Low back pain (LBP) is a common musculoskeletal health problem in industrialized countries and one of the worst leading specific causes of years lived with disability. We conducted a cohort study specifically targeting Japanese workers. Results suggest that psychosocial factors such as low job satisfaction, little social support, depression, and somatization are important risk factors for aggravating LBP and are consistent with foreign studies despite cultural differences. Additionally, neck and shoulder discomfort ("katakori" in Japanese) is common among Japanese adults, especially females. Psychosocial stress is likely to trigger brain dysfunction, leading to depression and somatization. Our data suggests a new concept of LBP and "katakori" as a form of somatization, possibly derived from psychological stress.