Intra-individual response variability assessed by ex-Gaussian analysis may be a new endophenotype for attention-deficit/hyperactivity disorder

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dc.contributor.authorHenríquez-Henríquez, Marcela Patricia
dc.contributor.authorBilleke, Pablo
dc.contributor.authorHenríquez, Hugo
dc.contributor.authorZamorano, Francisco Javier
dc.contributor.authorRothhammer, Francisco
dc.contributor.authorAboitiz, Francisco
dc.date.accessioned2016-01-29T07:42:50Z
dc.date.available2016-01-29T07:42:50Z
dc.date.issued2015
dc.description.abstractIntra-individual variability of response times (RTisv) is considered as potential endophenotype for attentional deficit/hyperactivity disorder (ADHD). Traditional methods for estimating RTisv lose information regarding response times (RTs) distribution along the task, with eventual effects on statistical power. Ex-Gaussian analysis captures the dynamic nature of RTisv, estimating normal and exponential components for RT distribution, with specific phenomenological correlates. Here, we applied ex-Gaussian analysis to explore whether intra-individual variability of RTs agrees with criteria proposed by Gottesman and Gould for endophenotypes. Specifically, we evaluated if normal and/or exponential components of RTs may (a) present the stair-like distribution expected for endophenotypes (ADHD > siblings > typically developing children (TD) without familiar history of ADHD) and (b) represent a phenotypic correlate for previously described genetic risk variants. This is a pilot study including 55 subjects (20 ADHD-discordant sibling-pairs and 15 TD children), all aged between 8 and 13 years. Participants resolved a visual Go/Nogo with 10% Nogo probability. Ex-Gaussian distributions were fitted to individual RT data and compared among the three samples. In order to test whether intra-individual variability may represent a correlate for previously described genetic risk variants, VNTRs at DRD4 and SLC6A3 were identified in all sibling-pairs following standard protocols. Groups were compared adjusting independent general linear models for the exponential and normal components from the ex-Gaussian analysis. Identified trends were confirmed by the non-parametric Jonckheere-Terpstra test. Stair-like distributions were observed for μ (p = 0.036) and σ (p = 0.009). An additional "DRD4-genotype" × "clinical status" interaction was present for τ (p = 0.014) reflecting a possible severity factor. Thus, normal and exponential RTisv components are suitable as ADHD endophenotypes.
dc.identifier.citationHenríquez-Henríquez MP, Billeke P, Henríquez H, Zamorano FJ, Rothhammer F, Aboitiz F. Intra-Individual Response Variability Assessed by Ex-Gaussian Analysis may be a New Endophenotype for Attention-Deficit/Hyperactivity Disorder. Front Psychiatry. 2015 Jan 12;5:197
dc.identifier.urihttp://hdl.handle.net/11447/217
dc.identifier.urihttp://dx.doi.org/10.3389/fpsyt.2014.00197
dc.language.isoen_US
dc.subjectex-Gaussian analysis
dc.subjectADHD
dc.subjectintra-individual variability
dc.subjectendophenotypes
dc.subjectresponse time
dc.titleIntra-individual response variability assessed by ex-Gaussian analysis may be a new endophenotype for attention-deficit/hyperactivity disorder
dc.typeArtículo

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