Researchers split 20 high-risk diabetic patients —all with hypertension and hyperlipidemia (a risk factor for cardiovascular disease)— into two groups. Both groups were given standard diabetes medication. Group L viewed 30 minutes of humor of their choosing, while Group C, the control group, did not. This went on for a year of treatments.
By two months into the study, the patients in the laughter group (Group L) had lower levels of the hormones epinephrine and norepinephrine, both considered to be measures of stress. Stress is known to be deadly.
After the 12 months, HDL cholesterol (the good kind) had risen 26 percent in Group L but only 3 percent in the Group C. In another measure, C-reactive proteins, a marker of inflammation and cardiovascular disease, decreased 66 percent in the laughter group but only 26 percent in the control group.
"The best clinicians understand that there is an intrinsic physiological intervention brought about by positive emotions such as mirthful laughter, optimism and hope," said study leader Lee Berk of Loma Linda University. And other research has found that humor makes us more hopeful.
Still, more study is needed to determine what these results mean, Berk said.
Previous research by Berk and colleagues found that the mere anticipation of humor can bring about similar changes in body chemistry found in the new study, which will be presented this month at the annual meeting of the American Physiological Society.
Research in 2005 at the University of Maryland School of Medicine indicated that laughter causes the inner lining of blood vessels to dilate or expand, increasing blood flow in a manner thought to be healthy.
"Lifestyle choices have a significant impact on health and disease and these are choices which we and the patient exercise control relative to prevention and treatment," Berk said in a statement this week.