The California anti-aging therapy startup Alkahest launched a small clinical trial back in 2016. Subjects suffering from mild to moderate Alzheimer's disease received four weekly infusions either of plasma—the liquid, cell-free part of blood—obtained from donors 18 to 30 years old, or of a placebo (a saline solution).
The trial was inspired by heterochronic parabiosis, a technique in which scientists grafted young and old mice together so that the animals shared their circulatory systems. The result was that the older mice's muscles, livers, hearts, brains, and other organs and tissues were rejuvenated significantly.
In my 2015 article "The Vampire Cure for Aging," I explained that Alkahest wanted
to see if infusing blood plasma from young people into patients suffering from mild to moderate Alzheimer's disease will improve their cognition. The company expects to enroll 18 patients in the coming trial, half of whom will receive infusions of human blood plasma donated by men under age 30 once weekly for four weeks. The other half will receive saline. The trial will chiefly focus on the safety of the treatment and compliance by participants. Additionally, researchers will compare both groups to see if those treated with blood plasma perform better on a number of tests for Alzheimer's disease and if changes suggestive of cognitive improvement can be identified in their brains.
Alkahest is now reporting the results of the trial at various scientific conferences. As it happens, the company was able to enroll only nine patients in the randomized double-blind portion of the trial while including nine others in the open-label portion, in which all the subjects received transfusions of young plasma. An analysis of assessments once all participants had been treated showed no significant changes in participants' mood or their performance on tests of cognition involving tasks such as memorizing lists or recalling recent events. However, on two of three different caregiver assessments of functional abilities such as making meals and shopping, participants showed statistically significant improvement.
Other researchers have pointed out that it is hard to draw conclusions from such a small trial that lasted for such a short time. In Science, neuroscientist Zaven Khachaturian observes that the positive effects reported by the caregivers could merely be a placebo effect: "[Patients] could feel better because somebody paid attention to them."
In any case, the company announced, "We look forward to advancing our lead clinical candidate, a proprietary plasma fraction, as a potential treatment for mild to moderate Alzheimer's disease." Their proprietary formulation will largely contain growth factors found in blood plasma.
Another California biomedical startup, Ambrosia, is running a "clinical trial" that transfuses plasma from people aged 16 to 25 into folks willing to pay $8,000 for the treatments. Some 600 people so far have reportedly signed up for the study. Since there is no placebo group, the company is reporting reductions in various blood biomarkers, including some associated with risks for cancer, cholesterol levels, and amyloid proteins associated with Alzheimer's disease.
In reporting on Ambrosia's anti-aging treatments, my colleague Mike Riggs recently asked, "Is It Wrong for Old People to Receive Blood Infusions From Teenagers?" As long as they're doing it voluntarily, my answer is no. Riggs further observed:
There are nearly a billion humans over the age of 60 on the planet today. There will be more than two billion of them by 2050. I hope to still be around then. I'm sure many critics of parabiosis hope to as well. If the tech bros of Silicon Valley want to offer up their bodies and their money in hopes of making that possible, why would any of us discourage them?