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Neurocognitive intra-individual variability in mood disorders: effects on attentional response time distributions

Lookup NU author(s): Dr Peter Gallagher, Jonna Nilsson, Dr Andreas Finkelmeyer, Dr Karine MacRitchie, Dr Adrian Lloyd, Jill Thompson, Dr Richard Porter, Professor Allan Young, Emeritus Professor Nicol Ferrier, Professor Hamish McAllister-Williams, Dr Stuart Watson

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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


Abstract

Background. Attentional impairment is a core cognitive feature of major depressive disorder (MDD) and bipolar disorder (BD). However, little is known of the characteristics of response time (RT) distributions from attentional tasks. This is crucial to furthering our understanding of the profile and extent of cognitive intra-individual variability (IIV) in mood disorders. Method. A computerized sustained attention task was administered to 138 healthy controls and 158 patients with a mood disorder: 86 euthymic BD, 33 depressed BD and 39 medication-free MDD patients. Measures of IIV, including individual standard deviation (iSD) and coefficient of variation (CoV), were derived for each participant. Ex-Gaussian (and Vincentile) analyses were used to characterize the RT distributions into three components: mu and sigma (mean and standard deviation of the Gaussian portion of the distribution) and tau (the ‘slow tail’ of the distribution). Results. Compared with healthy controls, iSD was increased significantly in all patient samples. Due to minimal changes in average RT, CoV was only increased significantly in BD depressed patients. Ex-Gaussian modelling indicated a significant increase in tau in euthymic BD [Cohen’s d = 0.39, 95% confidence interval (CI) 0.09–0.69, p = 0.011], and both sigma (d = 0.57, 95% CI 0.07–1.05, p = 0.025) and tau (d = 1.14, 95% CI 0.60–1.64, p < 0.0001) in depressed BD. The mu parameter did not differ from controls. Conclusions. Increased cognitive variability may be a core feature of mood disorders. This is the first demonstration of differences in attentional RT distribution parameters between MDD and BD, and BD depression and euthymia. These data highlight the utility of applying measures of IIV to characterize neurocognitive variability and the great potential for future application


Publication metadata

Author(s): Gallagher P, Nilsson J, Finkelmeyer AE, Goshawk M, Macritchie KA, Lloyd AJ, Thompson JM, Porter RJ, Young AH, Ferrier IN, McAllister-Williams RH, Watson S

Publication type: Article

Publication status: Published

Journal: Psychological Medicine

Year: 2015

Volume: 45

Issue: 14

Pages: 2985-2997

Print publication date: 01/10/2015

Online publication date: 15/06/2015

Acceptance date: 23/04/2015

ISSN (print): 0033-2917

ISSN (electronic): 1469-8978

Publisher: Cambridge University Press

URL: http://dx.doi.org/10.1017/S0033291715000926

DOI: 10.1017/S0033291715000926


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