A drug that's already been approved by the FDA for use in HIV patients may also help slow the decline of memory and mental function experienced by people who are in the early stages of Alzheimer's disease.

The drug, Egrifta, stimulates the release of human growth hormone from the brain's pituitary gland. It was approved by the FDA in 2010 to help correct the abnormal distribution of body fat that often occurs in patients who live with HIV.

A new study published in the Archives of Neurology suggests it may also slow memory loss in people who have mild cognitive impairment (MCI), a condition that often precedes full-blown Alzheimer's disease.

For the study, researchers assigned adults between the ages of 55 and 87 to get either nightly injections of Egrifta or a placebo for five months. Some were healthy and showed no evidence of memory problems on a battery of mental function tests. Others showed MCI, or memory loss that was worse than expected for their age but was not yet severe enough to interfere with daily living.

A total of 137 patients -- 76 who were healthy and 61 with MCI -- finished the study. Researchers brought them back to the lab four times: at the start of the study, then at weeks 10, 20, and then another 10 weeks after the nightly shots stopped.

At each visit, their blood was drawn. In addition, they took a battery of tests that measured different skills used in mental processing and short-term recall of words, shapes, and facts. Researchers also asked them about their mood and sleeping patterns.

In both healthy adults and those with MCI, those taking Egrifta fared better than their counterparts who took placebo injections.

Healthy adults saw their executive function improve by about 200% over their peers who got a placebo. Executive function refers to the brain's ability to manage attention and concentration, to switch between thoughts, and use working memory to plan and strategize tasks.

Adults with MCI still saw their executive function slip over the five months of the study, but their declines were not as large as those in the placebo group.

"Their expected decline was cut in half," says researcher Laura D. Baker, PhD, a psychiatrist at the University of Washington School of Medicine in Seattle.

By the end of the study, people on the drug were also better able to recall words and details of stories a bit better than people on the placebo, though the differences between the groups were not significant.
How Egrifta Works

Egrifta is a close copy of a chemical that's already made by the body called growth-hormone-releasing hormone. As the name implies, it stimulates the production of human growth hormone (HGH). Human growth hormone, in turn, triggers the release of a whole cascade of other hormones including insulin and its close cousin, insulin-like growth factor.

Insulin is probably best known for its role in regulating blood sugar, but it also has important work in the brain. In the brain, insulin stimulates the growth of new nerves and protects existing nerves from damage. Insulin levels in the brain fall with age, and previous studies have found that they're especially low in the brains of patients with Alzheimer's and other kinds of dementia.

The same group of researchers involved in the study has been testing whether inhaled insulin can reverse memory loss in Alzheimer's patients.

Egrifta may boost insulin in the brain less directly, and that could be a good thing, Baker says.

"What's so nice about this particular strategy is that it stimulates a whole cascade of hormone activities. Once this whole cascade is stimulated, it behaves normally, as it does when we're younger adults. So all we're kind of doing is boosting the system and letting it do what it does best," she says.

"It also shuts itself off when levels of one hormone or another get too high," Baker tells WebMD, so the levels always stay within a more normal range.
Risk, Side Effects, and Cost to Be Considered

Should a larger, longer study confirm the benefits of the medication for patients with early memory loss, it wouldn't come cheap.

Baker says that given at the dosages used in the study, the drug costs about $750 a day, or more than $22,500 for a 30-day supply.

"Of course that's not feasible," she says. "No health plan would ever pay for this."

She says drug companies are hard at work trying to find a way to make a less expensive version.

Side effects were reported by 68% of people on Egrifta -- twice the rate of adverse events experienced by those on the placebo injections. Side effects were mostly mild. They included skin reactions like itching, redness, and stinging around the injection site. It was also common for people to report increased joint pain and stomach upset.

There are already products at vitamin and health foods stores that claim to boost growth-hormone-releasing hormone, but Baker cautions that they could do so dangerously.

But, she says, there is a far less expensive and less risky way to get virtually the same degree of benefit as was seen with this pricey drug: Exercise.

"We completed a study last year testing exercise for brain function in people with mild cognitive impairment," Baker says. "We had the same improvements in executive function. We used the same tests in both studies, and we saw the same benefits."

How much exercise is needed to get the benefit? In her previous study, which was published in 2010 in the Archives of Neurology, people engaged in aerobic exercise for 45 to 60 minutes at least four days of the week for six months.

"Up to this point, this is the most potent way to slow things down or improve cognition," she says.