A new study is giving scientists hope that a commonly prescribed type of antidepressant might do more than just help with mood. According to Neuroscience News, the drugs in question are selective serotonin reuptake inhibitors, better known as SSRIs. They’re one of the most frequently used treatments for depression and anxiety, but now researchers think they might also help tackle some of the biological signs of Alzheimer’s disease.
The study, led by a team at the University of California San Francisco, looked at 191 people diagnosed with Alzheimer’s. Some of them were taking SSRIs, and others weren’t. What stood out was that the patients on SSRIs showed lower levels of something called phosphorylated tau-181 in their blood. This substance—often just called p-tau—is closely linked to how severe Alzheimer’s is. In other words, people taking these antidepressants had less of one of the key proteins that builds up in the brains of people with the disease.
To understand why this matters, it helps to know a bit about how Alzheimer’s works.
Two major proteins are involved in the disease: amyloid and tau. These proteins start to clump up in the brain, disrupting communication between brain cells and eventually killing them off. While amyloid tends to get most of the attention in the media, tau is a big player when it comes to the progression of symptoms—especially memory loss and confusion.
One part of the brain the researchers paid close attention to is called the dorsal raphe nucleus, or DRN for short. It’s a small region deep in the brainstem, and it’s one of the first places Alzheimer’s-related tau tangles appear. It’s also a place that produces serotonin, the chemical that helps regulate mood. In healthy people, this area is active and working away, but in people with Alzheimer’s, it starts to shut down. This study found that people with Alzheimer’s who were on SSRIs had more activity in the DRN compared to those not on the medication. That’s a pretty big deal, because it suggests these antidepressants might help keep this vulnerable part of the brain functioning.
Interestingly, this effect wasn’t seen in the healthy control group—only those with Alzheimer’s seemed to show this type of metabolic activity in response to the medication. That hints at something more specific going on between SSRIs and the disease itself, rather than a general effect on the brain.
But here’s where it gets tricky.
Even though the biological markers looked promising—less p-tau in the blood, more activity in a critical brain region—the study didn’t find clear, across-the-board improvements in memory or thinking skills. Some patients taking SSRIs did show better scores on certain cognitive tests, but not all of them, and the results varied depending on which testing methods were used. That makes it hard to say with confidence whether these biological changes actually lead to noticeable improvements in day-to-day brain function.
The researchers are the first to admit this study isn’t the final word on the matter. It was a cross-sectional study, which means it took a snapshot in time rather than tracking changes over a long period. That makes it difficult to know whether the SSRIs caused the drop in p-tau, or if perhaps people who already had lower levels of it were more likely to be on antidepressants for some other reason.
Still, the findings are enough to encourage further investigation. Alzheimer’s is one of the most complex and devastating conditions we face, and so far, treatment options have been underwhelming. Most current drugs aim to slow down symptoms rather than stop or reverse the disease. If SSRIs—a class of drugs that’s been around for decades and is already widely prescribed—could play a role in protecting the brain, even in a small way, that would be a game-changer.
There’s also something reassuring in the idea of repurposing existing medications.
Developing new Alzheimer’s drugs from scratch is expensive, slow, and often unsuccessful. SSRIs, on the other hand, have already been studied for years, and doctors understand how they work and what side effects to look out for. If further trials support this new connection, it could mean a much faster route to a widely available, low-cost treatment option.
That said, scientists caution against seeing this as a miracle cure. Alzheimer’s affects different people in different ways, and a treatment that works well for one person might not do much for another. There’s also the fact that antidepressants can come with side effects, and they aren’t suitable for everyone—particularly older adults who might already be taking multiple medications.
The study’s lead author stressed that these findings are “hypothesis-generating,” not definitive proof. The next step would be to launch longer-term, controlled clinical trials that follow patients over months or years to see whether taking SSRIs consistently leads to slower progression of Alzheimer’s, fewer symptoms, or better quality of life.
In the meantime, this research is helping scientists think differently about the relationship between mood, brain chemistry, and neurodegenerative disease.
For years, it’s been clear that depression and Alzheimer’s are often linked—people with a history of depression are at a higher risk of developing Alzheimer’s, and people with Alzheimer’s often struggle with depression as their condition worsens. It’s possible that serotonin and the systems that regulate it could be a missing piece of the puzzle.
Ultimately, while we’re still in the early stages, this study adds to a growing sense of urgency around finding new angles to tackle Alzheimer’s. With populations ageing across the world and millions of families already affected, the need for more effective treatments couldn’t be more urgent. Whether SSRIs end up being part of the answer remains to be seen—but they’ve definitely earned a closer look.
For now, doctors and researchers are watching carefully. Patients and families dealing with Alzheimer’s should not change medications without speaking to a specialist, but they can be encouraged by the fact that science is exploring every possible lead—including the ones hiding in plain sight, like drugs already sitting in the medicine cabinet.