Trained dogs can detect the odor of Parkinson's disease.

Chronic musculoskeletal pain, most commonly low back and neck pain, is the primary cause of disability worldwide (). It accounts for a large proportion of chronic pain overall (). Chronic pain has been related to various unfavorable health outcomes such as anxiety, depressive disorder, activity limitation, and decreased quality of life (; ; ). Furthermore, healthcare treatment related to chronic pain and the loss of worker productivity due to pain have tremendously impacted the United States (). Consequently, chronic musculoskeletal pain impacts both individual lives and society as a whole. Previous studies have reported that an individual’s psychological characteristics, such as anxiety and depression, are associated with pain-related outcomes, including pain intensity, pain interference, disability, and physical function (; ). In particular, pain catastrophizing is considered to be a critical psychological factor associated with pain-related outcomes (; ). Pain catastrophizing is defined as the repetitive development of exaggerated and negative cognitive and emotional schemas characterized by rumination, magnification, and helplessness in response to actual or anticipated pain (; ). Pain catastrophizing has been found to act as a mediator between pain intensity and depression among adults with chronic noncancer pain (); between race and/or ethnicity and pain-related outcomes, such as pain intensity and disability in adults with knee osteoarthritis (); and between pain intensity and pain interference among patients enrolled in an interdisciplinary pain rehabilitation program (). A better understanding of the associations between pain catastrophizing and pain-related outcomes can facilitate a greater understanding of chronic musculoskeletal pain, which in turn can contribute to better clinical decision-making for the treatment of patients with chronic musculoskeletal pain. Two previous review studies have identified associations between pain catastrophizing and both pain-related outcomes and psychological conditions (; ). However, one review focused on comprehensive chronic pain, and the other review, although focused on musculoskeletal pain, was published 5 years ago and did not include randomized clinical trials (RCTs).