Hormone Shots Aid Cognition in Older Adults
Daily shots of growth hormone-releasing hormone (GHRH) improved cognition in both healthy adults and those with mild cognitive impairment, researchers reported.
In a five-month randomized trial, the substance, given subcutaneously, was associated with a significant improvement in cognitive performance compared with placebo, according to Laura Baker, PhD, of the University of Washington School of Medicine in Seattle, and colleagues.
The benefit was driven by significantly better executive function and a trend toward better verbal memory, although visual memory was not changed, the group reported online in Archives of Neurology.
GHRH stimulates release of growth hormone from the pituitary, in a pulsatile fashion, which in turn causes the release of insulin-like growth factor 1 from the liver, the researchers noted.
All three “have potent effects on brain function, their levels decrease with advancing age, and they likely play a role in the pathogenesis of Alzheimer’s disease,” Baker and colleagues wrote.
Evidence suggests that elevating hormone levels in people at risk for cognitive impairment might prevent mental decline or improve function, they noted.
To test the idea, they enrolled 152 adults, ages 55 to 87, including 66 with mild cognitive impairment (MCI). They were randomly assigned to placebo or tesamorelin (Egrifta), a stabilized analog of human GHRH, self-administered daily by subcutaneous injection.
All told, 137 participants — 76 healthy volunteers and 61 people with MCI – completed the 20-week study.
The primary outcome was cognitive change measured by a battery of standard tests at baseline and weeks 10, 20, and 30 (following a 10-week washout period). The researchers also conducted blood tests at those intervals to measure circulating levels of the three hormones.
They found:
- GHRH increased insulin-like growth factor 1 levels by an average factor of 2.17, which was significant at– still within the normal physiological range.
- On an intent-to-treat analysis, including 151 of the 152 volunteers, those taking GHRH had an improvement in cognition overall that was significant at and was comparable among both healthy participants and those with MCI.
- Among the 137 who completed the study, the pattern was similar but more robust.
- Analysis showed that GHRH significantly improved executive function, appeared to improve verbal memory, but had no effect on visual memory
GHRH also reduced body fat by 7.4 percent and, among those with MCI, increased fasting insulin levels by 35 percent.
Adverse events were mostly mild but were more common among those getting GHRH — 68 percent versus 36 percent.
The authors cautioned that the generalizability of the study is limited by the small sample size.
“Larger and longer-duration treatment trials are needed,” they concluded, “to firmly establish the therapeutic potential of GHRH administration to promote brain health in normal aging and ‘pathological aging.'”