Increased Prefrontal Activation During Pain Perception in Major Depression
Received 18 December 2006; received in revised form 30 January 2007; accepted 12 February 2007. published online 14 June 2007.
Background
To further elucidate the close interrelation of pain and depression, we investigated cerebral responses to parametrically varied thermal pain intensities in female patients suffering from major depressive disorder (MDD) (n = 13) and matched control subjects (n = 13) by means of functional magnetic resonance imaging (fMRI).
Methods
After the assessment of the individual thermal pain threshold, an fMRI-compatible thermode was used to deliver thermal painful stimuli to the right arm. All stimuli were initiated for 10 sec from a baseline resting temperature (32°C) in three different conditions (37°C, 42°C, 45°C). Statistical Parametric Mapping 2 (SPM2) software was used for image processing and statistical analyses.
Results
Patients displayed significantly increased thermal pain thresholds. A comparable increase in blood oxygenation level-dependent (BOLD) signal was observed in key structures of the pain matrix in patients and control subjects. Patients displayed hyperactivation in comparison with control subjects for the painful 45°C condition in the left ventrolateral thalamus, in the right ventrolateral prefrontal cortex (VLPFC) and dorsolateral prefrontal cortex (DLPFC), as well as a stronger parametric BOLD signal increase in the right VLPFC, DLPFC, and in the contralateral insula. Symptom severity correlated positively with the BOLD signal in the left ventrolateral nucleus of the thalamus.
Conclusions
We present evidence that cortical structures of the pain matrix are similarly activated in depressed patients and healthy subjects. We report increased prefrontal and lateral thalamic activation during the presentation of painful stimuli, which might explain reduced thermal pain perception on the skin in depressed patients.
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