A startup company in California called Alkahest has an unconventional, and rather vampiric, idea for curing Alzheimer’s disease. The founders believe that the disease can be slowed, stopped, or possibly reversed using blood from young people.

Well not “blood” exactly, but plasma, which is all the fluid left behind after you remove the cells from the blood. And right now, a small sample of patients with Alzheimer’s disease are receiving weekly injectionsof plasma donated by healthy, young people as a potential treatment.

Research behind the healing capacity of young blood has a long history. In the mid-1800s a French scientist named Paul Bert developed a technique called parabiosis. Here, two mice are sutured together so that they share a common bloodstream. You can pair a sick mouse with a healthy mouse to ask how blood from one mouse affects the other. Despite the gruesome tableau, these experiments have yielded fundamental information about how aging occurs.

When a young mouse is paired with an old mouse, the benefits on the old mouse can be profound. Older mice have better memory, heal faster, and are more agile when they share a bloodstream with a young mouse. Yet, interestingly, no one has convincingly shown that young blood can extend the lifespan of a mouse.

There are two glaring weaknesses for interpreting parabiosis experiments. First, it obviously doesn’t translate into a reasonable therapy- no, we will not be stitching old people to young people. And second, it only tells us that something in the circulation of a young person promotes healthy aging.

Fortunately, in recent years, scientists have found that infusing old mice with plasma from young mice has similar rejuvenating effects to forcibly conjoining them. Subsequently, research has shifted from focusing on parabiosis to plasma transfusions. This method is more translatable to human medicine, and it’s easier to control in laboratory settings, which is important for helping us understand which factors promote healthy aging.

A few years ago, a group of researchers from Stanford found that plasma from young mice can increase cognitive function in mice with Alzeimer’s disease. Sounds promising, but mice are very different from humans, so on to the next step: clinical trials, where most exciting therapies fail to show an effectct.

This is where Alkahest comes in. They have accepted the challenge of running clinical trials to find out if recent research can translate into a therapy. They presented some of their results at a recent Alzheimer’s disease conference in Boston. Unfortunately, the 18 patients who received weekly injections of plasma from 18 to 30-year-old healthy males barely improved on cognitive tests compared to patients who received a placebo.

But there is still hope for this trial, which Alkahest plans to continue with a larger group of enrollees. According to surveys taken by caretakers, the patients receiving plasma did not require as much help with daily tasks, such as traveling, cooking, or getting dressed.

So could this work? Will we eventually live in a world where plasma is a common treatment for Alzheimer's?

It’s easy to picture this research taking a dystopian turn, where young, poor people donate blood to rich people who can afford plasma infusions. There is already a startup called Ambrosia, where anyone can receive injections of plasma from young people for the price of $8,000. The rich can literally feed on the blood of poorer, younger folks.

But we might be able to avoid this situation if we identify the factors in plasma that promote health in patients with Alzheimer’s – that is, if research like Alkahest's, unsavory though it appears, results in identifying what, exactly in younger blood benefits older people (and mice). Perhaps one day these can be synthesized, and given as a more directed treatment, eliminating the requirement for people to donate blood.

In 2014, researchers identified a protein in mice called GDF11 which regulates stem cells and decreases as mice age. They found that when old mice are injected with GDF11, they are more agile, they heal muscle faster, and they have healthier hearts. Perhaps GDF11 also has benefits to mice with Alzheimer’s. Clinical trials like the one by Alkahest may help us answer these questions.

Until this therapy has been properly vetted through clinical trials and approved by the FDA, you should remain skeptical about companies, like Ambrosia, that offer an expensive service based on incomplete data – and there are so, many, other examples. Sometimes it can be hard to determine which treatments have support and which ones are just snake oil.

Ask a doctor or a scientist before trying something new. If you can't find a professional, a good rule of thumb is that if they use the phrase scientifically proven, they're trying to sell you something. Have you ever noticed how scientists don't use that phrase?

There are many interesting and exciting therapies on the horizon, but science and medical advances take time. So be patient and hold onto your own plasma for now.