Hormone injections may improve concentration, decision-making skills and verbal memory in healthy older adults and those with mild cognitive impairment, according to a new study.

Researchers found that Theratechnologies Inc.’s Egrifta, a drug already approved by federal regulators and triggers the release of human growth hormone from the brain's pituitary gland, improved executive function in healthy adults by more than 100 percent and verbal memory by 50 percent more than the placebo in a five-month randomized trial.

The study, published in online in Archives of Neurology, found that while participants given daily shots of the growth hormone-releasing hormone showed significant improvement in executive function and verbal memory, there was no evidence that the drug improved visual memory.

Researchers explain that the growth hormone GHRH that is released from the brain stimulates other hormones that are essential for normal brain function, and because hormones decline as people age, may offer a possible new treatment in preserving brain function in healthy older adults and those with mild cognitive impairment, who are at a greater risk of developing Alzheimer's disease.

"Growth hormone-releasing hormone (GHRH), growth hormone and insulin-like growth factor 1 have potent effects on brain function, their levels decrease with advancing age, and they likely play a role in the pathogenesis of Alzheimer disease," study author Laura D. Baker of the University of Washington's School of Medicine and her colleagues wrote.

Previously, Baker found that GHRH provided a short-term improvement in memory and concentration for healthy adults, which led her to assess in the current study whether the hormone could help restore some function in people who were already showing signs of mild cognitive impairment, a condition in which sufferers have problems with memory and focus and are at an increased risk for neurodegenerative disorders.

The latest study included 137 adults, including 61 with mild cognitive impairment. Participants were randomly assigned to receive a daily self-administered injection of either growth hormone-releasing hormone or a placebo injection for 20 weeks.

Participants took cognitive tests at the start of the study and at 10, 20 and 30 weeks after treatment began.

Researchers noted that GHRH treatment also increased insulin-like growth factor 1 levels by 117 percent and increased fasting insulin levels within the normal range by 35 percent in participants with mild cognitive impairment but not in healthy adults.

"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," the authors concluded. "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.'"