Growth Hormone Boost May Not Slow Alzheimer's

Nov. 20 -- WEDNESDAY, Nov. 19 (HealthDay News) -- A compound that boosts growth hormone levels in Alzheimer's patients may not slow the disease, new research suggests.

The study, funded by drug giant Merck, was spurred by promising animal research that had suggested that the compound, called MK-677, might help curb Alzheimer's effect on the brain.

However, "the study suggests that targeting this hormone system may not be an effective approach at slowing the rate of Alzheimer's disease progression," said study author Dr. J.J. Sevigny, associate director of clinical neuroscience at Merck Research Laboratories in North Wales, Pa. His team reported its finding in the Nov. 18 issue of Neurology.

"In a similar vein, the study challenges a commonly held theory that hormones may attack beta-amyloid plaque in the brain," Sevigny added. "That was the premise of this research: that by giving this medication we'd be able to influence the beta-amyloid in the brain. And we didn't receive this result in this study."

Based on the findings, Merck has now stopped investigating MK-677 for use against Alzheimer's.

The study comes on the heels of another report on the drug, published earlier this month in the Annals of Internal Medicine.

In that study, researchers at the University of Virginia found the use of MK-677 spurred an increase in muscle mass in older recipients. It also improved their fat distribution and boosted appetite as it restored the body's production of growth hormone to youthful levels. The intervention did not demonstrate any specific benefit with respect to boosting overall muscle strength or activity function, however.

In the new study, conducted between 2003 and 2005, Sevigny's team tracked the cognitive health of 416 U.S. patients with mild to moderate Alzheimer's disease, aged 50 and above.

During the study, half the patients received 25-milligram tablets of MK-677, while the other half consumed a placebo.

The researchers found that MK-677 was well-tolerated and produced a desirable 60 percent-plus increase in the pituitary gland's production of insulin-like growth factor-1 (IGF-1) within just six weeks. This boost increased to nearly 73 percent by the end of one year.