Diets high in salt may cause dementia

Latest study on mice suggests a high-salt diet directly influences the blood flow to the brain, leading to impaired cognitive functions

During the research, mice groups were administered diets containing 4% or 8% salt, translating to 8 times or 16 times more than what a normal human diet consists in.

After 2 months, the mice were studied by using MRI analysis. As a result, scientists observed that the resting cerebral blood flow was considerably reduced, while learning and memory suddenly decreased. The cortex was reduced by 28 per cent, and the hippo-campus by 25 per cent.

“We discovered that mice fed a high-salt diet developed dementia even when blood pressure did not rise. This was surprising since, in humans, the deleterious effects of salt on cognition were attributed to hypertension,” explained study’s lead author Dr. Costantino Iadecola from Weill Cornell Medicine.

The mice that consumed exclusively the high-salt diet developed dementia. Moreover, they also developed an adaptive immune response, with an intense activity of white blood cells called T helper lymphocytes (TH17).

On the other hand, the effects of the high salt diet are reversible, as shown by the researchers when returning the diets to normal for four weeks. Consequently, cerebral blood flow and endothelial function went back to their normal limits.

“It appears to counteract the cerebrovascular and cognitive effects of a high-salt diet, and it also may benefit people with diseases and conditions associated with elevated IL-17 levels, such as multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease and other autoimmune diseases,” added study first author Dr. Giuseppe Faraco, from the same institute.

The study was published in the Nature Neuroscience Journal.