Every few months a headline promises that a new discovery "could halt dementia." If you're caring for someone with memory loss, or worried about your own, it's natural to read those stories with a mix of hope and caution.
In 2024, one of those stories was about leptin, a hormone best known for its role in appetite. Researchers at the University of Dundee in Scotland reported that small pieces of leptin could block some of the damage caused by two proteins linked to Alzheimer's disease.
This article explains what leptin is, what the Dundee team actually found, what larger studies in people have shown, and why it's likely to be years before any of this reaches a pharmacy.
What is leptin?
Leptin is a hormone made mainly by fat cells. Its best-known job is telling the brain how much energy the body has stored, which helps regulate appetite and weight.
Leptin also acts in parts of the brain involved in memory, including the hippocampus. Scientists have studied it for years because of its effects on synapses, the tiny connections between brain cells that let them communicate.
Why amyloid and tau matter
Alzheimer's disease is marked by the build-up of two proteins in the brain. Amyloid beta forms plaques between brain cells. Tau forms tangles inside them.
In the early stages of the disease, before large numbers of brain cells are lost, these proteins are thought to disrupt synapses. That early synaptic damage is linked to the first memory problems people notice. Protecting synapses has therefore become an important target for new treatments.
What the Dundee researchers found
Professor Jenni Harvey's team at the University of Dundee has studied leptin and synapses for many years. In a May 2024 university announcement, the team said its work shows leptin can block the ability of amyloid and tau to interfere with synapses in the lab.
The team also reported finding six-amino-acid fragments, out of the 167 amino acids that make up leptin, that keep this protective effect. Smaller molecules like these could be easier to turn into a drug, and the team has used them to design a potential drug template.
The work behind the announcement was published in the Journal of Neurochemistry. One study, on leptin-based hexamers, found these fragments helped memory and prevented amyloid-driven damage at synapses in laboratory models. A second study found that leptin prevents tau from moving to synapses, where it can impair how brain cells signal to each other.
Professor Harvey has described the findings as suggesting leptin could significantly slow, or even stop, the disease developing. That's an important hope for the research. But it's worth being clear about where the evidence stands.
Where the evidence stands
The Dundee findings come from laboratory work, including brain tissue and animal models. They have not yet been tested as a treatment in people.
That matters because most promising lab results don't make it through to approved medicines. A compound can work well in a dish or a mouse and still fail in human trials, because it doesn't reach the brain in large enough amounts, causes side effects, or simply behaves differently in people.
Professor Harvey herself has noted that many drugs fail because they can't cross the blood-brain barrier, which is one reason the team is focusing on small fragments.
So the honest summary is this: leptin is a promising line of research, and the Dundee work has produced a possible starting point for a drug. It is not a treatment yet, and there are no leptin-based medicines for Alzheimer's that people can take today.
What studies in people show
There's some supporting evidence from people, though it can't show cause and effect.
In 2009, a study from the long-running Framingham Heart Study looked at leptin levels in 785 older adults without dementia. Over a median follow-up of about eight years, people with higher leptin levels had a lower risk of developing dementia and Alzheimer's. Higher leptin was also linked to larger total brain volume on MRI scans.
This doesn't mean anyone should try to raise their leptin levels. Leptin is closely tied to body fat, and obesity in midlife is itself a risk factor for dementia. In a 2024 review, Professor Harvey noted that clinical studies suggest Alzheimer's risk rises when leptin levels fall outside the normal physiological range. In other words, the relationship is complicated, and more isn't simply better.
Why this research still matters
Even without a treatment, this kind of work helps. It adds to scientists' understanding of how Alzheimer's starts, and it points to synapses as a place where damage might be stopped early, before large numbers of brain cells are lost.
It also fits a broader shift in Alzheimer's research towards the earliest stages of the disease. Several approaches now focus on detecting changes sooner, and on treating people while their symptoms are still mild. Our article on AI-powered cognitive assessments and early detection covers some of the tools being developed to find those early changes.
What you can do now
While leptin research continues, there are things with stronger evidence that people can do today. The 2024 Lancet Commission on dementia estimated that nearly half of dementia cases might be prevented or delayed by addressing 14 modifiable risk factors across the life course.
Some practical steps include:
Stay physically active. Regular movement supports heart and brain health. Our article on why building muscle matters more than losing weight is a good place to start.
Look after your heart. Keep blood pressure, cholesterol and blood sugar in check with your doctor.
Eat well. Our article on whether diet can prevent dementia looks at what the latest science says.
Protect your hearing and vision. Get checked, and use hearing aids or glasses if you need them.
Stay connected and keep learning. Social contact and mental challenge both support brain health. Our article on neuroplasticity in older age explains why it's never too late.
For more on risk reduction, read our guide to whether dementia can be prevented or delayed.
Healthy routines only help if they happen day to day. Elli Cares supports older adults with gentle reminders for medications, appointments and daily habits, such as a walk or a glass of water, and a simple daily wellbeing check-in. Family members in the care circle can see how the day is going and add their own observations. See how Elli supports seniors and families.
How to read the next dementia headline
Research like this is genuinely exciting, and it's right to feel hopeful. But a few questions can help you judge any new "breakthrough" story:
Was it done in people, animals or cells? Early lab work is an important first step, but it's a long way from a treatment.
How many people were studied? Small studies are more likely to produce results that don't hold up.
Does it show cause, or just a link? Observational studies can find patterns but can't prove one thing causes another.
What do independent experts say? Organisations like the Alzheimer's Association and Alzheimer's Society often comment on major findings.
If you're worried about memory changes, the most useful step today is still a conversation with a doctor.
