Brain lithium levels drop 60 percent in people with Alzheimer’s–sometimes years before symptoms appear, a Harvard study finds.
Before memory fades in Alzheimer’s disease, something else quietly vanishes: lithium.
A large, decades-long study shows that lithium, naturally obtained through diet, may be essential for brain health — with its deficiency potentially setting the stage for neurodegeneration.
Lithium is often linked to rechargeable batteries, but it has long been used in mood stabilizers and occurs naturally in foods.
“This is the first study to look at lithium deficiency and to show there’s natural lithium in the brain and it has a protective role,” senior researcher Dr. Bruce Yankner, a professor of genetics and neurology at Harvard Medical School, told The Epoch Times.
“We were surprised by how central lithium appears to be—it affected so many aspects of Alzheimer’s.”
In the recent study published in Nature, Yankner’s team found that lithium concentrations in the brain’s prefrontal cortex—central to memory and decision-making—drop by more than half in people with Alzheimer’s disease. This decline begins years earlier, during mild cognitive impairment, which often signals the onset of dementia.
Drawing on nearly 400 human brain samples and animal models, the researchers suggest lithium may act like a dietary micronutrient—akin to zinc or iron—helping the brain resist aging and disease. Its loss appears to coincide with, and possibly drive, many of the earliest changes seen in Alzheimer’s disease.
Restoring lithium to healthy levels, Yankner said, could become a way to prevent the disease before symptoms take hold.
How Much Lithium Are We Talking About?
Alzheimer’s disease, which affects more than 55 million people worldwide, is defined by the buildup of amyloid plaques and tau tangles—abnormal proteins that disrupt communication between brain cells. However, these changes alone don’t always lead to memory loss. Some people with amyloid and tau lesions never develop symptoms, while others decline rapidly.
To uncover chemical changes that might help explain this gap, Yankner’s team measured 27 elements in brain and blood samples from older adults—some cognitively healthy, others with mild cognitive impairment, and others diagnosed with Alzheimer’s disease.
Lithium stood out as the only element showing a sharp, early decline in both women and men with cognitive impairment.
In healthy adults, lithium levels in the prefrontal cortex were usually between about 0.5 and 10 nanograms per gram of tissue—just a billionths of a gram. This range indicates normal levels.
In people with mild cognitive impairment, levels were about one-third lower than healthy peers. Those with Alzheimer’s showed a steeper drop—nearly 60 percent lower than in peers who had no memory problems.
Notably, blood lithium levels remained stable across all groups, indicating that the deficiency specifically targets the brain.
“These findings were so striking we didn’t believe them at first,” Yankner said. “We validated the result across multiple brain banks before we were convinced.”
Other trace metals showed either inconsistent changes or appeared only in more advanced Alzheimer’s disease.
The research revealed why lithium levels drop: amyloid plaques—the sticky protein clumps central to Alzheimer’s—bind directly to lithium and trap it. Because lithium carries a positive charge, it sticks to the negatively charged plaques like a magnet, drawing it away from neurons and other brain cells that depend on it.
As amyloid accumulates, more lithium becomes locked away in plaques, creating a vicious cycle: the more plaques, the less lithium remains available to protect brain cells. This creates what Yanker called a “lithium deprivation state,” depriving neurons of a key resource for resilience and repair.
