Effects of stressor controllability on psychophysiological, cognitive and behavioural responses in patients with major depression and dysthymia.
BACKGROUND
The experience of uncontrollability and helplessness in the face of stressful life events is regarded as an important determinant in the development and maintenance of depression. The inability to successfully deal with stressors might be linked to dysfunctional prefrontal functioning. We assessed cognitive, behavioural and physiological effects of stressor uncontrollability in depressed and healthy individuals. In addition, relationships between altered cortical processing and cognitive vulnerability traits of depression were analysed.


METHODS
A total of 26 unmedicated depressed patients and 24 matched healthy controls were tested in an expanded forewarned reaction (S1-S2) paradigm. In a factorial design, stressor controllability varied across three consecutive conditions: (a) control, (b) loss of control and (c) restitution of control. Throughout the experiment, error rates, ratings of controllability, arousal, emotional valence and helplessness were assessed together with the post-imperative negative variation (PINV) of the electroencephalogram.


RESULTS
Depressed participants showed an enhanced frontal PINV as an electrophysiological index of altered information processing during both loss of control and restitution of control. They also felt more helpless than controls. Furthermore, frontal PINV magnitudes were associated with habitual rumination in the depressed subsample.


CONCLUSIONS
These findings indicate that depressed patients are more susceptible to stressor uncontrollability than healthy subjects. Moreover, the experience of uncontrollability seems to bias subsequent information processing in a situation where control is objectively re-established. Alterations in prefrontal functioning appear to contribute to this vulnerability and are also linked to trait markers of depression.
Diener
C
C
Department of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, University of Heidelberg, Mannheim, Germany. carsten.diener@zi-mannheim.de
Kuehner
C
C
Brusniak
W
W
Struve
M
M
Flor
H
H
D000328:Adult; D000704:Analysis of Variance; D001008:Anxiety Disorders / Q000523:psychology; D001519:Behavior; D003071:Cognition; D015897:Comorbidity; D003865:Major Depressive Disorder / Q000150:complications / Q000523:psychology*; D019263:Dysthymic Disorder / Q000150:complications / Q000523:psychology*; D004569:Electroencephalography / Q000379:methods; D004644:Emotions; D005260:Female; D006380:Helplessness, Learned; D006801:Humans; D007389:Internal-External Control; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D011603:Psychophysiology; D011930:Reaction Time; D017678:Sex Distribution; D012919:Social Behavior; D013315:Stress, Psychological / Q000150:complications / Q000523:psychology*; D055815:Young Adult