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Enhancing the brain and drinking blood: The science behind 'Limitless'

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Mar 17, 2021, 1:30 PM EDT

Before Bradley Cooper voiced a cartoon raccoon, he played Edward Morra in the thriller Limitless, which turned 10 years old last week. When the movie starts, Morra is struggling to write a book, maintain a relationship, or handle the basic necessities of life. He's behind on his rent, his apartment is a mess, and he lacks the motivation and mental capacity to fix his problems. He dreams of a different life but in every respect, his reach exceeds his grasp. At least until he discovers NZT-48.

NZT-48 is a designer drug that maximizes his cognitive abilities. It gives him perfect memory and allows him to analyze details previously missed. With one pill, he cleans his apartment, solves his rent problem, and cranks out a draft of his book. The trouble is, the effects are temporary, and acquiring more of the miracle pill plunges Morra into a world of intrigue, potentially deadly side effects, and murder.

The film — which also spawned a single-season series of the same name in 2015 — hinges on the old myth that there are untapped cognitive reserves in our brains and that we could accomplish incredible things if only we could access them. It makes for good story fodder, but is there any truth to it?

THE 10 PERCENT MYTH

We've all heard that we supposedly "only use 10 percent of our brains." It's unclear where this myth originated, but its legacy lives on. Based on a survey from 2013, approximately two-thirds of respondents believed it to be true.

There's some logic here, however flawed. People have limits but are capable of seeing beyond them. It's reasonable to believe that if we can imagine ourselves operating at a higher or more efficient level, our inability to do so has some physical cause. We also see other people we deem as smarter, more talented, or simply more efficient than ourselves. They're using the same hardware, so what gives? How did Einstein unlock the secrets of relativity while the rest of us struggle to understand the complexities of everyday life? Surely, he tapped into some secret mental reserve that allowed him to more fully see the mechanics of the universe, right?

The reality is most of us use all of our brains all the time. The brain is a costly evolutionary adaptation. While it accounts for roughly 3 percent of body weight, it chews up 20 percent of our energy costs.

It might be one of the reasons human babies are born so helpless; the size of our brains in relation to the rest of the body, as well as the metabolic demands, necessitate a relatively early birth. By the time we're born, we're not really done cooking, so to speak.

Having offspring who need such intense care for the first few years of life comes at a high evolutionary cost — and evolution has a way of weeding out costly adaptations unless they pay off. In short, your brain is probably only as large and as energy-expensive as it needs to be.

Moreover, if there really were another nine-tenths of your brain waiting to be tapped, doing so should increase the energy demands 10-fold. That 20 percent of energy costs becomes 200 percent. You'd suddenly need twice the usual calories and that doesn't even take into account energy costs for other things like keeping your organs alive or running around evading shady loan sharks and white-collar drug dealers with your super-powered brain. Limitless people would also have limitless appetites.

IS NZT-48 (OR SOMETHING LIKE IT) REAL?

A quick Google search will unveil countless supplements promising to improve your memory or brain function. However, as a rule, there's a reason those things are sold as supplements and not from a doctor or pharmacy.

Supplements are regulated by the FDA as food, not drugs. They don't have to jump through all the usual hoops medications do for approval. They also aren't supposed to make explicit medical claims, but they usually get around this with clever language and suggestive marketing. If a supplement makes incredible claims yet didn't bother going through the processes to verify them, it's worth asking yourself why.

Surely, if there were a pill or a powder you could take to enhance your memory and cognitive ability, it would be a billion-dollar industry. And it is, sort of. Herbal supplements rake in roughly $35 billion a year, despite making dubious claims with mixed results.

Nootropics, a subset of the supplements targeted toward brain enhancement, make up a substantial portion of the market. They generally promise to boost memory and creativity or "lift brain fog," whatever that means. A review of common ingredients reveals little more than what you might get from some fruit, a multivitamin, or a cup of green tea.

Some of these supplements do include ingredients that have been shown to improve brain function in specific medical scenarios but found no effect on non-demented adults. If you're otherwise healthy, there's little to no evidence that dietary supplements will have any positive impact on brain function.

According to Dr. Guillaume Fond, a psychiatrist at the Aix-Marseille University Medical School, there's no drug on the market that effectively improves brain function. You're much better off eating right, sleeping well, and exercising. But that's difficult to bottle. The common image of the mindless meathead is probably not as accurate as TV and movies would have us believe.

There's evidence that exercise improves blood flow to the brain and releases hormones that support brain cell growth and plasticity. Research in gene therapy has found some success in improving brain function in rats, especially when subjected to stress.

The research, while not proven in humans, showed the possibility of reducing or eliminating the negative effects of stress or other negative factors by introducing an engineered virus into the brain. The researchers were quick to point out, however, that should this ever make its way to human use, it should only be used to mitigate already existing negative effects and not to boost the brainpower of otherwise healthy individuals.

For the time being, the best guidance for healthy adults who want to feel sharper is to put down the supplements and go for a jog.

DRINKING BLOOD

In one of the most outrageous scenes in Limitless, while suffering from NZT withdrawals and having just dispatched a foe, Morra does what anyone in his position would do: He drinks the NZT-laced blood pooling on the floor.

It's not the smartest move, as blood consumption has all sorts of associated risks. There is, of course, the risk of contracting blood-borne illnesses. But even assuming the blood is pathogen-free, it's toxic when consumed in sufficient doses.

With all of that in mind, it is possible to acquire the effects of a drug up the food chain. While this scenario is mostly relevant in terms of drugs given to animals intended for consumption, the same rules apply in a human blood-drinking situation.

There's some guesswork involved in the case of NZT, a wholly fictional drug, but assuming it works in similar ways to real-world drugs, we can make a few assumptions. It's well documented that people historically have consumed the urine of reindeer who earlier consumed psychedelic mushrooms. The psychoactive compound passes through their bodies and is excreted. Consumption of said urine, while unsavory, passed on the psychedelic effects.

Likewise, hormones and antibiotics given to farm animals spread throughout their bodies and into their tissues and can pass up the food chain if consumed before the half-life of those drugs is spent. The primary mode of proliferation through an animal's body, human or otherwise, is through the blood. So, it stands to reason that consumption of blood with sufficient concentrations of a drug would pass on at least some effect, provided the active compound is effective when consumed.

The question then becomes one of concentration, but it isn't outside the realm of possibility. All things considered, it's probably not worthwhile to drink the blood of a sworn enemy when a cup or two of coffee or tea will do. Let's not get carried away.