The relationship between salt (sodium) intake and Alzheimer’s disease is complex and not fully understood, but recent authoritative research suggests that **low dietary sodium intake may be associated with faster cognitive decline and increased Alzheimer’s-related brain pathology**, particularly tau tangles, rather than high sodium intake being clearly harmful in this context.
A large, well-conducted longitudinal study involving 1,520 older adults (average age about 81) found that those with the lowest sodium intake (around 1,764 mg/day) experienced a faster decline in global cognition, especially in episodic and semantic memory, compared to those with moderate sodium intake (about 2,264 mg/day). Importantly, the highest sodium intake group (around 2,800 mg/day) did not show this accelerated decline. Postmortem brain analyses of 717 participants revealed that low sodium intake was linked to a higher density of tau tangles, a hallmark of Alzheimer’s disease, but not to amyloid plaques or infarcts (areas of dead tissue due to lack of blood flow) [1].
This finding challenges the common assumption that lower salt intake is always better for brain health in older adults. It suggests that sodium may play a role in maintaining cognitive function and that insufficient sodium could contribute to neurodegenerative changes. The exact mechanisms are not fully clear, but sodium is essential for nerve function and cellular processes in the brain.
Other research indicates that **high sodium levels might influence tau protein changes**, which are involved in the formation of neurofibrillary tangles in Alzheimer’s disease. However, this evidence is less direct and more preliminary, highlighting the need for further study to clarify how sodium impacts tau pathology and overall brain health [2].
It is important to note that excessive sodium intake is well-established as a risk factor for cardiovascular diseases such as hypertension, stroke, and heart disease, which themselves can increase the risk of vascular dementia and possibly contribute to Alzheimer’s disease progression indirectly. High sodium intake is linked to increased cardiovascular mortality and stroke risk in large population studies [5]. Since cardiovascular health is closely tied to brain health, managing sodium intake remains important for overall health.
Dietary patterns that support brain health generally emphasize balanced nutrition rather than extreme restriction of any single nutrient. Diets like the Mediterranean or MIND diet, which are rich in healthy fats, fruits, vegetables, whole grains, and low in processed foods and excessive salt, have been associated with reduced risk of cognitive decline and Alzheimer’s disease [7][8].
In animal models, diets high in unhealthy fats and associated inflammation can worsen Alzheimer’s pathology through systemic inflammation and activation of brain immune cells (microglia), but these studies focus more on fat and inflammatory cytokines than sodium specifically [4].
In summary, while high sodium intake is a known cardiovascular risk factor, **very low sodium intake may be detrimental to cognitive health and linked to increased Alzheimer’s tau pathology**. Maintaining a moderate sodium intake as part of a balanced diet appears prudent, especially in older adults. More research is needed to define optimal sodium levels for brain health and to understand the biological mechanisms involved.
Sources:
[1] PubMed – Association of dietary sodium intake with late-life cognitive decline and neuropathology (2025)
[2] Doral Health & Wellness – Dementia and brain health: the role of key minerals
[4] Frontiers in Aging Neuroscience – Western diet-induced inflammation promotes Alzheimer’s pathology (2025)
[5] Nature – High sodium intake increases cardiovascular mortality and stroke risk
[7] PMC – Validation of MIND diet screener and Alzheimer’s risk (2025)
[8] Alzheimer’s Research UK – Healthy alternatives for better brain health
