For the 50 million families worldwide touched by Alzheimer's disease — including more than 60,000 people living with dementia in Scotland alone — any glimmer of hope is precious. Now, a decade-long investigation by Harvard Medical School may have uncovered one of the most promising leads in years: a humble element called lithium.
Professor Bruce Yankner and his team at Harvard have discovered that lithium isn't just a psychiatric medication — it occurs naturally in the brain and plays a vital role in keeping our neurons healthy. More remarkably, their research shows that lithium depletion is one of the very earliest changes detectable in people developing Alzheimer's.
"I try to provide hope," Yankner told the Harvard Gazette. And for once, the science may justify it.
How it works — in plain English
The Harvard team, whose findings were published in the journal Nature, analysed post-mortem brain tissue from hundreds of people across the cognitive spectrum — from healthy individuals to those with mild cognitive impairment and advanced Alzheimer's.
Of 27 metals examined, lithium was the only one significantly reduced in the brains of people with mild cognitive impairment (MCI) — the stage that often precedes Alzheimer's. The reason? Amyloid plaques — the sticky protein clumps that are a hallmark of the disease — appear to act like sponges, soaking up the brain's natural lithium supply and starving cells of an element they need to function.
Without adequate lithium, the brain's immune cells — called microglia — can no longer do their job of clearing away those damaging plaques. It's a vicious cycle: plaques trap lithium, and low lithium allows more plaques to form.
When researchers replicated this lithium depletion in mice, the results were stark. Animals developed more amyloid plaques, more tangled tau protein, and suffered significant memory loss.
The lithium orotate twist
Here's where it gets interesting. The team tested 16 different lithium compounds to find one that could evade the amyloid trap. Lithium carbonate — the form prescribed for bipolar disorder — gets bound by plaques just like the brain's natural lithium. But a compound called lithium orotate slipped through.
At doses one-thousandth of the clinical amount used for mood disorders, lithium orotate reversed memory loss, reduced plaque build-up, and restored synaptic connections in mouse models — without toxic side effects.
"My hope is that if lithium worked out, it might actually restore function, not only change the slope of decline," Yankner told PBS News. "So I'm optimistic, but we have to hold judgment until we see what happens in people."
What happens next
Yankner's team is now collaborating with researchers at Massachusetts General Hospital and Brigham and Women's Hospital on a clinical trial of lithium orotate in human patients, expected to begin this spring.
This matters because current Alzheimer's treatments — the antiamyloid antibodies lecanemab and donanemab — are expensive intravenous infusions with modest benefits at best. Lithium orotate, by contrast, is an inexpensive oral compound. However, experts strongly caution against self-prescribing ahead of trial results.
Dr Sara Imarisio, Head of Research at Alzheimer's Research UK, has highlighted the urgency of following up on lithium's potential. "There is a desperate need for new dementia treatments," she said. "Where there is evidence that an existing, widely used, relatively safe and inexpensive drug could help, it is vital that researchers follow up on this as quickly as possible."
A Scottish perspective
In Scotland, where more than 60,000 people are living with a dementia diagnosis according to Public Health Scotland's latest figures, the stakes are deeply personal. The Alzheimer Scotland Dementia Research Centre at the University of Edinburgh continues to support world-class research into the disease, and the charity's 24-hour helpline (0808 808 3000) remains a lifeline for families navigating the condition.
Rachel Whitmer, Professor of Neurology at UC Davis, urged patience alongside optimism. "How you translate [mouse experiments] to humans is more complicated and takes longer," she said, "but with the right planning, it can absolutely happen and it can absolutely be successful."
For the millions waiting, that careful optimism may be exactly what's needed. The marathon, as Yankner — himself a former long-distance runner — would say, continues. But the finish line, for the first time in years, feels a little closer.
