Growth hormone secretagogue does not slow progression of Alzheimer's

A trial of the experimental growth hormone secretagogue MK-667 to determine whether it could help to slow the progression of Alzheimer's disease has produced disappointing results.

Studies on mice have suggested that the hormone insulin-like growth factor-1 (IGF-1) may help to reduce levels of beta-amyloid, the main constituent of the amyloid plaques that are seen in the brains of people with Alzheimer's disease. As growth hormone stimulates the release of IGF-1, researchers had hoped that MK-667, which stimulates the release of growth hormone from the pituitary gland, may help to slow the progression of the neurodegenerative disease.

Researchers studied 416 people who had mild to moderate Alzheimer's disease for one year. Half of participants took MK-677, whilst the other half took a placebo. Results showed that MK-677 was effective at increasing IGF-1 levels; however it was not effective at slowing the progression of Alzheimer's disease.

“This work suggests that targeting this hormone system may not be an effective approach to slowing the rate of Alzheimer's disease progression,” says study author J.J. Sevigny, MD, in a news release. “Importantly it challenges the common theory that hormones may attack beta-amyloid plaque in the brain and builds on the body of clinical evidence for Alzheimer's disease as we seek to develop more effective treatments.”
 
Sevigny JJ, Ryan JM, van Dyck CH, Peng Y, Lines CR, Nessly ML. On behalf of the MK-677 Protocol 30 Study Group. Growth hormone secretagogue MK-677: No clinical effect on AD progression in a randomized trial. Neurology 2008;71:1702-1708.

News release: Does Growth Hormone Drug Slow Alzheimer's Disease? American Academy of Neurology. November 17th 2008.