Effects of mirthful laughter on growth hormone, IGF-1 and substance P in patients with rheumatoid arthritis.

Objective Growth hormone (GH) plays an ancillary role in the regulation of immune function. GH has been shown to be associated with joint symptoms such as pain and swelling. On the other hand, mirthful laughter has favorable effects on the neuroendocrine-immune system. We evaluated the levels of serum GH, insulin-like growth factor-1 (IGF-1) in RA patients and evaluated the effect of mirthful laughter on GH and IGF-1. Methods We compared with the levels of serum GH, IGF-1 and substance P (SP) in patients with RA and healthy subjects (control group) before and after exposure to Rakugo, a traditional Japanese comical story that induces mirthful laughter. Results The basal level of serum GH in the RA group was significantly higher than in the control group. After experiencing mirthful laughter, the level of serum GH in the RA group significantly decreased, approaching that in the control group. The serum IGF-1 level was lower in the RA group than in the control group. There was no significant difference in the level of serum SP between the RA group and the control group. Conclusion The basal level of serum GH in the RA group was significantly higher than in the control group, and the level of serum GH significantly decreased after experiencing mirthful laughter. These results suggest that the homeostasis of GH in patients with RA is disturbed, and the increased serum GH levels in RA patients may be associated with their stress condition.