The Association of Pain and Depression in Preadolescent Girls: Moderation by Race and Pubertal Stage

Individual differences in pain and depression are robustly related in adults, with each condition being associated with the severity of, impairment from, and service use for the other condition (Bair, Robinson, Katon, & Kroenke, 2003). The co-occurrence of pain and depression is common, with high rates observed in both psychiatric (Munoz et al., 2005) and primary care settings (Lepine & Briley, 2004). There also are significant sex differences in the experience of pain and depression. Compared with males, females report more depression symptoms and more pain, both naturalistically (Haugland, Wold, Stevenson, Aaroe, & Woynarowska, 2001) and in response to a pain stimulus in a laboratory (Jackson, Lezzi, Chen, Ebnet, & Eglitis, 2005). Individuals who experience pain and depressive symptoms are high rate health care consumers who use more general medical services, but fewer mental health services than individuals with depression only (Bao, Strum, & Croghan, 2003). As such, the co-occurrence of pain and depression is an issue of considerable public health significance, especially for females. The etiology of the co-occurrence of pain and depression is not known. Individual differences in depression and pain experience may be causally related, may co-occur relatively independently, or may covary over time implying a possible subtype of depressive disorder. As the biological systems involved in both pain and mood regulation are becoming more clearly articulated, it appears that the neural circuitry involved in either the processing and/or regulation of pain and depression overlaps to some extent (Brannan et al., 2005; Eisenberger & Lieberman, 2004). If the systems accounting for differences in pain response do overlap, then as individual differences in depression symptoms emerge, so too should individual differences in pain response. Establishing the developmental timing of the association between depression and pain response is important for generating testable hypotheses about the mechanisms by which these two psychological processes are related. Thus far, however, there is only indirect evidence that pain and depressive symptoms are associated during childhood and adolescence. For example, Egger and colleagues (Egger, Costello, Erkanli, & Angold, 2004) reported that girls with depression were close to 13 times more likely to report musculoskeletal pains and four times more likely to report headaches than girls without depression. But there are other developmental clues about the timing of the co-occurrence of individual differences in response to pain and depression. Many individuals with depressive disorders experience the onset of depression during adolescence, which is when sex differences in depression emerge. Interestingly, there also are age-related changes in pain tolerance (Lu et al., 2005) and physical complaints (LeResche, Mancl, Drangsholt, Saunders, & Von Korff, 2005), with sex differences in physical complaints emerging during adolescence (Kolip, 1997; LeResche et al., 2005). Thus, pubertal development may play a role in the interface between pain and depression. To date, however, there have been no studies in which depression and pain response are assessed using independent methods and operational definitions. Measuring such differences using rigorous, reliable and valid measures would add significantly to efforts aimed at testing the hypothesis that high rates of co-occurrence of individual differences in pain response and depression emerge in childhood. Moreover, establishing whether pubertal stage moderates the association between pain response and depression would provide some basis for exploring the role of pubertal hormones in the development of individual differences in pain, depression, and their co-occurrence. We have previously reported that African-American girls have higher levels of depression symptoms than European-American girls (Keenan et al., in press), which is consistent with findings from several other studies. This suggests that there may be specific socio-cultural stressors for African Americans, such as living in a low-income environment, that increase the possibility of transitioning from vulnerability, to being symptomatic. Such stressors may impact a variety of biological systems, some of which may affect pain sensation and depression. In fact, African-American adults usually report higher pain ratings and demonstrate greater pain sensitivity in response to a pain stimulus than other racial groups (Campbell, Hughes, Girdler, Maixner, & Sherwood, 2004; Klatzkin, Mechlin, Bunevicius, & Girdler, 2007; Weisse, Foster, & Fisher, 2005). Whether such racial differences are due to differences in socio-cultural factors, such as living in a low-income environment is not known. Controlling for poverty would partially answer this question. Nor is it known whether higher pain ratings among African Americans can be explained by higher ratings of depression; the threshold and tolerance of pain may be lower only among those individuals with high levels of depression. In the present study, we begin to address these specific issues by testing whether pain response using a controlled pain stimulus is associated with concurrent and later depressive symptoms using a clinically meaningful assessment of DSM-IV depressive symptoms in a nonclinical sample of preadolescent girls. We hypothesize that depression and pain response at age 10 will be associated with depressive symptoms at age 10 and at age 11, with higher levels of depression being associated with a lower pain threshold and lower pain tolerance. We further hypothesize that pubertal stage of development and race will moderate the association between pain response and depression, with African-American girls and girls at more advanced stages of pubertal maturation showing a stronger association between pain response and depressive symptoms.