a1 Laboratory of Neuropsychology, The University of Hong Kong, Hong Kong
a2 Laboratory of Cognitive and Affective Neuroscience, The University of Hong Kong, Hong Kong
a3 Institute of Clinical Neuropsychology, MacLehose Medical Rehabilitation Centre and The University of Hong Kong, Hong Kong
a4 Queen Mary Hospital, The University of Hong Kong, Hong Kong
a5 Department of Medicine, The University of Hong Kong, Hong Kong
a6 Department of Social Work and Social Administration, The University of Hong Kong, Hong Kong
a7 The Hong Kong Jockey Club Centre for Suicide Research and Prevention, Faculty of Social Sciences, The University of Hong Kong, Hong Kong
a8 Department of Diagnostic Radiology, The University of Hong Kong, Queen Mary Hospital, Hong Kong
Background Patients with major depressive disorder are found to show selective attention biases towards mood-congruent information. Although previous studies have identified various structural changes in the brains of these patients, it remains unclear whether the structural abnormalities are associated with these attention biases. In this study, we used voxel-based morphometry (VBM) to explore the structural correlates of attention biases towards depression-related stimuli.
Method Seventeen female patients with major depressive disorder and 17 female healthy controls, matched on age and intelligence, underwent magnetic resonance imaging (MRI). They also performed positive-priming (PP) and negative-priming (NP) tasks involving neutral and negative words that assessed selective attention biases. The reaction time (RT) to a target word that had been attended to or ignored in a preceding trial was measured on the PP and NP tasks respectively. The structural differences between the two groups were correlated with the indexes of attention biases towards the negative words.
Results The enhanced facilitation of attention to stimuli in the PP task by the negative valence was only found in the depressed patients, not in the healthy controls. Such attention biases towards negative stimuli were found to be associated with reduced gray-matter concentration (GMC) in the right superior frontal gyrus, the right anterior cingulate gyrus and the right fusiform gyrus. No differential effect in inhibition of attention towards negative stimuli in the NP task was found between the depressed patients and the healthy controls.
Conclusions Specific structural abnormalities in depression are associated with their attention biases towards mood-congruent information.
(Received February 04 2008)
(Revised August 26 2008)
(Accepted August 30 2008)
(Online publication October 23 2008)