus intervals of CCPT, the magnitude of greater <italic>τ</italic> in ADHD than TD increased. In ADHD youths, the cingulum bundles and frontostriatal integrity were associated with three ex-Gaussian parameters and with <italic>μ</italic> (mean of Gaussian distribution) and <italic>τ</italic>, respectively; while only frontostriatal GFA was associated with <italic>μ</italic> and <italic>τ</italic> in TD youths.</p> </sec> <sec id="sec_a4" sec-type="conclusion"> <title>Conclusions</title> <p>Our findings suggest the crucial role of the integrity of the cingulum bundles in accounting for IIV in ADHD. Involvement of different brain systems in mediating IIV may relate to a distinctive pathophysiological processing and/or adaptive compensatory mechanism.</p> </sec> </abstract>