9-minute read time. Hello, all! It’s been a while since I last visited here. With a multitude of classes, a fantastic internship with Physicians for Human Rights, and a part-time job, it’s been challenging to make time for daily posts. Instead, I’ll be content with uploading some of the articles I’ve written for classes over the past few months. Here is a first draft about brain structures (that will likely later be edited), written for my Science in Action class.
Welcome to the Tour; Examining the Structures of a Hoarder’s Brain
Understanding the key structures in a hoarder’s brain, and how they might differ from a neurotypical brain, may be the first step to fight stigma and promote acceptance of hoarding disorder.
On a damp Monday in Baltimore, I find myself boarding a bright yellow school bus with wings and circular windows parked on the edge of a neuroscientist’s imagination. Our tour guide for the day is Ms. Frizzle, pulled-back red hair frizzing like static, wearing a dress patterned with MRIs and squishy pink brains. She grins at the crowd and shouts, “To the brain!”
Except, this isn’t a children’s cartoon. It’s a metaphor. And I’m not actually on a bus – I’m having a conversation with psychiatrist Marco Grados, M.D., and epidemiologist Jack Samuels, Ph.D., of the Johns Hopkins OCD Clinic. As they walk me through the neurological quirks of people who hoard, the metaphor takes hold. The brain, they explain, is not simply cluttered or damaged, it’s wired in a different way.
Hoarding disorder affects an estimated 2 to 6 percent of the population, according to Harvard Health and the International OCD Foundation, but its roots remain tangled in emotional, behavioral, and neurological complexity. There are an estimated 12 million hoarders in the United States, according to a study by Johns Hopkins University. Once classified as a subtype of obsessive-compulsive disorder, it is now a distinct diagnosis in the DSM-5, nestled under the heading, “OCD related disorders”. What sets it apart isn’t just the visible mess, but the invisible neural struggle behind every decision to discard, or not discard, something.
“Hoarding was considered a part of obsessive-compulsive for years. Now they consider it a separate entity, because there are people that can have hoarding without obsessive compulsive,” says Samuels. “We found that about 30% of people with OCD have hoarding symptoms. The main part of the brain in OCD is the anterior cingulate.”
Thus, our first stop on the tour: the anterior cingulate cortex, or ACC. This structure, nestled between the hemispheres of the brain like a neural zipper, plays a major role in decision-making, conflict monitoring, motivation regulation, and error detection. In people with hoarding disorder there is hyperactivity in the ACC when they’re asked to make decisions about their possessions.
Picture a person holding an empty jam jar. To most of us, it’s trash. To someone with hoarding disorder, it’s a tangled thought loop: What if I need this later? What if it could be repurposed? What if throwing it away is a mistake?
Neuroimaging studies confirm this hesitation. The ACC, which should briefly light up and then move on, stays stuck in high gear—as if the brain is constantly screaming, “Warning! Bad choice!”
“The anterior cingulate and the insula are key parts of the brain in OCD [and hoarding disorder],” says Grados. “The insula in particular has caught a lot of attention in recent years.”
Next, we descend into the insula, or the insular cortex, the “mushroom-shaped island behind the temporal and frontal lobes,” according to Grados. It’s a tucked-away region near the temples that helps process internal bodily sensations, emotional processing, and interoception, or the sense of our body’s internal state. In plain English: the insula helps us “feel” feelings, especially when they involve disgust or empathy.
“The insula has been associated with how your body feels internally,” says Grados. “Now it’s associated with anxiety, and with feelings rather than emotions. It’s also associated with conscience, like feeling guilty or not guilty.”
To a hoarder, throwing away an object doesn’t feel like tidying up. Instead, it can feel like betrayal, grief, even physical pain. A crumpled receipt can summon a wave of sadness. A broken stapler might evoke a sense of personal failure. The insula lights up, amplifying ordinary objects into emotional landmines.
As the bus bumps along, we approach the dorsolateral prefrontal cortex (DLPFC) and the ventromedial prefrontal cortex (vmPFC), two hubs for executive dysfunction, cognitive flexibility, assigning value, evaluating reward, decision-making, impulse control, social behavior, and emotional regulation. This region helps most people assess what’s worth keeping—what has meaning, utility, or sentimental value. But in hoarders, these areas appears to have their own priorities.
Here, the cognitive distortion becomes clear: A rusted keychain isn’t just an object; it’s a connection to the past, a symbol of control, a story not yet told. Discarding it feels like erasing part of the self. In a 2012 study published in Archives of General Psychiatry, researchers found that hoarders showed significantly higher vmPFC activation when making decisions about their own possessions, compared to someone else’s. Their brains quite literally “lit up” with value.
The bus then takes a sharp turn, emergency lights flashing, as we enter the amygdala. Known for its role in emotional significance and fear conditioning, this almond-shaped structure is the source of the brain’s fight-or-flight alarm system.
In this part of the brain, a missing coffee mug can trigger the same circuitry that might activate during a breakup or a robbery. The danger isn’t real, but the feeling is. Even exposure therapy—gradually discarding items—can provoke panic attacks in extreme cases.
The bus sputters past the hippocampus, which is involved with memory processes and contextual associations, and the basal ganglia, involved with motor control and habitual behaviors, in this wildly unorganized tour before it comes to a stop at our final destination. Our final stop isn’t a single region, but a network—the default mode network (DMN). This circuit of brain areas activates during rest, daydreaming, and internal storytelling.
This is where creativity and executive dysfunction collide. The DMN encourages expansive thought, but in hoarding, it doesn’t always switch off. Instead, it wraps every object in possibility and narrative. That’s why it’s so hard to let go.
To the outside world, hoarding can look like laziness or stubbornness. But inside the brain, it’s a cascade of biological and emotional processes that reshape how objects are perceived. The tour itself seems unfinished – proof of a need for further research – but it’s a start to understanding and a step in the right direction to ending the culture of shame that circles around hoarding.
Part of understanding is knowing that there is a complex multitude of reasons why someone might develop or innately have this condition. The disorder often worsens with age. According to a study published in the American Journal of Geriatric psychiatry in 1998, 23 percent of patients with dementia also showed hoarding behavior. Many patients have co-occurring conditions—depression, anxiety, ADHD, OCD, autism, Tourette’s. Additionally, “in humans who have undergone difficulty trauma and have PTSD, there seems to be more hoarding,” says Grados.
“The reason behind hoarding is different for everyone, because for one person it could be biological, and another, it could be a response to trauma,” agrees Samuels.
And while there are treatments, including cognitive behavioral therapy and medication, the stigma remains. But by understanding the neurobiology, we move closer to empathy. We stop asking, “Why don’t they just clean up?” and start asking, “How can we help them make peace with their brain?”
As I step off my imaginary magic school bus and back into reality, I realize that I, too, have an old college T-shirt I can’t seem to throw away. It doesn’t “spark joy,” but it sparks something. A feeling, a past self, a neural loop that’s hard to break.
We all have clutter. Most people have some sort of hoarding behavior. For some, it’s just harder to let go: not for lack of willpower, but because their brain fights them every step of the way. While “hoarding behavior” can refer to the act of collecting and keeping excessive items, it’s not necessarily a disorder unless it causes significant distress or impairment in daily life, as defined in the DSM-5.
“You can have hoarding behavior, but technically to have hoarding disorder, you have to have functional impairment and associated extreme emotional distress,” says Samuels.
Their brain is built in a different way, chemically and physically distinguished from someone who doesn’t have hoarding disorder. Each person in the world is unique from the next, our brains proof of our marvelous evolution and self-preservation.
Maybe, just maybe, understanding that is the first step toward clearing a little space for societal acceptance.
Sources
- Hwang JP, Tsai SJ, Yang CH, Liu KM, Lirng JF. Hoarding behavior in dementia. A preliminary report. Am J Geriatr Psychiatry. 1998 Fall;6(4):285-9. PMID: 9793576.
- Harvard Health Publishing. “Hoarding: What to Know About This Mental Health Disorder.” Harvard Health, November 18, 2024. Accessed June 20, 2025. https://www.health.harvard.edu/mind-and-mood/hoarding-what-to-know-about-this-mental-health-disorder.
- International OCD Foundation. “Who Gets Hoarding Disorder?” International OCD Foundation – Hoarding (IOCDF), accessed June 20, 2025. https://hoarding.iocdf.org/about-hoarding/who
- Grados, Marco, Child psychiatrist, Johns Hopkins University. Zoom interview. 6/2/25. [email protected]
- Samuels JF, Bienvenu OJ, Grados MA, Cullen B, Riddle MA, Liang KY, Eaton WW, Nestadt G. Prevalence and correlates of hoarding behavior in a community-based sample. Behav Res Ther. 2008 Jul;46(7):836-44. doi: 10.1016/j.brat.2008.04.004. Epub 2008 Apr 13. PMID: 18495084; PMCID: PMC2483957.
- Samuels, J. F., Bienvenu, O. J., Pinto, A., Fyer, A. J., McCracken, J. T., Rauch, S. L., Murphy, D. L., Grados, M. A., Greenberg, B. D., Knowles, J. A., Piacentini, J., Cannistraro, P. A., Cullen, B., Riddle, M. A., Rasmussen, S. A., Pauls, D. L., Willour, V. L., Shugart, Y. Y., Liang, K. Y., … Nestadt, G. (2007). Hoarding in obsessive-compulsive disorder: Results from the OCD Collaborative Genetics Study. Behaviour Research and Therapy, 45(4), 673-686. https://doi.org/10.1016/j.brat.2006.05.008
- Samuels, Jack, Epidemiologist and project director, Johns Hopkins University. In-person interview. 6/5/25. [email protected] Phone: 443-904-3661.
- Spineanu, Eugenia. Hoarding Disorder: Pathophysiology, Treatment Modalities, and Functional Rehabilitation. 2024. ISBN 979‑8333038722. [Independent publisher].
- Substance Abuse and Mental Health Services Administration. Impact of the DSM-IV to DSM-5 Changes on the National Survey on Drug Use and Health [Internet]. Rockville (MD): Substance Abuse and Mental Health Services Administration (US); 2016 Jun. Table 3.29, DSM-5 Hoarding Disorder. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519704/table/ch3.t29/
- Tolin DF, Stevens MC, Villavicencio AL, Norberg MM, Calhoun VD, Frost RO, Steketee G, Rauch SL, Pearlson GD. Neural mechanisms of decision making in hoarding disorder. Arch Gen Psychiatry. 2012 Aug;69(8):832-41. doi: 10.1001/archgenpsychiatry.2011.1980. PMID: 22868937; PMCID: PMC3506167.
