Previous studies have shown a positive association between
pain and depression, though evidence supporting a direct link between these two variables is less robust. Using a placebo-controlled trial, the authors examined the
analgesic and
antidepressant efficacy of
paroxetine (20 mg) in chronic
low back pain sufferers. The authors examined the associations among
pain, depression, disability, and illness attitudes.
Paroxetine showed no effects on
pain or depression compared with placebo; however, subjects randomized to
paroxetine were more likely to reduce concomitant
analgesic medication. The cross-sectional association of depression and
pain at baseline (r = 0.2, P = 0.02) was weaker than the association between depression and disability (r = 0.3, P = 0.004). Similarly, the association of change in depression scores with change in
pain (r = 0.25, P = 0.016) was weaker than change between depression and disability (r = 0.49, P<0.0005). Whereas the relationship between
pain and depression became nonsignificant when disability and illness attitudes were controlled, the relationship between depression and disability remained highly significant when
pain and illness attitudes were controlled. These data are consistent with the association between
pain and depression being wholly modulated by disability and illness attitudes, with no direct relationship between
pain and depression.