LSD Treatment Affects Working Memory-Related Brain Function in Patients with Major Depressive Disorder

Bottom line: High-dose LSD was associated with increased brain activity in working memory-related regions in patients with major depressive disorder.

A 43-year-old woman named Anna sat in a chair, staring at a screen that flashed numbers and letters. Her hands trembled slightly, and her mind felt like a fog machine. She had been battling major depressive disorder for years, trying every medication and therapy that came along, but nothing had touched the way her thoughts felt sluggish and heavy. Then, in a clinical trial, she was given a single pill — a low dose of LSD. Her brain, once a labyrinth of static, began to hum with new patterns of activity. What she didn’t know was that her experience was part of a study that would change how we think about the brain, memory, and the promise of psychedelics in treating mental illness.

The Brain’s Hidden Engine

Working memory is the brain’s temporary storage system — the mental workspace where we hold and manipulate information to solve problems, make decisions, and navigate the world. It’s what lets you remember a phone number long enough to dial it, or follow a complex argument. In people with major depressive disorder (MDD), this system is often impaired. Studies show that patients struggle with tasks requiring sustained attention, rapid switching of thoughts, and even basic memory recall. But how much does the brain itself change in response to treatment, and can psychedelics — those strange, mind-bending substances — actually reshape it?

A study in Translational Psychiatry aimed to answer that question. Researchers at the University of Zurich and the University Hospital Zurich conducted a randomized, double-blind trial with 43 patients diagnosed with MDD. Each received two doses of LSD — one low (25 µg) and one high (100 and 200 µg) — spaced four weeks apart. Before and after each treatment, they performed a working memory task on an fMRI machine, where they had to press a button when a number appeared in a sequence, matching it to the one shown earlier. It’s a simple task, but one that requires precise neural coordination.

What they found was unexpected. Compared to low-dose LSD, the high-dose treatment significantly increased brain activity in regions associated with working memory, including the dorsolateral prefrontal cortex, parietal cortex, insula, striatum, and thalamus. These areas are part of the brain’s “executive network,” responsible for planning, decision-making, and integrating sensory information. The increase in activity wasn’t random — it was tied to how well participants performed the task and how vividly they described their psychedelic experience. But it didn’t seem to correlate with how much their depression symptoms improved.

The Surprising Link Between Psychedelics and Neural Plasticity

One of the most intriguing findings was that the brain’s response to high-dose LSD was not just about increased activity — it was about enhanced connectivity. The researchers used linear mixed effects models to analyze the data and found that certain brain regions, like the insula and the striatum, showed a stronger synchronization between them during the task. This kind of neural coupling is thought to underpin the sense of “flow” or “connectedness” people often report during a psychedelic experience.

But here’s the twist: this increased connectivity wasn’t linked to a reduction in depressive symptoms. In other words, the brain was working harder, but the person didn’t feel better. That’s not just a technical detail — it’s a clue that the mechanisms of depression and the mechanisms of psychedelic action might be fundamentally different. The brain’s ability to process information and the emotional state of the person are separate systems, and LSD seems to influence one without the other.

This finding is especially significant because it challenges the assumption that psychedelic treatments work by directly altering mood. Instead, it suggests that these substances might be acting more like a “reset” button for the brain’s cognitive architecture, temporarily enhancing its capacity to process information in ways that are normally suppressed in depression.

The Mystery of the Unrelated Correlation

The study also found that task performance — how well participants did on the working memory test — correlated with the intensity of their subjective psychedelic experience. If someone reported feeling more “connected” or “aware” during the treatment, they also performed better on the task. But this wasn’t connected to how much their depression symptoms improved. In other words, the brain was working better, but the person wasn’t feeling better.

This is a critical distinction. It implies that the neural changes induced by LSD are not necessarily tied to the emotional or cognitive improvements people often report. The brain’s activity patterns may be shifting, but the person’s experience of depression — their mood, their sense of self, their perception of the world — isn’t changing in a way that’s measurable through standard depression scales.

This raises an important question: if the brain is working better, but the person isn’t feeling better, what is the real target of psychedelic treatment? Is it the brain itself, or the emotional and psychological states that arise from it?

Frequently Asked Questions

Q: Can LSD actually improve working memory in people with depression?
A: Yes, the study found that high-dose LSD significantly increased working memory-related brain activity in patients with MDD. However, this increase in brain activity wasn’t linked to a reduction in depressive symptoms, suggesting that the effects on cognition and mood may be separate.

Q: Is this the first study to show LSD affects brain function in MDD?
A: Yes, this is the first study to provide evidence that LSD treatment in patients with MDD affects cognitive brain function, as measured by fMRI during a working memory task.

Q: How does LSD affect the brain differently than traditional antidepressants?
A: Traditional antidepressants like SSRIs typically work by altering neurotransmitter levels, which can take weeks to show effects. LSD, on the other hand, appears to influence brain connectivity and neural activity more rapidly, potentially by disrupting rigid neural patterns and promoting more flexible, adaptive brain function.

Q: Are the results of this study applicable to everyone with depression?
A: The study sample was relatively small, and the results may not apply to all individuals. Factors like genetics, past trauma, and personality traits can influence how someone responds to psychedelics, so further research is needed to determine the broader applicability of these findings.

Q: What are the next steps for this research?
A: The researchers suggest that future studies should explore the long-term effects of LSD on brain function and investigate whether the observed changes in neural activity translate into lasting improvements in cognitive or emotional well-being. They also emphasize the need to better understand the mechanisms behind the observed effects and how they might be harnessed for therapeutic purposes.

Sources

• ¶LSD treatment affects working memory-related brain function in patients with major depressive disorder
• ¶Treatment-Resistant Depression: A Literature Review of Innovative and Emerging Treatment Strategies
• ¶Health service access and delivery for people living with rare disorders: a scoping review

Educational Disclaimer

This article is for informational and educational purposes only. It is not medical advice, mental health advice, diagnosis, treatment guidance, or a recommendation to use any substance, supplement, therapy, or protocol.

We review publicly available research and explain what the evidence may suggest. Some studies may be early-stage, observational, animal-based, lab-based, theoretical, or incomplete. Always consult a qualified professional before making health-related decisions.

If you or someone you know is struggling, you are not alone. In the US, call or text 988 (Suicide & Crisis Lifeline). Elsewhere, contact your local emergency or crisis service.

Researched and drafted by Spore, ShroomWire’s AI research assistant, and reviewed by the ShroomWire editorial team before publishing.