In a first-of-its-kind study, researchers from Fujita Health University in Japan found that chronic low sodium levels can alter brain chemistry and lead to anxiety-like behavior in mice. The study offers a deeper look at how electrolyte imbalances might affect mental health and why sodium matters for more than hydration.
Low blood sodium, known medically as hyponatremia, is often considered a symptomless side effect of chronic illness or medication. But researchers found that in mice, sustained low sodium levels disrupted serotonin and dopamine balance in the brain's amygdala, the region tied to fear and emotion. The mice also showed more anxiety-like behavior in standard lab tests.
“This shows not only that chronic hyponatremia causes anxiety-like symptoms but also that these symptoms can be alleviated with proper correction of sodium imbalance,” said study co-author Dr. Haruki Fujisawa.
The findings could have implications for older adults and people with chronic conditions, who are more likely to develop hyponatremia due to medications or illnesses such as heart failure or SIAD (Syndrome of Inappropriate Antidiuresis). According to lead researcher Professor Yoshihisa Sugimura, these results highlight a need to recognize low sodium not just as a lab value, but as a potential contributor to mental health symptoms.
The study was published in Molecular Neurobiology and was supported by several Japanese research foundations, including JSPS KAKENHI, the Salt Science Research Foundation and the Yokoyama Foundation for Clinical Pharmacology.
This research was done in mice, and more work is needed to confirm similar effects in humans. But it adds weight to growing evidence that what’s happening in our bodies — including our salt balance — can directly impact the brain.