A local embalmer could begin brain preservation if the team cannot arrive in time, says a staff member at Sparks, an organization that preserves brains after death

A local embalmer could begin brain preservation if the team cannot arrive in time, says a staff member at Sparks, an organization that preserves brains after death

On October 27, Sparks staff member Andrew McKenzie published an essay on LessWrong. He proposes having an embalmer administer formalin through the carotid arteries as soon as possible, then shipping the brain or body to Salem, Oregon, where Sparks would continue the preservation process.

Sparks preserves brains on the premise that long-term memories are encoded in brain structure and that future technologies might be able to use that structure to revive a person. Immediately after death, a solution containing aldehydes such as formaldehyde is perfused through the brain's blood vessels to fix its structure. The longer the delay, the less effectively the solution flows through the vessels, the organization notes.

For people far from Sparks, McKenzie estimates that a mobile team is unlikely to arrive within 4 to 12 hours, or even within a day. He suggests turning to local embalmers, who in many places already perfuse aldehyde solutions through the blood vessels of deceased people.

Researchers have done little direct research on how standard embalming solutions affect the brain, McKenzie writes, “probably because they simply do not care very much about it (and why would they?).” The available evidence comes from forensic pathology studies of embalmed bodies, in which, he says, tissues are generally preserved well enough for diagnosis. His assessment of how well fine brain structure is preserved rests on the action of formaldehyde itself, which in an embalming solution “does what an aldehyde is expected to do: it preserves tissue structure very well.”

He expresses greater confidence in standard 10-percent neutral buffered formalin (about 4 % formaldehyde), which embalmers generally do not have on hand. If an embalmer obtains it and administers it as soon as possible through both common carotid arteries toward the head, McKenzie expects the brain to be preserved quite well.

McKenzie draws on a study by Ricardo Insausti's group in Spain. The researchers flushed the blood vessels with saline through both common carotid arteries, then administered 4-percent paraformaldehyde, which McKenzie considers to act much like formalin. The group judged brain preservation to be roughly comparable to that achieved in laboratory animals when the interval after death was less than 10 hours for several research methods, or less than four hours for electron microscopy.

McKenzie considers the flushing step used by Insausti's group unnecessary because it complicates the embalmer's work. In a paper he coauthored (77 body donors), flushing was used only in the first two cases; formalin was administered directly in subsequent cases. The authors suggest that flushing may be unnecessary because formaldehyde fixes tissue much more slowly than the solution displaces blood, leaving little time for clots to become fixed. However, in the initial experiments, administering the solution through the same common carotid artery route sometimes directed it into facial tissues, largely bypassing the brain, particularly more than a day after death.

To McKenzie's knowledge, Sparks is the only organization in the world that accepts brains or bodies embalmed elsewhere. He writes that it chose aldehyde fixation because the evidence for structural preservation was stronger, and only later recognized the possibility of remote embalming. He considers embalming sufficient for transport but insufficient for long-term storage.

Sparks offers this arrangement to residents of Alaska, Hawaii, and other countries: brain preservation after local embalming costs 7500 dollars, excluding local services and shipping. In the continental United States, it sends its own team: the standard service costs 45 thousand dollars, primarily to cover the team's deployment. McKenzie sees the embalmer arriving too late as the main risk and advises making arrangements with both the embalmer and Sparks in advance.