The Case for Brain-Only Preservation

Is brain preservation superior to head-only preservation?

One of the most important cryonics decisions a person needs to make is whether to select “neuro” (i.e., head only) or “whole-body” arrangements. A lot of (virtual) ink has been spilled on this “whole-body vs neuro” question. I have written a detailed article with Alcor Director Michael O’ Neil in favor of whole-body cryopreservation. One of the major arguments that we use in our article is to extend “Pascal’s wager” (or “Merkle’s wager”) argument in favor of cryonics to the choice of cryopreservation method itself.

One element of the “whole-body vs neuro” debate that is rarely mentioned is that for organizations such as Alcor, it is often a meaningless debate. If cost is not the main reason for choosing neuropreservation, you can actually have your cake and eat it too by making arrangements to do isolated head perfusion but include the whole-body for long-term storage.

Notwithstanding my own preference for whole-body cryopreservation, in this piece I would like to make a case for brain-only cryopreservation. In particular, I will make the case that arguments in favor of neuropreservation apply even more strongly to brain-only preservation and there are some advantages to brain-only preservation that neuros cannot avail themselves of.

Let’s start with a potential objection. It has been argued that the advantage of neuropreservation is that brain removal could damage the brain and “storage” of the brain in its skull is safer. Naturally, if a brain would be removed from the skull in a reckless manner and stored without meaningful support, that is most definitely the case. However, if the brain is removed with good surgical care at low temperatures, and the brain is transported and secured without inducing compression damage (resting on a net, dacron wool etc.), safe brain removal is technically possible. In fact, in 2014 Chana Phaedra published the first protocol for isolated brain removal for human biostasis purposes.

What are some advantages in favor of brain-only cryopreservation?

Cost. Long-term storage costs for isolated brains are at most 50% of “neuro” and probably even lower. That can potentially translate in long-term storage costs being tens of thousands of dollars lower, which can bring the procedure within the reach of people who can only do a cash payment instead of using life insurance.

Logistics. In case of emergencies (or relocation), cryopreserved brains can be transported even more easily than isolated heads. More importantly, given their “organ” status, destinations for such brains may include organizations that would not be inclined to store isolated heads.

PR. Neuropreservation has a serious “yuck” factor that does not exist for brain-only cryopreservation. In fact, of all three “visuals” (a dead body, a severed head, an isolated brain), the naked brain fairs the best.

Organ Donation Compatible. In principle, brain-only preservation is compatible with whole-body organ donation. In ideal circumstances this option could be pursued in a way that benefits both the quality of brain preservation and organ donation.

Public Ceremony Compatible. Brain-only preservation is compatible with a burial ceremony (or even cremation), which could yield greater acceptance and support by family members. This advantage is not available for neuropreservation (to put it mildly).

Fracturing Reduction. All other things the same, fracturing scales with sample size and tissue heterogeneity, which favors brain-only cryopreservation in terms of mitigating thermal stress at low temperatures. Given its lower long-term storage cost, brain-only cryopreservation also permits more affordable intermediate temperature storage (ITS).

Permits Emergency Fixation. In case there is an unexpected, long-term, liquid nitrogen delivery issue, isolated brains can be immersed in a chemical fixative to prevent decomposition.

This last advantage suggests another advantage for brain-only preservation. Isolated brains can be immersed in a chemical fixative (such as glutaraldehyde), followed by immersion cryoprotection, a procedure I have called “immersion vitrifixation” (or iVitrifixation).

While fixation by perfusion, followed by cryoprotectant perfusion, remains the gold standard for aldehyde-stabilized cryopreservation, there are a subset of cryonics cases where meaningful perfusion is not possible because of extensive ischemia. Instead of doing a “straight freeze” (freezing without cryoprotectant), chemical stabilization, followed by immersion cryoprotection, can still yield ice-free cryopreservation. Immersion vitrifixation takes advantage of the principle of mainstream hypothermic organ preservation that at low temperatures metabolism is reduced at a faster rate than diffusion of a chemical. At this point, iVitrifixation protocols are still in the exploratory stage and under active investigation by Biostasis Technologies.

Currently, of the major cryonics providers, brain-only cryopreservation is only offered by Tomorrow Biostasis, but it is conceivable that cryonics organization that are concerned about the negative PR associated with neuropreservation, may add this low-cost option to their services.