Low sodium levels in the blood have been linked to declines in cognitive function among otherwise healthy older men in a new study, which has now been published in the Clinical Journal of the American Society of Nephrology.
The authors suggest that addressing these low sodium levels — which are known medically as hyponatremia — could be valuable in halting cognitive decline as people age.
Hyponatremia occurs when blood sodium levels fall below 135 millimoles per liter (mmol/L).
Medical News Today have previously reported the results of studies warning of the dangers of drinking too much fluid when exercising, as this can lead to exercise-associated hyponatremia (EAH).
Mild symptoms of EAH include dizziness, nausea, and puffiness, but more severe cases can be fatal. It is estimated that at least 14 athletes have died from EAH.
Severe cases of hyponatremia have previously been associated with neurological and cognitive problems, but studies have not pinpointed how different levels of sodium in the blood affect cognition in older adults.
The authors of the new study, from the University of Colorado Anschutz Medical Campus in Aurora, set out to investigate.
Risk of cognitive decline increased
The researchers behind the new study looked at data from 5,435 healthy men aged 65 and older, who were each followed for an average of 4.6 years.
The results show that men whose sodium levels were 126–140 mmol/L were 30 percent more likely to have symptoms of cognitive impairment at the start of the study and 37 percent more likely to experience symptoms of cognitive decline over time, compared with men with sodium levels of 141–142 mmol/L.
Interestingly, high sodium levels of 143–153 mmol/L were also associated with cognitive decline over time.
Lead study author Kristen Nowak, Ph.D., says that more studies are needed to further investigate what corrective action can be taken to prevent cognitive decline in people with hyponatremia.
She adds, "Slightly lower sodium levels in the blood are likely to be unnoticed in clinical practice."
"Because both slightly lower serum sodium levels and mild changes in cognitive function are common occurrences with advancing age, future research on this topic is important — including determining whether correcting lower sodium levels affects cognitive function."
Kristen Nowak, Ph.D.