"Lithium deficiency is … a potential common mechanism for the … degeneration of the brain that leads to the onset of Alzheimer's disease."
That's the conclusion from a groundbreaking study published in the journal Nature [1]. Alzheimer's disease is one of the leading causes of death, but its exact drivers remain uncertain. This research points to a possible new mechanism — one that raises the potential for a novel way to both detect and address this debilitating condition.
Below is an evidence-based breakdown of the study and what the broader research landscape says about low-dose lithium and cognitive health.
Table of Contents
The New Study
Researchers already have a decent grasp of the process of brain decay that happens with Alzheimer's disease. It involves two basic mechanisms. First, there's the buildup of sticky protein fragments called amyloid plaques, which form outside brain cells and disrupt communication. Second, there are twisted tangles of a protein called tau that build up inside neurons, disrupting normal function. Together, these problems trigger inflammation and, eventually, cell death.
What is less well understood is why this process happens and what can stop it. Scientists have identified some genetic variations that increase individual risk of developing Alzheimer's. But environmental factors remain poorly characterised [1].
These environmental factors are obviously crucial — because while genes cannot be changed, steps can be taken to modify the environment once risk factors are identified.
Researchers have identified several environmental factors that seem to play a role in Alzheimer's disease. One of these is the levels of metals in the brain [1]. Previous studies have mostly examined the toxic effects of excess iron or copper. But the disruption of normal levels of important metals has received comparatively little attention [1].
That's what researchers in this latest study set out to investigate — and they made a startling discovery.
Researchers examined human brain tissue samples from people who had died. The samples came from individuals with no cognitive impairment (NCI), mild cognitive impairment (MCI), and Alzheimer's disease (AD). They measured 27 different metals in these samples [1].
One metal stood out: lithium. Its levels were much lower in the brains of those with MCI or Alzheimer's disease [1].
Interestingly, blood lithium levels appeared normal in those with cognitive decline. So the problem was not systemic — it was localised in the brain [1].
Researchers had reason to suspect the amyloid plaques were involved, so they specifically examined lithium levels within these plaques. They found lithium was concentrated in the plaques, and the levels were even higher in those with Alzheimer's than those with mild cognitive impairment [1].
This suggested a plausible mechanism: the amyloid plaques absorb lithium, depleting it from surrounding brain tissue.
This led to an important question: is lithium deficiency a causal factor in Alzheimer's disease progression?
To find out, researchers turned to mice. They reduced lithium intake by 92% in the animals' diets. Some mice were genetically modified to develop plaques early. In these mice, plaques formed sooner and grew faster when lithium was restricted. Normal mice also showed increased levels of the proteins that form plaques when on the low-lithium diet [1].
Not only that, the low-lithium diet promoted tau tangles as well [1].
And the negative effects didn't stop there. The lithium-deficient mice also showed increased inflammation, microglial activation, loss of synapses, axons, and myelin, and cognitive decline [1].
This paints a picture of a vicious cycle: amyloid plaques absorb lithium, depleting it from the brain. That lithium deficiency, in turn, accelerates plaque formation and other Alzheimer's-related damage.
And here's the deeper mechanism: as plaques sequester lithium, this depletes lithium in healthy brain regions. That drop impairs microglial clearance of amyloid plaques — allowing more plaques to form. It's a classic positive feedback loop [1].
The Broader Context
The implications of this are significant. The researchers believe this could be a key mechanism that drives Alzheimer's disease. However, the study relied heavily on mouse models and extremely low dietary lithium, which might not reflect real-world scenarios — so caution is warranted in interpreting these findings.
Do human studies support this?
There is evidence going back decades that lithium affects cognitive function. High-dose lithium is a long-standing treatment for bipolar disorder. More recently, observational studies have linked lithium to cognitive benefits. A Danish population study of over 73,000 dementia patients and 733,000 controls found an inverse relationship between lithium in drinking water and dementia incidence [2].
Another study followed up with participants from an earlier clinical trial on lithium for mild cognitive impairment. Over a decade later, those who had taken lithium scored better on cognitive performance tests than those who hadn't [3].
What about clinical trials?
Two early trials found no cognitive improvement with lithium. However, this may have been because they used lithium carbonate, a form that — based on newer data — may be ineffective due to its high binding to amyloid plaques [1].
Three subsequent trials used lower serum concentrations (0.25–0.5 mEq l−1) and found that lithium reduced cognitive decline [1].
A meta-analysis comparing lithium and the Alzheimer's drug aducanumab found that lithium was significantly more effective at preventing cognitive decline [4].
Implications
All of this naturally raises the question: should people supplement with low-dose lithium? What are the risks, the benefits — and what form of lithium is best?
The original study offers some clues. Researchers noticed lithium becomes bound to amyloid plaques, limiting its availability to the brain. So they examined whether lithium orotate, a different form than the clinically-used lithium carbonate, might avoid being trapped in plaques.
They tested both forms in mice. Both forms raised blood lithium levels similarly. But in the brain, lithium carbonate led to high lithium levels within plaques, while lithium orotate increased lithium in healthy brain regions [4].
And this made a major difference. Lithium orotate almost completely blocked plaque formation and tau accumulation. Lithium carbonate had no significant effect [4].
Even more notably, lithium orotate significantly slowed disease progression, whereas lithium carbonate did not [4].
The form of lithium clearly matters. The researchers suggest this might explain why earlier trials using lithium carbonate failed — they were using a form that binds too readily to amyloid plaques [4].
So here is what the current evidence suggests:
- Lithium deficiency might be a key driver in the development of Alzheimer's.
- Increasing lithium intake — particularly with lithium orotate — might help slow or prevent disease progression.
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The form of lithium is crucial. Lithium orotate appears to be far more effective at reaching healthy brain tissue.
That sounds like a compelling case for low-dose lithium orotate. But several important caveats merit consideration before drawing firm conclusions.
Key caveats:
1. The research is still limited, especially in humans. While animal studies and some human data are promising, larger and longer trials are needed to draw firm conclusions.
2. The optimal dose for cognitive protection is not yet established. Too much lithium can have serious side effects, particularly at higher doses used in psychiatric treatment. While low-dose use is considered safer, risks still exist.
3. Dietary and water sources already contribute some lithium.
The Danish study was based on naturally occurring lithium in water supplies. One study also found that certain vegetables — such as bulbous vegetables and fructose solano vegetables — can have very high lithium concentrations [5].
- Bulbous vegetables: Li > 13.47 mg/kg
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Fructose solano vegetables: Li > 11.33 mg/kg
4. These levels were high enough to raise concerns about excessive intake from dietary sources alone.
People who live in areas with lithium-rich water or consume a lot of high-lithium foods may already be getting meaningful amounts from their diet. This variability makes it difficult to generalise supplementation recommendations at this stage.
The bottom line: better clinical evidence is needed before strong supplementation recommendations can be made. This remains an active and rapidly evolving area of research that warrants close attention.
