A common laxative might help people recovering from depression with their "brain fog." This fog includes problems with memory, attention, and how quickly they process thoughts. These issues can last long after the mood symptoms of depression improve.
Currently, there are no specific treatments for these cognitive problems. However, new research suggests an existing drug could offer a solution.
How a Constipation Drug Helps Brain Fog
Researchers from the University of Birmingham and the University of Oxford studied prucalopride. This drug is approved for chronic constipation. They found it improved memory, attention, and executive function in people who had experienced depression.
We're a new kind of news feed.
Regular news is designed to drain you. We're a non-profit built to restore you. Every story we publish is scored for impact, progress, and hope.
Start Your News DetoxPrucalopride works by activating the serotonin 5-HT4 receptor. This receptor is found in both the gut and the brain.
The study involved 50 people who had a history of depression. They were given either 2mg of prucalopride or a placebo for seven to ten days. This 2mg dose is the same one used for chronic constipation.
Before and after the treatment, participants took cognitive tests. These tests measured executive function, short-term memory, long-term memory, and emotional cognition. Those who took prucalopride performed faster and more accurately on these tests.
Dr. Angharad de Cates from the University of Birmingham noted that brain fog is a significant but often overlooked part of depression. It can continue even when mood gets better. She said their study suggests that drugs targeting the serotonin 5-HT4 receptor, like prucalopride, could improve cognitive function in people with a history of depression.
Repurposing Drugs for Mental Health
These findings support more research into using 5-HT4-targeting medications for depression. They could also lead to new drugs for depression and other mental health conditions.
The study included adults aged 18 to 40 who had two past episodes of depression. All participants had recovered from a depressive episode at least six months before the trial. None were taking medication during the study.
Participants taking prucalopride received 2mg for five to eight days. The trial found no significant side effects. Dr. de Cates mentioned that participants did not have serious gut issues. Prucalopride works as a gentle laxative.
The cognitive tests included:
- An auditory verbal learning and memory task (AVLT) for declarative memory.
- A working memory task (N-back).
- Tests for executive functioning, attention, and processing speed (TMT, DSST).
The study also looked at three emotional cognition tasks.
On the "cold" cognitive tasks, which measure memory and executive function, participants on prucalopride showed higher accuracy and faster response times compared to those on placebo.
Professor Susannah Murphy from the University of Oxford said that for many, recovery from depression is incomplete due to lasting memory and concentration issues. She added that this study offers early evidence that 5-HT4 receptor agonists could help restore cognitive function. This opens an exciting new path for treatment development.
The research team continues to explore ways to treat cognitive problems linked to major depressive disorders. These problems can affect short-term memory, long-term memory, attention, and focus. Previous studies have also hinted that 5HT4 receptor agonists might lower the risk of depression.
Deep Dive & References
Pro-cognitive effects of 5-HT4 receptor agonism in individuals with remitted depression - Psychological Medicine, 2026
The National Institute for Health and Care Research (NIHR) Biomedical Research Centre: Oxford Health supported this work.
