SAN DIEGO -- Stimulating the production of growth hormone in healthy older men and women can return hormone levels to those found in younger adults and reduce body fat, according to research being conducted at the University of Washington and the Veterans Affairs Puget Sound Health Care System in Seattle. Preliminary results of the study are presented June 12 in San Diego at the annual meeting of the Endocrine Society.
Principal investigator Dr. Michael Vitiello of the UW Department of Psychiatry and Behavioral Sciences, along with Drs. George Merriam and Robert Schwartz of the UW Department of Medicine and the VA, are studying the use of GH-releasing hormone (GHRH), a growth hormone stimulator, to increase production of growth hormone in 60 healthy men and women over age 65. GHRH is normally produced in the brain by the hypothalamus and stimulates production of growth hormone by the pituitary.
Although growth hormone is known best for promoting growth in childhood, it has important actions in adults. It regulates body fat, increases muscle mass and capacity for aerobic exercise, and may support normal mood and cognition. Some effects are carried out by stimulating increased production of insulin-like growth factor-I (IGF-I) in the liver and other tissues.
Secretion of growth hormone decreases with age, and many changes of aging resemble abnormalities seen in younger people with growth hormone deficiency: reduced strength and energy, increased body fat (especially around the abdomen) and psychological changes. Some studies suggest that age-associated changes in sleep and cognition may also be related to this decline in growth hormone.
Loss of muscle mass and strength are major problems for the elderly, leading to more falls and increased difficulty coping with tasks of independent daily living. Hormones or other agents that promote muscle strength and energy could help seniors remain independent longer.