Design and Implementation of an fMRI Study Examining Thought Suppression in Young Women with, and At-risk, for Depression

Summary

We aim to identify the neural correlates underlying sustained and transient thought suppression, and thought re-emergence in controls, at-risk and depressed individuals. Activation was greatest for controls compared to the at-risk and the depressed group in the dorsolateral prefrontal cortex during thought suppression and anterior cingulate cortex during thought re-emergence.

Abstract

Ruminative brooding is associated with increased vulnerability to major depression. Individuals who regularly ruminate will often try to reduce the frequency of their negative thoughts by actively suppressing them. We aim to identify the neural correlates underlying thought suppression in at-risk and depressed individuals. Three groups of women were studied; a major depressive disorder group, an at-risk group (having a first degree relative with depression) and controls. Participants performed a mixed block-event fMRI paradigm involving thought suppression, free thought and motor control periods. Participants identified the re-emergence of “to-be-suppressed” thoughts (“popping” back into conscious awareness) with a button press. During thought suppression the control group showed the greatest activation of the dorsolateral prefrontal cortex, followed by the at-risk, then depressed group. During the re-emergence of intrusive thoughts compared to successful re-suppression of those thoughts, the control group showed the greatest activation of the anterior cingulate cortices, followed by the at-risk, then depressed group. At-risk participants displayed anomalies in the neural regulation of thought suppression resembling the dysregulation found in depressed individuals. The predictive value of these changes in the onset of depression remains to be determined.

Introduction

A common trait in individuals with major depressive disorder (MDD) is the tendency to engage in ruminative thought¹. This coping mechanism is considered maladaptive as it involves passive fixation on negative thoughts and events with no attempt at resolution^2-5. Rumination is associated with increased risk of developing depression^1,6-9 and increased length and severity of depressive episodes¹⁰.

Individuals who regularly ruminate will often try to reduce the frequency of these negative thoughts by actively suppressing them¹¹. However, engaging in thought suppression can make such thought....

Protocol

All participants were briefed about the procedures and signed a consent form prior to study initiation. The McMaster University Health Sciences and St. Joseph’s Healthcare Research Ethics Boards approved all procedures.
Note: In this protocol, 47 right-handed females between the ages of 16 and 24 years are used. Of which, 15 participants suffer from MDD (physician-confirmed diagnosis) and are experiencing a depressive episode at the time of the study. This group of individuals is denoted as the “MDD group”. The at-risk group in this protocol consists of 16 participants who have a first degree relative (parent or sibling) with a diagnosis of MDD....

Results

Block Condition Analyses: Thought Suppression versus Motor Control

ANOVA analyses were used to determine the brain activation associated with block periods of thought suppression (with intrusions removed) relative to a motor control. Contrast results for control and at-risk versus MDD, control versus MDD, control versus at-risk, and at-risk versus MDD are detailed in Table 1. There were no between or within group differences in activity associated with suppression of personally r.......

Discussion

Elements of the neural circuitry disrupted in depression^15,16,25 are also associated with the regulation of conscious thought^17,18. By examining suppression-related neural processing in at-risk and depressed participants we were able to examine whether there are alterations in brain activation patterns that are common in both individuals with a genetic predisposition to depression and a current depressive episode.

In keeping with our hypotheses and the existing literature.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Magnetic Resonance Imaging Scanner	General Electric		3T, whole body, short bore scanner, Milwaukee, WI
Brain Voyageur, QX, V2.1	Brain Innovation (B.V.)		Maastricht, The Netherlands
E-prime	Psychology Software Tools		Pennsylvania, USA
Hamilton Depression Rating Scale (HAM-D)	Hamilton M (1967) Development of a rating scale for primary depressive illness. The British journal of social and clinical psychology 6: 278–296
Rosenberg Self-Esteem Questionnaire (RSE)	Rosenberg M (1965). Society and the Adolescent Self-Image. Princeton University Press : Princeton, NJ.
Childhood Trauma Questionnaire (CTQ)	Bernstein DP, Stein JA, Newcomb M, et al. (2003) Development and validation of a brief screening version of the Childhood Trauma Questionnaire. Child Abuse & Neglect 27: 169–190.
Mini International Neuropsychiatric Inventory (MINI)	Folstein, M. F., Folstein, S. E., & McHugh, P. R. (1975). “Mini-mental state.” Journal of Psychiatric Research, 12(3), 189–198.
Beck Depression Inventory-Version II (BDI-II)	Beck AT, Ward CH, Mendelson M, Mock J, Erbaugh J (1961) An inventory for measuring depression Archives of General Psychiatry 4:561 - 571