Recent research findings put a spotlight on the link between human growth hormone (HGH) and Alzheimer’s disease. Could taking HGH increase your risk of Alzheimer’s?
Ultimately, scientists say they have no cause for concern about HGH’s impact on Alzheimer’s risk. But data from a 2024 study is important to understand and take seriously. Here’s a closer look at the science.
What Data Shows That HGH Increases Alzheimer’s Risk?
In January 2024, researchers in the U.K. published a study in the journal Nature Medicine proposing that several people who received cadaveric growth hormone between 1959 and 1989 as a treatment for growth deficiencies later developed Alzheimer’s as a result of that treatment.
History of HGH
HGH is a naturally occurring hormone in your body. Cadaveric growth hormone is also called pituitary-derived hormone. This HGH came from the pituitary glands of people who’d died. Doctors stopped using this type of growth hormone as a treatment in the late 1980s. These days, HGH treatments are synthetic (lab-made).
Doctors prescribe synthetic HGH shots as a treatment for:
- Growth hormone deficiency
- Conditions that cause short stature, such as chronic kidney disease, Turner syndrome, and Prader-Willi syndrome
- Muscle tissue loss tissue from HIV
- Short bowel syndrome
Back in 1985, someone taking pituitary-derived growth hormone developed a fatal brain disease that causes dementia called Creutzfeldt-Jakob disease (CJD). Researchers suspected there may be a link between pituitary-derived growth hormone shots and the case of CJD.
Later cases of CJD in people taking pituitary-derived growth hormone confirmed it was the cause. Doctors stopped the use of HGH from cadavers as a result and have continued to closely follow anyone who received the treatment.
HGH and Alzheimer’s
In 2015, a research team in the U.K. autopsied four people who took pituitary-derived growth hormone treatment, and later died of CJD, and discovered that the blood vessels in their brains were full of beta amyloid. Beta amyloid is a protein that builds up in your brain when you have Alzheimer’s disease.
The research team tested eight of the 1,800 people still living who received growth hormone from deceased donors in the U.K. Five of them met the criteria for an Alzheimer’s diagnosis. Of these five, most had very early-onset Alzheimer’s, with symptoms starting in their late 30s and 40s. One of the other three had a slight decline in mental skills (mild cognitive impairment, or MCI), and a seventh person with no cognitive impairment showed beta amyloid buildup in the fluid around their spine.
These findings raised the possibility that some who took pituitary-derived growth hormone during that 30-year period who didn’t die from CJD may eventually develop Alzheimer’s disease.
But what it tells scientists about Alzheimer’s disease beyond this isn’t very clear, says Pinchas Cohen, MD, a distinguished professor of gerontology, medicine, and biological sciences and dean of the USC Leonard Davis School of Gerontology.
“We don't understand exactly what the process is, but it's something to take seriously,” says Cohen. “What we should learn from this is that using human-derived non-synthetic materials has risks, and not just with growth hormone. The HIV epidemic related to blood transfusions is another example. We should be aware of the risks of using human material without carefully assessing what the negative consequences could be.”
What Causes HGH to Increase Your Dementia Risk?
The synthetic form of HGH that doctors use for treating conditions today doesn’t have the risk of transmitting diseases like CJD or Alzheimer’s. Like any medication, it has some potential side effects and risks, but it’s an appropriate and safe therapy for people with growth hormone deficiency, says Cohen.
The HGH your body makes naturally can pose some risks, too. One of those risks is cognitive problems. Researchers know about these risks from studying people with untreated conditions that cause either too little or too much HGH in their body.
For example, people with acromegaly (a condition caused by too much HGH in their body) have an increased risk of cognitive decline later in life. Similarly, studies on the growth hormone-dependent factor IGF-1 (a chemical messenger in your bloodstream that manages the effects of HGH) show that both high and low IGF-1 levels increase dementia risk.
But as a rule, it’s not accurate to say growth hormone increases your dementia risk, says Cohen. The important takeaway from the risks that doctors do know about is that you want to have your growth hormone levels in the normal range, and treat any extremes that happen in either direction.
“We can say that excess growth hormone might be associated with cognitive decline, but only in cases of disease, not when it is being used as a treatment,” Cohen says. “In the case of adult growth hormone deficiency, studies actually suggest growth hormone replacement prevents health issues, including cognitive decline. So the answer is growth hormone doesn’t increase dementia risk, although severe hormone excess could be associated with cognitive decline.”
Is Alzheimer’s Disease Transmissible?
Alzheimer’s disease is not contagious, and you can’t “catch” it through routine care of someone who lives with it.
A few past studies suggest that Alzheimer’s may be transmissible in rare cases, in theory. The idea behind this theory is that beta amyloid proteins may act like misfolded proteins called prions.
Prions are proteins that clump together and continue to get deposited in your brain and cause brain damage. Both CJD and bovine spongiform encephalopathy (BSE, or “mad cow” disease) are caused by prions.
“There's been a lot of talk over the years about whether or not some neurodegenerative conditions like Alzheimer's or Parkinson's could sometimes be caused by prion-type diseases that are infectious in a sense, but not driven by bacteria or viruses,” says Cohen.
“The possibility that Alzheimer's disease can be caused by prions is difficult to weigh in on, definitively. The possibility continues to exist, but the actual prion agent, or cause of disease, hasn't been documented.”
For most Alzheimer's cases, the cause is genetic or lifestyle-related. Risk factors for Alzheimer’s disease include:
Today, people who need growth hormone therapy take synthetic growth hormones that don't carry the risk of contamination. Neurosurgeons also use new instruments for each brain surgery, so direct exposure to another person’s brain tissue is virtually impossible.
Should I Stop Taking HGH to Prevent Alzheimer’s?
If your doctor prescribes HGH to treat a condition you have, you shouldn’t stop taking it without talking to your doctor first. You should always consult your doctor before stopping or starting any treatment.
Doctors consider HGH a safe and low-risk treatment for growth hormone deficiency, a relatively common condition in children.
“We know they benefit from growth hormone treatments, and there's also a population of adults with growth hormone deficiency who also benefit from treatment,” says Cohen.
“In those cases where the growth hormone deficiency is clear, the medical community continues to recommend growth hormone replacement therapy. There is no evidence that these people will [have] an increased risk of Alzheimer's.”
Takeaways
HGH is a naturally occurring hormone in your body that some people also take in synthetic form to treat low levels of HGH. Recent research suggests people who took cadaver-derived HGH (now banned) have a higher risk of Alzheimer’s, because amyloid beta proteins are in their brain and spinal fluid. Experts say taking modern synthetic HGH to treat deficiencies doesn't raise your risk of dementia, and Alzheimer’s disease isn't transmissible through daily routine care.
