NEW YORK -- Healthy older adults and those with mild cognitive impairment given a drug that spurs hormones important to normal brain function had improved concentration, decision-making skills and verbal memory, a study found.
The healthy adults given Egrifta, a drug that spurs the release of human growth hormone, had executive function improvements that were more than 100 percent greater than those in a placebo group, while verbal memory improvements were 50 percent greater, said Laura Baker, lead author of the study in the Archives of Neurology.
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The growth hormone is released from the brain and stimulates others that are important for normal brain function, Baker said. The system of hormones decline as people age. The findings offer a possible new treatment for the aging brain of healthy older adults as well as those with mild cognitive impairment, who are at an increased risk of developing Alzheimer's disease, she said.
"Very few other strategies to improve cognition in these adults have demonstrated success," Baker, an associate professor of psychiatry and behavioral sciences at the University of Washington School of Medicine in Seattle, said in an email. "This strategy of supplementing one hormone that can then impact several other hormones represents a new approach that targets an entire biological system to restore function to that of a younger adult."
More studies are needed to look at the safety and efficacy of long-term use on cognitive function in older adults before doctors can start prescribing it as a treatment, she said.
About 5.4 million Americans have Alzheimer's, the most common type of dementia, and by 2050 that number is expected to grow to as many as 16 million, according to the Alzheimer's Association. The number of people worldwide with the condition is expected to swell to 115 million by 2050.
Egrifta is used to reduce excess abdominal fat in HIV patients.
The drug mirrors a hormone that also is important in regulating the amount of insulinlike growth factor, IGF-1, which is released from the liver and crosses into the brain, Baker said. In humans, increased IGF-1 in the blood is associated with better performance on cognitive tests. Lower levels of the growth factor have been reported in patients with dementia, she said.
Researchers in the study included 137 adults, 61 with mild cognitive impairment, with an average age of 68. Patients either injected themselves with Egrifta or a placebo 30 minutes before going to sleep for 20 weeks.
They found that 20 weeks of taking the drug increased IGF-1 levels in the blood to that of a young adult and had a positive effect on executive function and short-term verbal memory for healthy older adults and those with mild cognitive impairment. Short-term visual memory didn't improve with the treatment, the authors said.
For those with mild cognitive impairment whose cognition is expected to worsen over time, the brain abilities of those who took the growth hormone didn't drop as much as those in the placebo group, Baker said.
The results show that the treatment "has benefits in cognition not only for healthy older adults, but also for adults at increased risk for Alzheimer's dementia," she said.