Cognitive Labs

Insulin growth factor 1

Sometimes research leads to unexpected results. For example, stimulating growth hormone secretion in Alzheimer's patients did not help clear protein-containing beta-amyloid plaques or halt disease progression, as was hypothesized, particularly in APOEe4 carriers. Researchers used an experimental growth hormone secretion booster known as MK-677.

While the growth hormone dramatically increased levels of insulin-like growth factor-1 (IGF-1), which in animal studies had been shown to increase clearance of beta-amyloid, there was no incipient trend of beta-amyloid clearance in a subgroup of patients.

"Given that multiple pathways contribute to the clinical Alzheimer's disease phenotype," the scientists wrote, "it is possible that selectively altering the IGF-1 system alone is insufficient to slow the overall rate of disease progression."

563 patients age 50 or older were analyzed at 45 sites. Participants were randomized to double-blind treatment with the growth hormone-stimulating agent MK-677 at a dose of 25 mg or placebo for 12 months.

Growth hormone secretagogue therapy had the expected effect on serum IGF-1 levels -- a 60.1% increase at six weeks and a 72.9% increase at 12 months -- that were significantly greater than in the placebo group (difference 61.4 ng/mL at 12 months, P<0.001).

But the researchers noted that the effect was small and substantially less than reported for FDA-approved cholinesterase inhibitors.

The only subgroup that appeared to potentially benefit from growth hormone treatment were noncarriers of the apolipoprotein E (APOE) epsilon (e) 4 allele gene, that is, individuals with APOE2 or APOE3 biomarkers. (the link provides a general overview of APOE)

This group had a marginally significant improvement in global clinical status measured by CIBIC-plus (P≤0.05) and some numerical but nonsignificant effects on the other efficacy outcomes.

The researchers noted that this was not a prespecified subgroup analysis and should be interpreted with caution.

Source reference:

Sevigny JJ, et al "Growth hormone secretagogue MK-677: No clinical effect on AD progression in a randomized trial" Neurology 2008; 71:1702-1708.

Note: The research was funded by Merck and the authors have been financially supported by, and/or own stock-options of Merck, Inc.

Labels: apoe, hgh, igf1, merck, mk677

A new study in Seattle has examined the effectiveness of Human Growth Hormone as an aid to sleep. HGH drops sgnificantly in the 30's and 40's as part of the aging process. Scientists speculate that the decline in HGH is one of the factors causing insomnia and poor quality of sleep often observed as individuals age.

HGH, responsible for growth spurts in children, was administered to a group of subjects at the University of Washington's Sleep Research Group. Recipients of the substance scored 5-7% higher in tests of cognitive function than individuals in the control group, while also experiencing longer, more restful sleep.

Labels: hgh, human_growth_hormone, memory-test, rest, sleep