What is LSD, what does it do to your brain and the reason it’s not lethal even at large doses?
In: Biology
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LSD is believed to act mainly (although not exclusively) on some of the “serotonin receptors” in your brain. Serotonin is one of the many neurotransmitters that enables the brain to send signals through selective synapses, creating “circuits” that we interpret as thoughts, emotions, and perceptions.
LSD mimics serotonin well enough to bind to the receptors, but it doesn’t act quite like real serotonin. This causes parts of the brain to work in unusual (and somewhat variable) ways.
It isn’t lethal because it is apparently similar enough to the natural neurotransmitters to not cause a major malfunction in the brain. And while the human body has serotonin receptors in other places (most notably in the gut), LSD does not apparently disrupt them to the point of fatality either.
And while there are few (or no) credible instances of LSD overdose inducing death, in very large doses it can cause physical harm. Probably the most famous instance was when eight people snorted very large doses of crystalline LSD at a party, apparently thinking that it was cocaine. They were hospitalized, and some of them were put on life support. All eight survived.
LSD is a drug that has hallucinogenic properties– in other words, it can trigger you to see or hear things that aren’t really there. We actually don’t know much about LSD, since most scientists are more interested in studying drugs with a greater adverse societal impact, like nicotine, cocaine, or heroin.
However, we do know that LSD has a molecular structure very similar to that of another neurotransmitter called serotonin. This similarity led a lot of scientists to think that LSD must somehow affect serotonin transmission.
There is a cluster of neurons in your brain stem called the raphe nucleus, and almost all of the neurons that produce serotonin in your brain originate in the raphe nucleus. The raphe nuclei neurons then project to basically every other structure in your forebrain.
Studies in cats show that blocking serotonin receptors will block the behavioral effects of LSD. In humans, released serotonin is broken down by a molecule called monoamine oxidase. A class of antidepressants called monoamine oxidase inhibitors (MAOIs) will turn off monoamine oxidase, which will result in more serotonin in the brain. The way the brain works is that if you flood it with a neurotransmitter, it will try to adapt by reducing the amount of receptors for that neurotransmitter. So for people who have taken MAOIs for a long time, they will have lower amounts of serotonin receptors, in order to compensate for more serotonin in their brain. These individuals are also less susceptible to the effects of LSD. Furthermore, when attempting to synthetically create hallucinogens like LSD, it turns out that the better the drug binds to the serotonin receptor, the more potent its effects. These three lines of evidence lead to the idea that LSD works by binding to serotonin receptors somewhere in the brain.
But where? Well, let’s take a step back. Besides inducing hallucinations, what else does LSD do? Well, individuals who take LSD report symptoms of “oceanic boundlessness,” or this feeling of dissociation with the self, and feeling “at one” with the universe. They also report feelings of “anxious ego-disintegration,” where they feel completely removed from the self and feel like they have no control over their actions.
One idea is that it affects a network of neurons throughout the brain called the default mode network, or DMN. The DMN is composed of neurons that are MORE active when people are daydreaming, relaxed, or reflecting about the self. They also turn on when people are reminiscing about the past, or thinking about the future. In other words, the DMN looks like it activates when you’re engaged in personal, introspective sorts of thinking– activities of the “self”. On the other hand, if you’re actively looking for something or doing something, the DMN will turn off.
So maybe the DMN represents the “core self?” What will happen if the DMN is permanently turns off? One really interesting thing is looking at individuals with Cotard’s delusion. Individuals suffering from Cotard’s delusion wholeheartedly believe that they either dead, or do not exist. It turns out that individuals with Cotard’s delusion show significantly reduced activation of the DMN– in other words, it looks like that in order to have a sense that you exist as an entity, your DMN needs to be active.
Very interestingly, then, studies have shown that LSD actually turns off our DMN. The amount that an individual’s DMN is turned off by LSD correlates strongly with how much they experience its effects. Together, these results suggest that the DMN being active is at the core of having a sense of self. It looks like LSD binds to serotonin receptors in the DMN to suppress the sense of self, which can lead to people who take it feel disassociated with the self, or one with the universe.
Edit: The target audience of this response obviously isn’t literal 5 year olds. One of my pet peeves is that people who write on ELI5 often have no idea what they are talking about, and simplify their answers to the point of uselessness. My goal was to write a response that took a bit of effort to read, but would be as complete and accessible as I could make it. This is by no means the complex version of this answer, and if you’re confused by anything, I’m happy to elaborate. If you don’t think this is accessible **let me know and I will be happy to edit my post and make things more accessible**
I assume lysergic acid diethylamide.
I feel like the previous comments have already explained the scientific side really well. So, from a user’s standpoint, words honestly cannot do it justice. The psychedelic experience is amazing, beautiful, and indescribable. The visual effects are beautiful, music sounds godlike, lights and colors are pretty, life is positive and everything is love. Puts you in the most childlike and blissful state. My best friend and I tripped together, one time in particular, and we threw glow sticks at each other in my closet and I really did feel like a kid again. Listened to music and rolled around on the carpet. Sensations and feelings are heightened. A fuzzy blanket feels so good on the skin. Feels good to touch and be touched. Highly recommend it.
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In normal circumstances your brain’s various regions are isolated from eachother. You only perceive one at a time and they go through a part of your brain that acts like a switch keeping them from talking to eachother. LSD silences that switch and parts of your brain that never talk can now speak directly. This gives you weird perceptions, you see how the lower parts of your brain process information and imagery and the barrier that separates things you imagine from what you perceive becomes blurred the higher you go in dosage. This leads to things like seeing sound, or recognizing objects as other objects, having walls move etc. You’re just seeing raw unprocessed data that your brain normally hides from you.
There is another layer in your brain that acts as shortcuts. A good way of explaining it is when you take the same path to work everyday for months and then one thing changes and you suddenly recognize a building you’ve never seen before like it’s appeared out of nowhere. The truth is your brain through repeated exposure drew a line to useless information because you repeatedly told it that it wasn’t important. Then when it became novel because something changed your brains filtering is disrupted and you see it.
Thinking is expensive and at times uncomfortable so your brain is as lazy as it possibly can be and relies heavily on these shortcuts for everything. Depression and addiction can exist within this system, where people have issues/patterns that trap them mentally in circular thoughts they can’t escape. They cannot change their perception to adapt to their realities. When you take LSD in a dose high enough to induce ego death you are removing these shortcuts. This is where psychedelics can be transformative and it allows you to rewrite the shortcuts, to give new interpretation to events and circumstances. This allows you to figure out what view point serves you best which you can then use to let go of traumatic events, reorient your relationships and transform how you view yourself. You’d be surprised how many people truly hate themselves and how much it negatively effects their life in ways they are incapable of normally perceiving.
It may well be true that what we experience as our ego is just a series of ingrained mental shortcuts that while useful is not without its downsides. There are technical/scientific terms for everything I’m describing, but I find these descriptions do it justice. I have a decent explanation of religious experiences too, but I’ve been told it kills the mystery of psychedelics for some people.
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To be fair, as I recall there IS a lethal dose of LSD. Heck, there’s a lethal dose of plain water. In both cases, I think it’s physically difficult (though not impossible) to ingest that much due to volume limitations of our digestive system.
In other words, to take a lethal dose of LSD, you might have to drink more than your stomach could hold. You certainly couldn’t absorb that much any other way, at least not fast enough. Someone would probably have to keep feeding it to you steadily for a long period.
Of course, that much potent hallucinogen may kill you anyway, since you could easily forget to drink for more than 3 days (which is fatal), or have a fatal accident (walking into traffic or some other dangerous environment, oblivious to what is really around you, etc.). Obviously that could happen on even a short trip, but a really, really long one would multiply your odds for sure.
Hey follow up questions…
1) Is the trip like Mushrooms?
2) It’s not addicting right?
3) considering 2, why is it illegal?
When erratic, maladjusted, mentally unstable or just downright unlucky people take LSD, then things like “bad trips”, abuses of others and of the self, and lasting adverse psychological effects can occur. Lots of people have taken LSD though. No one has ever overdosed and died from toxicity.
In my opinion, LSD is much scarier and far more mystifying to people who have never taken it and will never take it.
When very smart and receptive people take these psychoactive drugs in a concerted way, amazing advancements in human understanding and technology are sometimes facilitated.
[https://en.wikipedia.org/wiki/Kary_Mullis](https://en.wikipedia.org/wiki/Kary_Mullis)
Read the bit about “use of hallucinogens”
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