Executive function and verbal memory improved in patients with mild cognitive impairment (MCI) and healthy controls after 20 weeks of treatment with growth hormone–releasing hormone (GHRH), according to research published in the August 6 online Archives of Neurology.
Cognitive performance differed between controls and patients with MCI, but the positive effect of GHRH was comparable in both populations. Univariate analyses of constituent composites scores suggested that GHRH resulted in cognitive improvement in controls and reduced decline in patients with MCI.
Laura D. Baker, PhD, Assistant Professor of Psychiatry and Behavioral Sciences at the University of Washington in Seattle, and colleagues enrolled 152 adults in a randomized, double-blind trial to study the effects of GHRH on cognitive function. Participants’ mean age was 68, and 66 patients had MCI. Patients gave themselves a subcutaneous injection containing either 1 mg of tesamorelin, a stabilized analog of human GHRH, or placebo every day for 20 weeks.
The investigators collected blood samples and administered cognitive tests at baseline, at weeks 10 and 20, and after a 10-week washout. Patients underwent an oral glucose tolerance test and a dual-energy x-ray absorptiometry scan before and after week 20 to measure body composition. Primary outcome measures were executive function, verbal memory, and visual memory.
“GHRH-stimulated increases in circulating insulin may help to override the early negative effects of [Alzheimer’s disease] pathology to boost performance on abilities (such as declarative memory) that are particularly sensitive to insulin-related dysfunction,” said Dr. Baker. “Our results replicate and expand our earlier positive findings, demonstrating that GHRH administration has favorable effects on cognitive function, not only in healthy older adults, but also in adults at increased risk of cognitive decline and dementia. Larger and longer-duration treatment trials are needed to firmly establish the therapeutic potential of GHRH administration to promote brain health in normal aging and ‘pathological aging,’” she concluded.
Baker LD, Barsness SM, Borson S, et al. Effects of growth hormone–releasing hormone on cognitive function in adults with mild cognitive impairment and healthy older adults. Arch Neurol. 2012 Aug 6 [Epub ahead of print].