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Intraindividual variability in inhibitory function in adults with ADHD--an ex-Gaussian approach.

Gmehlin D, Fuermaier AB, Walther S, Debelak R, Rentrop M, Westermann C, Sharma A, Tucha L, Koerts J, Tucha O, Weisbrod M, Aschenbrenner S - PLoS ONE (2014)

Bottom Line: We did not find higher numbers of commission errors in aADHD, while the number of omissions was significantly increased compared with controls.In contrast to increased mean RT, the distributional parameter mu did not document a significant slowing in aADHD.Moreover, we found a significant correlation between tau and the number of omission errors.

View Article: PubMed Central - PubMed

Affiliation: Department of Clinical Psychology and Neuropsychology, SRH Klinikum, Karlsbad-Langensteinbach, Germany.

ABSTRACT

Objective: Attention deficit disorder (ADHD) is commonly associated with inhibitory dysfunction contributing to typical behavioral symptoms like impulsivity or hyperactivity. However, some studies analyzing intraindividual variability (IIV) of reaction times in children with ADHD (cADHD) question a predominance of inhibitory deficits. IIV is a measure of the stability of information processing and provides evidence that longer reaction times (RT) in inhibitory tasks in cADHD are due to only a few prolonged responses which may indicate deficits in sustained attention rather than inhibitory dysfunction. We wanted to find out, whether a slowing in inhibitory functioning in adults with ADHD (aADHD) is due to isolated slow responses.

Methods: Computing classical RT measures (mean RT, SD), ex-Gaussian parameters of IIV (which allow a better separation of reaction time (mu), variability (sigma) and abnormally slow responses (tau) than classical measures) as well as errors of omission and commission, we examined response inhibition in a well-established GoNogo task in a sample of aADHD subjects without medication and healthy controls matched for age, gender and education.

Results: We did not find higher numbers of commission errors in aADHD, while the number of omissions was significantly increased compared with controls. In contrast to increased mean RT, the distributional parameter mu did not document a significant slowing in aADHD. However, subjects with aADHD were characterized by increased IIV throughout the entire RT distribution as indicated by the parameters sigma and tau as well as the SD of reaction time. Moreover, we found a significant correlation between tau and the number of omission errors.

Conclusions: Our findings question a primacy of inhibitory deficits in aADHD and provide evidence for attentional dysfunction. The present findings may have theoretical implications for etiological models of ADHD as well as more practical implications for neuropsychological testing in aADHD.

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Related in: MedlinePlus

Distribution of age for both adult controls and adult ADHD.
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pone-0112298-g002: Distribution of age for both adult controls and adult ADHD.

Mentions: Given the large age range in our sample, the corresponding distribution is illustrated in Figure 2.


Intraindividual variability in inhibitory function in adults with ADHD--an ex-Gaussian approach.

Gmehlin D, Fuermaier AB, Walther S, Debelak R, Rentrop M, Westermann C, Sharma A, Tucha L, Koerts J, Tucha O, Weisbrod M, Aschenbrenner S - PLoS ONE (2014)

Distribution of age for both adult controls and adult ADHD.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4257533&req=5

pone-0112298-g002: Distribution of age for both adult controls and adult ADHD.
Mentions: Given the large age range in our sample, the corresponding distribution is illustrated in Figure 2.

Bottom Line: We did not find higher numbers of commission errors in aADHD, while the number of omissions was significantly increased compared with controls.In contrast to increased mean RT, the distributional parameter mu did not document a significant slowing in aADHD.Moreover, we found a significant correlation between tau and the number of omission errors.

View Article: PubMed Central - PubMed

Affiliation: Department of Clinical Psychology and Neuropsychology, SRH Klinikum, Karlsbad-Langensteinbach, Germany.

ABSTRACT

Objective: Attention deficit disorder (ADHD) is commonly associated with inhibitory dysfunction contributing to typical behavioral symptoms like impulsivity or hyperactivity. However, some studies analyzing intraindividual variability (IIV) of reaction times in children with ADHD (cADHD) question a predominance of inhibitory deficits. IIV is a measure of the stability of information processing and provides evidence that longer reaction times (RT) in inhibitory tasks in cADHD are due to only a few prolonged responses which may indicate deficits in sustained attention rather than inhibitory dysfunction. We wanted to find out, whether a slowing in inhibitory functioning in adults with ADHD (aADHD) is due to isolated slow responses.

Methods: Computing classical RT measures (mean RT, SD), ex-Gaussian parameters of IIV (which allow a better separation of reaction time (mu), variability (sigma) and abnormally slow responses (tau) than classical measures) as well as errors of omission and commission, we examined response inhibition in a well-established GoNogo task in a sample of aADHD subjects without medication and healthy controls matched for age, gender and education.

Results: We did not find higher numbers of commission errors in aADHD, while the number of omissions was significantly increased compared with controls. In contrast to increased mean RT, the distributional parameter mu did not document a significant slowing in aADHD. However, subjects with aADHD were characterized by increased IIV throughout the entire RT distribution as indicated by the parameters sigma and tau as well as the SD of reaction time. Moreover, we found a significant correlation between tau and the number of omission errors.

Conclusions: Our findings question a primacy of inhibitory deficits in aADHD and provide evidence for attentional dysfunction. The present findings may have theoretical implications for etiological models of ADHD as well as more practical implications for neuropsychological testing in aADHD.

Show MeSH
Related in: MedlinePlus