Quieting the noisy brain: The Default Mode Network and mental disorders

Driving one my sons to soccer recently, I came to the stoplight just a mile or so from the practice field. As we waited for the light to change so that I could make my turn, my son called excitedly from the backseat, “Wow, they’re almost done!” 

“Almost done with what?” I called back, looking at him in the rearview mirror. 

He pointed straight ahead of us at what had been, for as long as I could remember driving this route, a large expanse of grass. “The huge building,” he said, with a touch more duh in his voice than I appreciated.  

My eyes shifted to the open field, or what was the open field before it magically became this monstrosity of a structure that sat before me. There were cranes and concrete mixers and a variety of other construction vehicles straight out of my kids’ favorite books, all surrounding a building I swore I had never seen before. 

“Whoa,” my eyes widened. “How long has that been there?” 

“Mom, did you seriously not notice that they’ve been building that?” my son asked in genuine surprise, which was warranted given that we drove this route at least three times every week and had done so for months. I guess not, I thought. 

I thought back to all the times his dad would ask the same question. No matter how long we’d been together, he would still react in wonder that I could appear so oblivious about a billboard we passed every day or the rotting branches on the tree across the street.

“I really don’t know,” I used to tell him when he’d ask how it was possible. And then I’d usually cite the to-do list that I was running through in my head for the hundredth time or the email replies I was constructing. Or, I’d say, I was thinking about what Lindsey said to me the other day and trying to figure out how she really meant it. Or where we should go on vacation next summer or whether I was really a good person or whether I wanted to choose the music for my own funeral or leave it to chance. 

“I’m neurotic, I know,” I’d admit as he’d raise his eyebrows and shake his head.

“Your mind, man. It doesn’t stop.” 

“Tell me about it,” I’d say. 

I’d been aware of how in my own head I could be for as long as I could remember. Of course I was aware. Too aware, perhaps. 

My gravitation towards the internal world seemed so inherent to who I was that I didn’t separate this quality from myself at all. I was a deep thinker, I would have said. I can’t help but turn thoughts and ideas over and over in my mind. 

There were times in my life where this felt like it was serving me moderately well – like when I would be writing pieces like this one, where I needed to draw upon my memories, my consciousness of myself, and make connections between my own and others’ experiences. 

And then, of course, there were times where my internal chatter would be so persistent and loud that it seemed to drown out everything around me. I’d find myself in constant paralyzing loops of ruminative thoughts, my mind seemingly trying to convince itself that if it just kept swirling, it would get to wherever it was trying to go.

It didn’t, of course, and the content of my thoughts would ping pong from the present (Am I doing enough to give my life meaning?) to the past (Did I really make the right choice in leaving that job?) to the future (What do I need to do to get ready for the barbecue?). The thoughts would be loosely tied together in ways I couldn’t reconstruct if I tried, and by the end of the day I’d crash into my pillow, cognitively exhausted from thinking about what seemed like absolutely nothing important. 

I tended to call this pattern of scattered and non-stop thoughts anxiety, even when I didn’t necessarily feel afraid of something so much as felt like I had a really noisy brain. But anxiety seemed to be what all the other women around me with constant mental chatter labeled it. And, like them, it made it feel impossible to relax. 

That inability to relax also seemed to make me not a particularly patient or friendly person. I’d find myself snapping at people who certainly didn’t deserve it, and it was almost like I couldn’t stand that they were interrupting the internal conversation I was always having with myself – even if I was exhausted of that conversation. 

The constant irritability was what led me at various points to take SSRIs, medications used to treat depression and anxiety. For me, it wasn’t so much that I felt I was in a dark hole of despair; it was feeling that I couldn’t take the endless loops in my head, the content of which would often be self-doubting and self-critical. 

Quickly after starting them each time, I’d find myself calmer, more patient. I’d be able to tune in better to conversations and I felt less reactive. They seemed to make things feel more tolerable and I felt more effective. I’d be told, like most of us who have tried SSRIs, that I must have a chemical imbalance, and the medication helped to get that in check. That was good enough for me, and I was grateful for the noise to quiet down. 

– 

I first heard about the Default Mode Network at a time where I was debating whether to transition off of my SSRI. While I didn’t have concerns, physical or philosophical, about staying on it long term, it had been having a pretty rough impact on my sleep, and I was curious if it was time to make a change. 

I didn’t have a name or a way of explaining yet what had happened in the past when I’d gone off of these medicines, and so all I could really articulate is that I worried my brain would get really loud again. As I started to learn more about the DMN, I began to recognize that perhaps that chatter had a name. 

The first person to give it one was a neurologist named Marcus Raichle, who discovered the DMN in 2001. He was curious to see what happens in the brain in the space in between, the times where our attention is not actively engaged in a task or external stimulus. He and his colleagues looked at neuroimaging to see what the brain was like at rest. As it turned out, it’s not really at rest at all. In fact, Raichle discovered that our brains are humming along and engaged in internal processing – thinking about ourselves – until an external stimulus interrupts it. 

What Raichle could see was that there was a network of areas of the brain that were quite active when we were seemingly doing nothing, so active that this neural network used about 90% of the energy consumed by the brain. Further studies showed that the DMN was active not only during awake times where we weren’t externally focused, but during sleep and even light anesthesia as well. It only took a so-called break when we got engrossed in something. 

As I started to make sense of this for myself, I thought about how I was always looking for things to engross me – a story, a person, an Instagram reel – and that this made sense because actually focusing on something felt like a break from my overactive popcorn brain. Not to mention, the external things I’d focus on didn’t leave me feeling that same sense of pressure or self-criticism that getting caught in my spirals seemed to. 

What the researchers realized is that spending too much time inside made us not only distracted, but also too focused on things like our flaws, our regrets, and our fears. As such, they suspected that this interesting new network could likely help us understand mental disorders. Researchers began studying the functioning of the DMN in various conditions, like depression, ADHD, and PTSD, and looking for patterns. Their findings were stark and powerful. 

They quickly saw that the DMN was particularly active, over-active, in people with many of the most common mental disorders. In depression, for instance, we began to see that people suffering from depression were essentially stuck in the Default Mode. Because the DMN involves the parts of the brain that are largely responsible for emotions, memories, self-analysis, and fear, being stuck here means that our brains struggle to find their way out of vicious loops of these internally-focused processes. Not only is this emotionally painful, but it means that we can’t shift into the inverse of the DMN, the Executive Network. 

The Executive Network is the neural network that’s active when we are engaged with things outside of ourselves. It’s what we need turned on to interact and to get things done. If you’ve been in a significant depression or know someone who has, you can probably picture that almost paralysis feeling that keeps people from being able to make healthy choices for themselves or do the things that they on some level really want to do. That’s being stuck in the Default Mode Network. When our DMN is overactive, it affects our mood, our concentration, and our energy, the trifecta that often characterizes depression. 

As I recognized my own overactive DMN at work, I started to wonder why mine seemed so busy. Why was I prone to 63 different trains of thought in the shower, while my partner would say he thought about nothing? 

The research on how our DMN functioning comes to be is newer, but it’s shedding some important insights. As we’d expect, both genes and our environment can have an impact on the development of the DMN, and the most interesting results happen at the gene-environment intersection. Specifically, experiencing early childhood stress or trauma changes how a specific gene called the SLC6A4 is expressed. That gene has to do with serotonin reuptake and changes the functioning of the DMN. Said plainly, experiencing early trauma turns on a gene that makes your DMN more active. 

This might make sense in that growing up in a highly stressful environment makes it important to stay vigilant of ourselves. We become more highly self-aware and our brains wire us to stay focused on things like what has happened to us in the past so that we can try to avoid the same things happening again. Essentially, our brains think that they are doing us a favor by priming us to be ultra self-aware. When I need to make sure that I’m safe and secure, the construction of a new building or a random billboard is extraneous. 

– 

The natural question, of course, is whether we can make changes to an overactive DMN given that it can seem to cause us a lot of suffering. This is not to say that the DMN is bad. Far from it, in fact, as it is considered the brain’s most sophisticated level of functioning. The ability to self-reflect, recall detailed memories, and consider others’ feelings is pretty rad. But like anything else, it can get carried away. 

My own observation that my brain seemed less overactive while on SSRIs is consistent with what pharmacological researchers are finding, suggesting that one of antidepressants’ core mechanisms of action is through altering the DMN. While this might seem obvious, the realization that this is an important way SSRIs work has been novel and important to understanding the bigger picture of mental disorders. 

But antidepressants aren’t the only way we can regulate the connectivity of the DMN, and these other paths have me personally really intrigued. One of these paths is through certain types of meditation, like mindfulness meditation. By engaging in regular practice of sustained attention and detachment to thoughts, meditators actually experience changes both structurally and functionally to their brains. 

The other path that’s got my attention is through psychedelics. Psychedelic researchers have long been interested in understanding why their use can have such a profound impact on our mental health. Before the DMN concept, psychedelics were already showing tremendous promise in the treatment of depression, existential anxiety, and PTSD, but it wasn’t clear how or why people would experience such significant changes. 

What we can now see is that psychedelics have a powerful suppression effect on the DMN. What that translates to is that a person who uses psychedelics has a quieting of the self-focused noise. Often people describe it as the very first time they’ve ever felt free from that inner critic and grounded enough to be able to make new connections.

In that space of freedom, people experience what has long been called a dissolution of the ego. For years that just sounded to most of us like a wacky new-age idea, but now we know that’s literally what’s happening. The DMN is what gives us the sense of difference between me and the rest of the world. When it’s suppressed, that distinction lessens. If that sounds scary, it’s usually not. Most people find that feeling less different from others and more connected to people and the world feels revelatory. They say things like, “I couldn’t understand why they would do that until now. I can now forgive and let go,” or, “I always say myself as so flawed or unworthy, but now I realize I’m not different from anyone else. I’m inherently good.” 

As you might expect, there’re plenty more to study on all of these pathways to regulating the DMN. But understanding it as a target for addressing mental health conditions and distress has been revolutionary. 

– 

My own history and biology seems to predispose me to a pretty active DMN, and I’m learning to both live with that truth and to practice shifting its balance. Even knowing that it’s what’s at play has had a positive impact on how I relate to my own thoughts and feelings. Instead of getting critical of my own restless mind, I can name what’s happening and respond with greater compassion. 

I’ve also found that letting my children be my models has helped to practice regulating my DMN. Children are still in the process of developing this neural network, which is why they tend to be more externally focused, at least ones that are growing up in relatively safe and stable environments. While their lack of self-awareness can sometimes seem mind-boggling, the flip side of that is their curiosity and wonder. 

Actively seeking wonder has been one of the ways I’ve been working on this myself, and for me that’s looked like searching for beauty, practicing a beginner’s mind, and trying out novel things that keep my attention engaged. It’s all taking effort, but it’s working. 

When my son pointed out the deer running through our yard the other morning, I could tell him honestly that I’ve seen them every day.

Get your free Mental Wellness Self-Assessment

For guidance, inspiration, and the scoop on our goings on, join our community list. You'll also get your "Mental Wellness Self-Assessment (+ Our Top Five Tools to Up Your Mental Health Game)" in your inbox right away.