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

Published online by Cambridge University Press:  15 June 2015

P. Gallagher ,
J. Nilsson ,
A. Finkelmeyer ,
M. Goshawk ,
K. A. Macritchie ,
A. J. Lloyd ,
J. M. Thompson ,
R. J. Porter ,
A. H. Young  and
I. N. Ferrier
...Show all authors
P. Gallagher*
Affiliation:
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
J. Nilsson
Affiliation:
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK Ageing Research Institute, Karolinska Institute, Solna, Sweden
A. Finkelmeyer
Affiliation:
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
M. Goshawk
Affiliation:
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
K. A. Macritchie
Affiliation:
South London and Maudsley NHS Foundation Trust, London, UK
A. J. Lloyd
Affiliation:
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK Northumberland, Tyne and Wear NHS Foundation Trust, UK
J. M. Thompson
Affiliation:
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
R. J. Porter
Affiliation:
Department of Psychological Medicine, University of Otago, Christchurch, New Zealand
A. H. Young
Affiliation:
King's College London, Institute of Psychiatry, Psychology and Neurosciences, London, UK
I. N. Ferrier
Affiliation:
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
R. H. McAllister-Williams
Affiliation:
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK Northumberland, Tyne and Wear NHS Foundation Trust, UK
S. Watson
Affiliation:
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK Northumberland, Tyne and Wear NHS Foundation Trust, UK
*
* Address for correspondence: P. Gallagher, Institute of Neuroscience, Newcastle University, The Henry Wellcome Building, Framlington Place, Newcastle upon Tyne NE2 4HH, UK. (Email: [email protected])
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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.

Keywords

Attentionbipolar disorderex-Gaussian analysesmajor depressionneuropsychologyvariability
Type
Original Articles
Information
Psychological Medicine , Volume 45 , Issue 14 , October 2015 , pp. 2985 - 2997
Copyright
Copyright © Cambridge University Press 2015 

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