A New Threat of Excess Weight for the Brain Discovered

Scientists have proven: excess weight directly leads to vascular dementia through increased blood pressure

The relationship between excess weight and cognitive decline has long been a subject of scientific debate. Contradictory data from observational studies confused the picture: some indicated an increased risk of dementia in overweight middle-aged people, while others found a supposed "protective effect" of high body mass in the elderly. Researchers discovered that this paradox is explained by reverse causality – in the early stages of dementia, people often lose weight, which distorts statistical results.

To definitively determine the true cause-and-effect relationship, an international group of scientists applied the method of Mendelian randomization. This approach analyzes inherited genetic variants that affect body mass index, allowing researchers to establish a causal role rather than just correlation.

The large-scale study, published in The Journal of Clinical Endocrinology & Metabolism, covered more than 120,000 participants from Danish population projects and about 380,000 people from the UK Biobank. In conventional analysis, a classic U-shaped relationship was observed: an increased risk of dementia was noted both in people with insufficient weight and obesity.

However, genetic analysis revealed a completely different picture. It turned out that the higher the genetically determined body mass index, the higher the risk of developing vascular dementia – without any "protective" effect of excess weight that was mentioned earlier.

According to the researchers' calculations, an increase in genetically predicted BMI by one standard value increased the probability of vascular dementia by approximately 60%. In-depth analysis revealed that elevated blood pressure was the main mechanism of this influence. Both systolic and diastolic pressure explained a significant part of the negative impact of excess weight on dementia risk, while cholesterol levels, blood sugar, and inflammatory markers played a secondary role.

Vascular dementia develops as a result of chronic disruption of blood supply to the brain, often after a series of mini-strokes. Elevated pressure damages blood vessels, depriving neurons of necessary oxygen and nutrients. The new study convincingly proves that obesity, through increased pressure, triggers this destructive cascade of changes.

Scientists emphasize the importance of practical application of the obtained results. Control of body weight and blood pressure are not just general recommendations for maintaining health, but real and still underutilized tools for preventing dementia. Since effective methods for treating already developed disease practically do not exist, early prevention may be the key to solving the problem.