Keeping our minds sharp as we age is essential on many levels, from helping us preserve our independence to increasing longevity and quality of life. And since changes in the brain start decades before symptoms of dementia show up, it’s never too early to begin healthy brain habits.

Some of those habits might include keeping an eye on your blood pressure, getting in some exercise and eating a wide variety of fruits and veggies. Maintaining a healthy weight can be pretty important as well. Some studies have linked obesity with worse brain health, though much of that research has used BMI to determine the weight class of study participants, and BMI is not always the most accurate measure of weight. For example, someone can have a lot of lean mass—including muscle and bone—and low body fat, yet rank in the “obese” BMI category. 

For this reason, European researchers decided to use waist-to-hip ratio instead of BMI since abdominal fat may be a more accurate measure of disease risk. These researchers wanted to know if diet quality and abdominal fat during middle age are associated with cognitive decline at older ages. They published their findings in JAMA Network Open. Here’s what they found.

How Was This Study Conducted?

Researchers drew data from a long-term study called the Whitehall II Study at University College London. This study began in 1985 and looked at the relationship between socioeconomic factors, work conditions and health outcomes in people who worked in British public service. Over 10,000 participants were followed for 30 years, which were broken up into 13 study “waves.” Waist-to-hip ratio (WHR) was measured during five of those waves.

For this study, researchers also used brain MRI scan data from a random subset of the larger Whitehall II Study. That study was called the Whitehall II Imaging Substudy at the University of Oxford, and it included 775 participants who received functional brain MRI scans. 

The study at hand consists of two cohorts. The first, called the diet cohort, was made up of 506 participants, 79% of them male. Data was drawn from three waves of the Whitehall II study, and the average participant age was 48 at the first wave used and 70 when the MRI scans were performed. The second cohort for this study was called the WHR cohort. It was made up of 657 participants, 80% of them male, with similar ages to the diet cohort on average.

Diet quality was determined via food frequency questionnaires given during three of the waves. After data was collected, participants’ diet quality was assigned a score using the Alternative Healthy Eating Index-2010—generally, the higher the number, the healthier the diet. 

Abdominal adiposity was determined using the WHR, which was estimated by measuring hip and waist circumferences and then dividing the waist circumference by the hip circumference. The lower the ratio, the less abdominal adiposity. 

Researchers also examined participants’ brain scans. The MRI brain scans were functional—as opposed to still, snapshot images of the brain—allowing the researchers to examine blood flow in the brain, which is a measure of brain function.

What Did This Study Find?

Statistical analysis suggests that higher diet quality and lower WHR during the study period were associated with better structural and functional connectivity in the brain later in life. In addition, a lower WHR during midlife was associated with better working memory and executive function later in life. 

In contrast, higher abdominal fat in midlife was associated with worse cognitive performance in older age, including fluency, episodic memory, working memory and executive function. This was, in part, evidenced by higher widespread diffusivity of white matter in the brain. 

White matter is brain tissue composed of nerve fibers that facilitate rapid transmission of electrical signals between different brain regions and the spinal cord. For your brain health, you definitely want to keep your white matter intact. These researchers found that, on average, about 25% of white matter tracts were negatively affected in people with higher WHR during midlife.

How Does This Apply to Real Life?

Another study has suggested that compared to imbalanced diets—like high-protein, low-fiber diets—a healthy, balanced diet that includes a variety of foods may be better for brain health. This current study seems to support this notion.

The MIND diet—a fusion of the Mediterranean and DASH diets—focuses on brain-healthy nutrients, including antioxidants, vitamins, minerals, fiber, protein and healthy fats. And there’s a bonus: the MIND diet is also good for your heart and can be great for people with diabetes. 

The MIND diet is flexible and can be tailored to your preferences. To get started, try our Simple 7-Day Cognitive Health Meal Plan. Created by a registered dietitian, it includes meals and snacks for seven days—all the recipes you need to feel inspired in the kitchen. 

Other than diet, there are activities you can engage in that will support your brain. Meditating and practicing yoga—or moving your body more through other activities—can reduce stress and protect your brain. Ditto for getting plenty of quality sleep. Since the brain is at least 73% water, staying well-hydrated is an easy way to diffuse brain fog and improve concentration.

Keep your brain active by learning new skills, reading and challenging it with various types of puzzles. And spend time with loved ones, since loneliness has been associated with an increased risk of dementia.

The Bottom Line

This study suggests that a healthy, balanced diet and an optimal amount of abdominal fat during the mid-life years may lead to a healthier brain later in life. As with any research, more needs to be done to investigate the connection further.

Many factors influence abdominal fat, including diet, exercise, stress and sleep. If you feel like you may need a whole-health overhaul, start with small changes to your routines that you can build on over time. A little less screen time before bed so you can sleep better could be a great first step, or maybe you could aim to try a new healthy recipe each week to get more veggies and healthy fats and proteins into your day. Sometimes the little changes can reap big rewards down the road.