To Prevent Vascular Dementia, Maintain Healthy Weight

Maintaining a healthy body weight may help reduce the risk of vascular dementia, according to a new study in The Journal of Clinical Endocrinology & Metabolism. Researchers found that a higher body mass index (BMI) appears to play a direct role in causing vascular dementia, with high blood pressure accounting for part of the increased risk.

Vascular dementia is caused by reduced blood flow to the brain. It is the second most common form of dementia. Alzheimer's disease is the most common. 

Obesity as Cause or Association

Obesity has long been linked to a higher risk of dementia.

To better understand whether high body weight is a cause of dementia or just associated with it, researchers analyzed data from over 500,000 people who developed dementia in Denmark and the United Kingdom.

They examined five carefully selected genetic variants known to affect body weight and seventy-nine genetic variants associated with BMI for additional confirmation.

They also tested whether blood pressure, cholesterol, triglycerides, blood sugar, and inflammation levels mediated the relationship between body weight and dementia.

They found that people with genetically higher BMI had a 54% to 98% increased risk of vascular-related dementia, depending on the analysis method. The higher the BMI, the higher the risk of vascular dementia. 

High blood pressure explained a substantial portion of this risk. Systolic blood pressure accounted for 18% and diastolic blood pressure for 25% of the effect. 

The genetic findings were consistent across different analysis methods and populations. 

The research indicates that obesity may affect brain health both directly and indirectly through its effects on the cardiovascular system.

Low BMI and Dementia Risk

In this study, both very low and very high BMI were associated with higher dementia risk. However, the low BMI association is likely due to “reverse causation,” when people in early stages of dementia lose weight before diagnosis.

Excess Body Weight Directly Causes Dementia

This study provides strong evidence that excess body weight directly causes vascular-related dementia, primarily by raising blood pressure. This is important because both obesity and high blood pressure are modifiable risk factors, meaning they can be prevented or treated.

Maintaining a healthy weight and controlling blood pressure, especially in midlife (ages 40 to 65), could be effective strategies for preventing dementia later in life.

Lead author Dr. Liv Tybjærg Nordestgaard said, “Dementia is a devastating disease that currently affects 50 million individuals worldwide. Unfortunately, treatment and prevention options are scarce. Our study highlights the potential for reducing vascular-related dementia risk by addressing high BMI and/or high blood pressure in the population.”

What's Good for Your Heart is Good for Your Brain

Managing weight and blood pressure through diet, exercise, and medication may help protect against dementia as well as heart disease. Managing cardiovascular risk factors like high blood pressure, obesity, high cholesterol, and diabetes may help prevent diseases of cognitive decline.

What is Vascular Dementia?

Vascular dementia is a type of dementia caused by reduced blood flow to the brain. Just as the heart needs a constant supply of oxygen-rich blood to function, so does the brain. When blood vessels in the brain become blocked, narrowed, or damaged, parts of the brain don't get enough oxygen and nutrients. The lack of blood flow damages and eventually kills brain cells. 

Strokes cut off blood flow to part of the brain suddenly. They can be so small they go unnoticed but nonetheless damage is occurring. Damage to tiny blood vessels deep in the brain can be caused by cholesterol, smoking, diabetes, and genetic disorders to name a few. 

Over time, these injuries accumulate and cause the brain to atrophy and shrink,  leading to problems with thinking, memory, and daily functioning.

Vascular Dementia vs. Alzheimer's disease

Alzheimer's disease is caused by abnormal protein deposits in the brain while vascular dementia is caused by blood vessel problems. Both can occur together as a “mixed dementia.”