Although patients with a depressive disorder report often of pain, their sensitivity to experimental pain is controversial, probably due to differences in sensory testing methods and to the lack of normal values. Therefore, we used a standardized and validated comprehensive sensory testing paradigm to assess the peripheral and central nervous system performance in depressive patients compared to healthy controls and chronic pain patients with fibromyalgia syndrome (FMS), in which depression is a common comorbidity. Twenty-five depressive psychiatric inpatients (pain-free: n = 20), 35 FMS outpatients and 25 healthy controls underwent quantitative sensory testing (QST), including thermal and mechanical detection and pain thresholds, pain sensitivity and responsiveness to repetitive noxious mechanical stimuli (wind-up). In depressive disorder (to a lesser extent also in FMS), significantly decreased cold pain thresholds and an increased wind-up were found, although the mechanical pain thresholds and pain sensitivity were comparable to those of the healthy controls. All the detection thresholds were within the normal range in all the groups. In depressive disorder, there were no significant side differences in the detection and pain thresholds.
The results contradict the former assumption of a general insensitivity to experimental pain in depressive disorder. In the mostly pain-free patients signs of an enhanced central hyperexcitability are even more pronounced than usually found in chronic pain patients (e.g. FMS), indicating common mechanisms in depressive disorder and chronic pain in accordance with the assumption of non-pain associated mechanisms in depressive disorder for central hyperexcitability, e.g. by inhibited serotonergic function. Furthermore, this trial demonstrates the feasibility of QST in depressive patients.
aDepartment of Pain Management, Berufsgenossenschaftliche Universitätsklinik Bergmannsheil GmbH, Ruhr University Bochum, Bürkle-de-la-Camp-Platz 1, 44789 Bochum, Germany
bDepartment of Psychiatry, Ruhr University Bochum, LWL University Hospital, Alexandrinenstrasse 1, 44791 Bochum, Germany
cPrivate Practice of Rheumatology, Richard-Wagner-Strasse 13–17, 50674 Cologne, Germany
dDivision of Neurophysiology, CBTM, Medical Faculty Mannheim, Ruprecht Karls University Heidelberg, Ludolf-Krehl-Strasse 13–17, 68167 Mannheim, Germany
*Corresponding author. Tel.: +49 234 3026366; fax: +49 234 3026367.
1These authors contributed equally to this study.
2This work is part of the Doctoral Thesis of Sabrina Klauenberg.
Submitted May 24, 2008; revised August 10, 2008; accepted September 3, 2008.