Pain
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Depression is a common feature of chronic pain, but there is limited research into the content and frequency of depressed cognitions in pain patients. A limitation of previous research is the failure to include nonpain depressed comparison groups. The present study used a sentence completion task to investigate the content of cognition in 4 groups of participants: with pain and concurrent depression, pain without depression, depression without pain, and with neither pain nor depression. ⋯ The strengths of the current study are the inclusion of the depressed nonpain group, the use of a comprehensive coding scheme applied by 2 independent raters, and the presence of depression validated through a diagnostic interview. In contrast to depressed groups without pain, participants with pain and depression exhibit a cognitive bias specific to negative aspect of health. This focus facilitates understanding of the relationship between depression and pain processing: The implications for therapeutic interventions are discussed.
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Many acute stressors reduce pain, a phenomenon called stress-induced antinociception (SIA). Stress also is associated with increased scratching in chronic itch conditions. We investigated effects of acute stressors on facial itch and pain using a recently introduced rat model. ⋯ W-SIA tended to equalize scratching and swiping elicited by 5-HT and AITC compared with no-swim controls, suggesting altered itch and pain processing. Exercise (wheel-running), novelty, cold exposure, and fear (shaker table), key components of swim stress, differentially affected tail-flick latencies and 5-HT-evoked swiping and scratching behavior. Thus, itch and pain can be simultaneously suppressed by a combination of acute stress-related factors via an opioid-independent mechanism.