Sugar May Drive Dementia, German Medical Societies Warn

On World Brain Day (July 22, 2024), the German Society of Neurology (DGN) and the German Brain Foundation pointed out that too much sugar can harm the brain. The current results of the Global Burden of Diseases study shows that stroke and dementia are among the top 10 causes of death. A healthy, active lifestyle with sufficient exercise and sleep, along with the avoidance of harmful substances like alcohol, nicotine, or excessive sugar, protects the brain.

“Of course, the dose makes the poison as the brain, being the body’s powerhouse, needs glucose to function,” said Dr Frank Erbguth, president of the German Brain Foundation, in a press release from DGN and the German Brain Foundation. “However, with a permanent increase in blood sugar levels due to too many, too lavish meals and constant snacking on the side, we overload the system and fuel the development of neurologic diseases, particularly dementia and stroke.”

The per capita consumption of sugar was 33.2 kg in 2021/2022, which is almost twice the recommended amount. The German Nutrition Society recommends that no more than 10% of energy come from sugar. With a goal of 2000 kilocalories, that’s 50 g per day, or 18 kg per year. This total includes not only added sugar but also naturally occurring sugar, such as in fruits, honey, or juices.

What’s the Mechanism?

High blood sugar levels damage brain blood vessels and promote deposits on the vessel walls, thus reducing blood flow and nutrient supply to brain cells. This process can cause various limitations, as well as vascular dementia.

In Germany, around 250,000 people are diagnosed with dementia annually, and 15%-25% have vascular dementia. That proportion represents between 40,000 and 60,000 new cases each year.

In addition, glycosaminoglycans, which are complex sugar molecules, can directly impair cognition. They affect the function of synapses between nerve cells and, thus, affect neuronal plasticity. Experimental data presented at the 2023 American Chemical Society Congress have shown this phenomenon.

Twenty years ago, a study provided evidence that a diet high in fat and sugar disrupts neuronal plasticity and can impair the function of the hippocampus in the long term. A recent meta-analysis confirms these findings: Although mental performance improves at 2-12 hours after sugar consumption, sustained sugar intake can permanently damage cognitive function.

Diabetes mellitus can indirectly cause brain damage. Since the 1990s, it has been known that patients with type 2 diabetes have a significantly higher risk for dementia. It is suspected that glucose metabolism is also disrupted in neurons, thus contributing to the development of Alzheimer’s disease. Insulin also plays a role in the formation of Alzheimer’s plaques.

The Max Planck Institute for Metabolism Research demonstrated last year that regular consumption of high-sugar and high-fat foods can change the brain. This leads to an increased craving for high-sugar and high-fat foods, which in turn promotes the development of obesity and type 2 diabetes.

Reduce Sugar Consumption

DGN and the German Brain Foundation advise minimizing sugar consumption. This process is often challenging, as even a small dose of sugar can trigger the gut to send signals to the brain via the vagus nerve, thus causing a strong craving for more sugar. “This could be the reason why some people quickly eat a whole chocolate bar after just one piece,” said Erbguth. In addition, dopamine, a “feel-good hormone,” is released in the brain when consuming sugar, thus leading to a desire for more.

“It is wise to break free from this cycle by largely avoiding sugar,” said Dr Peter Berlit, secretary general and spokesperson for DGN. “The effort is worth it, as 40% of all dementia cases and 90% of all strokes are preventable, with many of them linked to industrial sugar,” said Berlit. DGN and the German Brain Foundation support the call for a tax on particularly sugary beverages. They also point out that foods like yogurt or tomato ketchup contain sugar, and alcohol can also significantly raise blood sugar levels.

This story was translated from the Medscape German edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.