Dissociation - What is it really?

Dr. O'Leary explores the neuroscience of dissociation, defining it as a degenerate concept that refers to a wide range of functional disconnections within the brain rather than a single clinical entity. The discussion moves from the standard medical definitions—such as depersonalization, derealization, and amnesia—toward a broader view of dissociation as a neurobiological defense mechanism that uses sensory attenuation to manage background noise and overwhelming trauma. By examining how specific regions like the temporal parietal junction and the default mode network integrate our sense of self and environment, Dr. O'Leary compares how disruptions in these areas lead to the fragmented reality experienced in various psychiatric conditions. This discussion aims to shift the listener's perspective of dissociation from a vague symptom to a complex breakdown of mental integration that can be induced by drugs, trauma, or even intentional meditative practices.

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Welcome to Psychactic. Today is Monday, February 2nd, 2026, and I am your host, Dr. O'Leary, a second-year child and adolescent psychiatry fellow in the National Capital Region. This is a podcast about psychiatry, psychology, and neuroscience. Today, I'm going to review some of the most up-to-date knowledge we have regarding the neuroscience of dissociation. Dissociation is a word that has a life of its own, both in technical circles and on social media. It's often used so vaguely that it appears to lack any meaning beyond, I felt weird. After you listen today, though, I hope you have a better appreciation for what dissociation is in any particular context. I produce this podcast alone, occasionally with the help of some AI, so everything presented here is my responsibility, and nothing should be considered the opinion of anyone else, including the U.S. Federal Government, Department of Defense, Defense Health Agency, my friends and colleagues, or the Flat Earth Society. During my residency, I struggled with the word dissociation. I struggled so much with it that I did a previous podcast on it, and that helped, but it wasn't very satisfying. So I continued my search to understand this word. And like so many other things in psychiatry, dissociation is not itself a thing. It's a category, a degenerate concept, which means it refers to many disparate things. Dissociation is a relativistic term. It's a relative disruption in how our brain normally integrates itself. Another term for this is functional disconnection. And these disconnects often result in phenomenological experiences. I love that word, phenomenological. That just means that we have some awareness that something is not right in our brains, and our brains are trying to figure out what the error is so it can correct it. So we might lose, for example, our internal dialogue or our sense of self or identity. We might lose the feeling that things are stable and coherent through time. We could be dissociated from access to our memories. The present could seem completely unrelated to any other point in time. It could refer to our ability to estimate the passage of time and to know what came first and what followed. And more generally, dissociation is really a breakdown or discontinuity in the way fundamental mental processes typically work together to create reality. For those who know the DSM, I'm using a definition of dissociation that is far more broad than what they use. The more I learn about dissociation, the more it seems obvious to me that many disorders in the DSM that are not in the chapter dedicated to dissociation are also frequently dissociative. For example, functional neurological impairments like the sudden inability to feel or to move a body part, or the feeling that a body part is not actually a part of your body, most likely results from a dissociation of the normal causal mechanisms in the brain. The desire to move is dissociated from the actuation of movement. Many symptoms of catatonia likely arise because of dissociated mental processes. I believe that thinking about dissociation as a much more complex, heterogeneous, and degenerate concept than the DSM suggests is necessary to truly understand how our brains work and why many of our patients will report symptoms as diverse as numbness, anhedonia, and disembodiment. Having a better grasp of dissociation can also help us understand, better treat, and have greater sympathy for our patients. The DSM formally recognizes only a few types of dissociation. These are depersonalization, derealization, amnesia, and dissociative identity disorder. Depersonalization is the experience of feeling detached from and as if one is an outside observer of one's own mental processes or body. Individuals might feel kind of robotic, like a stranger to themselves, or disconnected from their emotions or the physical sensations they're receiving. It basically involves a loss of ownership over one's own body or sense of embodiment. The next is derealization, and this involves an experience that the external world is kind of strange or unreal. The environment might be perceived as dreamlike, foggy, lifeless, or distorted. Individuals might also feel detached from their surroundings. Things outside of them appear fake, odd, and not really what they appear to be. Dissociative amnesia is an inability to recall important autobiographical information, and this often happens during trauma. And the forgetting has to be more extensive than what can be explained by normal forgetting, because we all kind of forget things, and that's not dissociative amnesia. So amnesia can be kind of time-localized or episodic, so there's a loss of a memory for a very specific period of time. It can be very selective, like a loss of a memory for some but not all, events within a period, or it can be more generalized like a complete loss of one's life story. A dissociative fugue is considered a subtype of dissociative amnesia, where along with memory loss, there appears to be kind of a purposeful wandering away from home or from work, and you go and basically live a different life. And during this time, you continue to care for yourself and survive. It's very similar in some ways then to dissociative identity. But dissociative identity disorder, which is formerly known as multiple personality disorder, is really distinct. And we could get into this in tons of detail, which I will probably in the future, but not here, because it's too much. But DID involves a disruption of identity characterized by two or more distinct personality states. So this disruption is associated with a distinct discontinuity in the sense of self and of will. And it's accompanied by changes in your affective state, your behaviors, your conscious awareness, memory or perception. And there are many different ways that people describe their dissociative identities. But we'll get into that in the future. You don't have to have a dissociative disorder to experience a type of dissociation. In fact, dissociation is very common in normal day-to-day experiences, like when you lose time while you're driving, or you suddenly don't recognize your surroundings for a few seconds and then you finally do, or you get lost in thought and don't notice that your spouse is calling your name. Not that that has ever happened to me. Dissociative states are also relatively common in traumatic and post-traumatic experiences. They're also common in what we call borderline personality disorder. I've mentioned they are probably common also in catatonic states and in psychotic states, and even in confabulation when someone's telling a demonstrably untrue autobiographical story, but they appear convinced that that story is in fact true. That could involve a functional disconnect of different parts of the brain. Earlier, I made a comment that dissociation is a relativistic term, and I meant that in multiple different ways. One of those ways is that dissociation describes a state that is relatively abnormal compared to the typical functioning of our brain. Another way that it's relativistic is that dissociation is very often caused by the brain being unable to precisely place something in context like space or time or both. Space-time. In the most general sense, dissociation is a partial disintegration of normal brain functioning that can be consciously perceived by the person experiencing it, or identified in someone else by an observer. Let's hang that thought out to dry there for a little while. And while you ponder it, I'm going to discuss some of the phenomenology of dissociation because it's not always debilitating or distressing. Have you ever been able to put yourself into a flow state? It's a state where your attention feels almost effortless. You're immersed in some activity like reading, writing, music, digging, cutting, dancing, running, imagining, meditating. The world around you seems to dim and become dull. Sounds become droning hums, and the heat of the sun pounding on your neck fades into mere warmth. But then suddenly you become aware that someone's calling your name. Ryan, are you okay? I've been calling you. So I admit, this has happened to me many times. Dissociative experiences like that can involve various processes that attenuate other parts of the brain. Attenuation just means that they lower the volume of other parts of the brain. Sensory motor attenuation can be fun, relaxing, and useful, such as when you really need to focus on something and block out all the other noise, or you're really into what you're doing, and it's very pleasurable. But in a more extreme form, attenuation is a crucial neurobiological defense mechanism aimed at managing overwhelming internal and external stimuli, which we often refer to as trauma. Abnormal dissociative experiences occur when there is an overmodulation or excessive attenuation of one brain region by another. That's one way to get there. Overmodulation or excessive attenuation is often described as top-down, such as when our executive networks attenuate our emotional responses after we've been startled, because we realize everything's okay. So we don't have to be afraid. When we're overwhelmed and trapped with no physical escape, it may be the only possible escape is to disconnect our awareness of the pain, shame, betrayal, and incomprehensibility of the world around us. Top-down dissociation is an active inhibitory response that effectively dampens or even cuts off access to emotional and sensory input and can even block motor output, leading to feelings like detachment, emotional numbing, weakness, or paralysis. This overmodulation is often described as a psychological defense. In its more extreme forms, this defense allows individuals to mentally escape when physical escape from a traumatic or highly stressful situation is impossible. And it might also have had some survival benefits in certain situations in the past. Some people say that for most or all of human history, the most dangerous thing for a human was another human. And this is especially true in the case where there's an aggressive male and he's trapped a female. Resistance in this case for the female will almost always result in further injury and possibly in death. So when escape becomes impossible, tonic immobility and detachment might be the next best thing. It's a sad inheritance. So top-down attenuation can lead to things like sensory hyposensitivities. This is basically reduced responsiveness to or awareness of sensory inputs. It could result in a detachment of the normal sense of self or body, depersonalization or disembodiment. It could result in a detachment from the normal sense of reality, what we call derealization, which is altered perception of the surrounding environment. It can also result in emotional numbing, something called de-affectualization. So this could be a profound lack of emotional responsivity, a sense of being emotionally dull or flat, or even feeling dead inside. Attenuation can also result in analgesia, which is an inability to feel pain or a reduced ability to feel pain. So hypnosis or other ritualistic practices like acupuncture can be used in special cases for susceptible individuals to dull or disconnect a person from the pain. And now the power is not in the hypnotist or the acupuncture needle, but instead it's in the ability of a person under the care of a hypnotist or acupuncturist to enter a dissociated trance-like state. And not all people can achieve this. Another part of sensory attenuation is interoceptive silencing. So this is just a down regulation of all the signals coming from inside the body. So you may not feel the hunger, you may not feel the need to urinate or defecate. Now there are many ways to induce dissociative experiences intentionally, and humans over history have tried many things to voluntarily induce dissociative experiences. You might say that Buddhism itself is founded on a practice of dissociation of the self in an attempt to achieve nirvana. Selflessness, that feeling that you have no self, is achievable. Other religious practices have utilized dissociative states to do things like gain access to the spirit realm. But scientific researchers induce these states to study them. College students induce these states to party or to expand their minds, dude. Hypnotists attempt to heal the afflicted by inducing these states. At least you hope that's what they're doing. Now, here are a few of the ways that we can, with pretty good reliability, induce dissociative experiences in humans. And one is through virtual reality. Researchers have used VR to investigate sensory integration and can induce self-reported feelings of disownership of certain sensations or even of a person's body. And this is achieved by lengthening a delay to a virtual feed between the visual information that the person is getting in the virtual feed relative to the other senses, things like touch or sound. You keep lengthening this delay, and the larger the delay is, the more the person reports a kind of subjective disownership of an experience. And basically, sensations don't really feel real. They don't feel personal, like they belong to you. A classic example of manipulating body ownership via virtual reality uses a far more basic technology than VR goggles. It uses a rubber arm, and this is called the rubber arm or the rubber hand illusion. So in the rubber hand illusion, a participant can view a fake hand that's placed in a position on a table next to your own hand that's resting on the table, and then a screen is placed so you can't see your own hand, you can only see the rubber hand. The illusion begins when the rubber hand and your real hand are touched simultaneously while you're watching. Now, this can induce a sense of body ownership over the fake hand. But it can also induce a dissociation of sensations coming from your real hand. So often people will not feel sensations like cold ice caressing by a feather or sharpness of a needle applied to their actual hand, but will instead report being able to feel those sensations as they see them being applied to the fake hand. Now, not everyone will be able to do this, but many people can. This skill requires both dissociation of their real limb and adoption or association of the fake limb to their internal body model. Now, because the brain already knows what ice, feathers, and pens feel like, it internally generates the sensation without any sensory signal whatsoever coming from the rubber hand. And it also blocks sensory signals coming from their attached arm, because you can't have two hands. That doesn't fit with the brain's model. Another way that we often induce dissociative experiences is through script-driven guided imagery. So scripts are read in a way that are intended to provoke specific experiences, including dissociative experiences, by having a participant recall personalized narratives of autobiographical situations, and these are very frequently traumatic ones. So exposure to trauma-related memories via script-driven imagery has been used to induce certain dissociative experiences, like re-experiencing something that happened in the past in patients in order to help them to, over time, cope better with those states and heal those states. I've already talked about hypnosis, but mindfulness is similar to hypnosis in some ways, because you can use mindfulness and hypnosis with scripts to help people to dissociate. So in mindfulness, a script often asks participants to notice sensations and then move away from that sensation toward another, and this can induce a relative attenuation of the sensation that they're moving away from, as they're intentionally placing their attention somewhere else. And this takes advantage of your body's healthy ability to sensory attenuate as you're shifting attention. Now, in hypnosis, there's often an induction phase, and this can be script-driven frequently, where people who are susceptible to this trance state follow a procedure in order to enter that state. A trance state is a more profound type of attenuation than a mindful state, and it often can induce things like amnesia or anesthesia in patients. Aside from rituals like these, we can induce dissociative states with drugs. Some drugs like ketamine and phencyclidine, or PCP, are known to induce dissociation, analgesia, pain relief, hallucinations, and sedation. And they do this by antagonizing receptors called NMDA receptors. Now, these drugs can cause a spectrum of dissociative and psychedelic effects, including perceptual distortions and transient feelings of being detached from the self or from their environment. The over-the-counter cough medicine, dextromethorphan, is also an NMDAR receptor antagonist, like ketamine and phencyclidine. But it doesn't cross the blood-brain barrier very well, so you have to use very large amounts of it if you want to induce that effect. And doing that is called robotripping, where people used to drink an entire bottle of robotussin in order to try to force enough of the dextromethorphan into their head that they could induce these kind of psychedelic or dissociative experiences. Dextromethorphan can also be combined with medications that reduce its metabolism so that it stays in higher states within the body, so that that can allow it to cross the blood-brain barrier in small amounts. The drug Avwelty, it's a newer drug, uses a combination of bupropion and dextromethorphan to treat depression. Another way people have done this for a very long time is by using salvia divinorum, and so it's a kind of sage, and it's a potent dissociative hallucinogen. Now it's proposed to induce its mind-altering effects by activating something called kappa opioid receptors, or cores, KORs, in a part of the brain called the clostrum. The clostrum appears to be associated with a wide variety of dissociative experiences, including depersonalization, derealization, loss of time, amnesia, synesthesia, which is when one sense induces you to feel another one sort of like you see yellow and you feel cold at the same time. But the problem with Salvia divinorum is that it can also cause intense dysphoria. So people can get sad or scared. Um, and this is probably why it's not used more often. It's very likely to give you a bad trip. Another more common hallucinogen is psilocin, which is what your body turns psilocybin into. And it's similar to LSD and DMT, because they're all serotonin 2A receptor agonists. And serotonin 2A receptor agonists massively alter functional connectivity between many different brain regions, so this induces kind of A widespread dysregulation of cortical activity. And users often report many different kinds of experiences and odd perceptions, altered consciousness, and sometimes even like a loss of self or ego dissolution, or mystical type experiences where they kind of feel like there's really no boundary between them and the rest of the world. Instead of them feeling that the world is unreal, they feel like the world is, in fact, them. Now, psychedelics are also thought to enhance suggestibility, even for those who are not generally that suggestible. So this can be used therapeutically, such as in psychedelic-assisted psychotherapies, which are becoming more popular. Or it can also result in people being taken advantage of because they're a lot more suggestible now. And people will do things that are completely out of character if prompted. Now, there are many more substances out there that can induce similar experiences, and I don't have time to discuss them all today. Instead, I want to move on to talking about some of the functional brain regions involved in different types of dissociation. These are regions that we have identified as frequently being associated with certain types of dissociation. So let me start with a part of the brain called the posterolateral cortex, especially the temporal parietal junction or TPJ. Because the temporarietal junction is responsible for multisensory integration, and it also helps to construct our sense of embodiment. The TPJ is located on the outer surface of the brain where the temporal lobe and the parietal lobes meet. So this is a little bit, you know, kind of back on your head. So if you put your hands right behind your ears on your head, that's close to where the temporal parietal junction will be underneath your skull. It's a crucial hub for integrating multisensory information like proprioceptive information, our body and space, tactile information, you know, touch, visual information, and vestibular information, which is uh things like are we accelerating or are we still? And this helps us form a coherent sense of our physical body and space. And disrupting part of the TPJ called the angular gyrus can induce out-of-body experiences. So this is where you feel a lack of ownership of your own body, or you might actually feel as if you are not located within your own body, but sort of located slightly behind your own body. People will often describe feelings of kind of watching themselves like they're in a movie, doing things but not feeling like they're the one doing them. Another part of the cortex, if you start where the TPJ is and just sort of go a lot deeper into the brain, onto the surface of the cortex that's right there in the middle where the brain folds in over itself, you get to the posteromedial cortex. Now, the posteromedial cortex is a part of the brain that contains structures called the precuneus and the retrosplenial cortex. These are all part of something called the default mode network. And the default mode network is very important in constructing our sense of self, not as a body, um, but sort of as an identity, an ideal self. So patients with disruption in these areas often report feeling like they're disconnected from their own thoughts or their own internal narrative. Uh they don't really lose consciousness, but rather they kind of become an observer of their own mind, not necessarily their own body. Some people will report uh feeling like there is a presence or a duplicate sense of self that it exists within them, possibly multiple selves. But quite frequently it's just a feeling of existing without an identity. If you are a Buddhist, you might call this a state of pure consciousness, being kind of devoid of any personal history, being one with everything. It's a state that you would intentionally induce, a loss of self. Now the retrosplenial cortex is part of the posterior medial cortex that helps us to navigate. And so dissociation of function in this part can cause a sudden loss of where we are. So the room might feel physically distant. Um you might have to reach out to the wall to touch it to be like, is it close to me or is it far away? I can't tell. People with damaged dys region will often describe things like viewing the world like it through a long tunnel, or kind of like a view from nowhere. Like they can't locate themselves in relationship to other things. They can see their surroundings, they can recognize people, but they don't feel like they're part of the scene. So the posterior lateral parts of our cortex, especially the TPJ, help to integrate senses and produce an emergent sense of embodiment, while the posterior medial parts, like the retrosplenial cortex and precuneus, appear more concerned about the self and the self's relationship to things around it. There are many, many other places in your brain where you you could experience dissociative phenomena if they're messed up. For example, like the thalamus is a huge um gate for sensory signals coming in. So if there is a problem with the thalamus, the cortex might not receive sensory signals that it's expecting and it could feel dissociated because of that. Um, or if there's a problem with the thalamus, which helps different parts of the cortex to coordinate in real time, that can cause senses of dissociation. And then I mentioned the costum before, and the costrum really seems to be very helpful for helping us to integrate our conscious experiences into sort of a perceived whole, unified and present through time experience. But I don't want you to leave thinking that I'm saying that each of these brain regions does that, like that's their job. What I'm saying is that if you mess with these regions, you get these phenomenon in a lot of people. And so they are often involved in producing certain types of experiences, but I wouldn't say they are like the brain's region of that. It's far more complex. The brain works through functional connections, not through producing a sensation in a single region and then sharing that sensation with other brain regions. I talked about recently over-modulation of brain regions. So that's where there's too much sensory attenuation, for example. The brain's dampening down another part of the brain so that it can really focus and spend all of its resources in one area. But there's also under-modulation where the brain should be kind of attenuating things, but it's not. So this can result in a flood of signals coming through that would normally be orderly, kind of gated, and possibly even ignored. What I'm talking about here are things like hypersensitivities to certain sensory stimuli, hyper-arousal, severe anxiety, extremely impulsive states like mania. In these, the normal process of attenuation is not working. And so you get too much functional connectivity when you shouldn't be having it. And this can result in re-experiencing things that aren't there, experiencing things like paranoia. I I'm I I know that person saw me and I know they're thinking about me, and and they probably can even read my thoughts. So this may occur because of a lack of attenuation where you have dissociated from a sense of reality because your brain can't pay attention to the normal signals that it would get from, for example, your executive centers that would say, you know what, that doesn't make a lot of sense. Um, why don't we consider another option? So this could be a dissociation in a functional way where you have the inability to attenuate salience signals and say, that's actually not all that important. And so you now can't have the same functional connection you did before with your executive centers of your brain, like the dorsolateral prefrontal cortex. Hyper-arousal is also linked to a loss of function or reduced functional connectivity between areas like the perioqueductal gray matter and something called the bed nucleus of the stria terminalis, with the dorsolateral prefrontal cortex and the ventromedial orbital frontal cortex. And so those last two things, the dorsolateral prefrontal cortex and ventral medial orbital frontal cortex, are part of our executive networks. Uh, whereas the periacoductal gray and the bed nucleus of the stria terminalis are parts of our brain that are supposed to help us decide what affective state we're going to be in. So, what this means is that where there should have been recruitment of the executive network, and the executive network would normally attenuate a hyper-aroused state. Say things like, this is not as big of a threat as it feels like right now. The executive network is now relatively dissociated from things like our salience network. This just means that we're spending way too much time and resources trying to assign meaning and value to sensory information, both interoceptive and exteroceptive, instead of ignoring it like we should be. And so our sympathetic nervous system is not effectively managed, and we are hyper-reactive to the world. It's extremely vague. When you're thinking about dissociation, instead of thinking dissociation, think functional disconnection. A functional disconnection can happen because things have been over-attenuated, there's been too much forceful silencing of something, or functional disconnection can happen because there's not enough attenuation, and one part of the brain is preventing another part from uh doing its job, being called up. It can also happen because of various types of brain damage or because of seizures. And so it is functionally dissociated. Many of the types of dissociation that we can identify are things like depersonalization, derealization. We might be dissociated from our sense of time, dissociated from our sense of space. And some of these dissociative states are in fact desirable for certain people. There are whole religions in which you practice meditative techniques in order to dissolve your sense of self, in order to reach a meditative state where you can, with effort, intentionally induce dissociation from your self-identity. I would love feedback if you have it. I have a few ways that you can do that. You can go to YouTube and this episode will be dropped there, and there's a place to comment on the episode there if you want. Or you can go to psydactic.com and I have a form that you can fill out there. Or you can email me feedback to feedback at psychactic.com. That's feedback at psychactic.com. And I appreciate you taking the time to hang out with me today. And come back anytime. I am Dr. O'Leary, and this has been an episode of Psychactic.