Can diet and waist-to-hip ratio predict brain health in older age?

ISLAMABAD, MARCH 17 (ONLINE): BMI has been used to measure a person’s health since the early 1970s.
Over the last few years, researchers have been examining waist-to-hip ratio (WHR) as a potential replacement for BMI.
Previous studies have linked having a higher WHR to an increased risk for cognitive impairment.
A new study says that people who follow a healthier diet and have a lower WHR during midlife may have better brain and cognitive health in older age.
Since the term “body mass index” or BMI was coined in the early 1970s, it has continued to be a main indicator of a person’s health.

As BMI is a measurement of a person’s body fat based on their height and weight, it is also used as a screening tool to assess a person’s risk for certain diseases like cardiovascular disease, type 2 diabetesTrusted Source, non-alcoholic fatty liver diseaseTrusted Source, and cancer.

Past research shows that BMI has some limitationsTrusted Source. For this reason, scientists have also been examining the use of waist-to-hip ratio (WHR) as a substitution for BMI.

Previous studies have found that WHR may be a better weight management toolTrusted Source than BMI, and have linked having a higher WHR to an increased risk for cognitive impairment.

Now, a new study recently published in the journal JAMA Network OpenTrusted Source has found evidence suggesting that people who follow a healthier diet and have a lower WHR during midlife may have better brain and cognitive health in older age.

Data collected during midlife over 30 years
For this study, researchers analyzed health data from participants of the Whitehall II Study, from where diet and WHR was measured three different times over 30 years, and its Whitehall II Imaging Substudy, where some participants also received brain MRI scans and cognitive testing.

The average age of the study participants was 48 from the start of the Whitehall II Study until they reached age 70, allowing researchers to focus on midlife.

“We focused on diet and WHR during midlife because this period represents a critical window for preventive interventions to maintain cognitive health and reduce dementia risk,” Daria E. A. Jensen, DPhil, postdoctoral fellow at the Clinic of Cognitive Neurology at the University Medical Center Leipzig and Neurology Department of the Max Planck Institute for Human Cognitive and Brain Sciences in Germany, visiting researcher at the Department of Psychiatry at the University of Oxford, and corresponding author of this study told Medical News Today.

“Our study aimed to address gaps in existing research by examining the long-term effects of overall diet quality and WHR (as a measure for abdominal fat) on brain connectivity and cognitive function. By leveraging data from the Whitehall II study, we sought to provide insights into how these factors influence brain health over time,” she said.

Lower WHR linked to improved cognitive function
At the study’s conclusion, Jensen and her team found that having higher diet quality and lower WHR in midlife were associated with structural and functional connectivity of the hippocampus at older age.

“This important finding highlights the critical role of modifiable lifestyle factors, such as diet quality and WHR management, in enhancing brain connectivity, particularly in the hippocampus — a region vital for memory and learning,” Jensen explained. “These findings suggest that interventions focused on improving diet and managing central obesity could be most beneficial when implemented during this critical period, potentially reducing the risk of cognitive declineTrusted Source and dementia in later life.”

Additionally, researchers observed that having a lower WHR in midlife was correlated to having a better working memory and executive function in older age.

“The association between a lower WHR in midlife and improved cognitive functions, such as working memory and executive function, underscores the importance of managing central obesity for cognitive health,” Jensen said.

“Our study found that higher abdominal fat in midlife was linked to lower cognitive performance scores across several domains, including fluency, episodic memory, working memory, and executive function. This suggests that interventions aimed at reducing abdominal fat could preserve cognitive abilities essential for daily functioning and decision-making in older age.”
— Daria E. A. Jensen, DPhil

“Furthermore, the relationship between midlife WHR and cognitive performance was mediated by white matter connectivity, indicating that metabolic health in midlife can impact brain structure, which in turn affects cognitive outcomes,” Jensen continued.

“These findings align with theories suggesting that lifestyle risk factors influence cognitive health through changes in (the) cerebral microstructure, highlighting the need for targeted interventions during midlife to promote long-term cognitive well-being,” she added.

The impact of lifestyle choices on brain health
MNT had the opportunity to speak with Molly Rapozo, RDN, a registered dietician nutritionist and senior nutrition and health educator at the Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, CA, about this study.

“As a dietitian and health coach I find this information helpful for guiding people with evidence-based decisions about what to focus on today to avoid chronic disease like Alzheimer’s in the future,” Rapozo said. “Many of my clients have seen their parents suffer from cognitive decline and would like to prevent this course in their own lives.”

“This study highlights the significant impact that lifestyle choices, particularly diet and managing abdominal fat, can have on brain health and cognitive function as we age. The association between better diet quality and enhanced brain connectivity, as well as the negative impact of higher WHR on cognitive functions, underscores the importance of maintaining a healthy lifestyle.”
— Molly Rapozo, RDN

Rapozo said that as the global population ages, the prevalence of cognitive decline and dementia is expected to rise, making it crucial to find effective interventions that can improve the quality of life for many individuals.

“Understanding how lifestyle factors influence brain health is essential, as it can lead to preventive strategies that reduce the risk of cognitive decline,” she continued. “Additionally, cognitive decline and dementia are associated with significant healthcare costs, and preventive measures can potentially reduce these costs by delaying or preventing the onset of these conditions.”

Tips for lowering waist-to-hip ratio during midlife
MNT also spoke with Monique Richard, MS, RDN, LDN, a registered dietitian nutritionist and owner of Nutrition-In-Sight, for her tips on how readers can make sure they are eating a high-quality diet and keep a lower WHR during their midlife to hopefully help protect their cognitive health as they age.

“Meeting with a registered dietitian nutritionist (RDN) would be a beneficial way to help clarify nutritional needs, as well as suggestions for specific neuroprotective recommendations,” Richard said.

Richard said that general diet and lifestyle modifications that are supportive of cognitive function include:

Understanding how the calorie goal for your individual body may translate into food group choices and meal planning.
Cooking with a variety of fresh or dried herbs and spices (thyme, garlic, rosemary, chives, dill, mint), vegetables (carrots, peppers, onions, tomatoes, celery, arugula, cabbage, Brussels sprouts, radishes, bok choy), whole grains (oats, sorghum, quinoa, long-grain rice), lean proteins, and healthy fats such as extra-virgin olive oil and fatty fish (sardines, salmon, tuna).
Hydrating with a variety of fruits, water, unsweetened beverages, and teas (black, green, herbal).
If eating out, understanding further ingredients and cooking methods of the meals and establishments you frequent.
A minimum of 150 minutes a week of moderate-intense movement with a mix of weight resistance activities.
Get social, and ditch the screen for personal interaction at meal time, which facilitates and engages emotional and psychological functions.
Keep learning new things — fire up those neurons by learning a new activity, like a language, dance, hobby, or craft.
Snack on nuts such as pistachios, almonds, walnuts, pecans, Brazil nuts, cashews.
Limit alcohol intake (women 1 serving per day and men 2 servings per day; a serving equals 1 1/2 ounces of liquor, a 12-ounce beer, or 5-ounce glass of wine).
Quit smoking (anything).
Bathe your brain in goodness: get some fresh air and sunshine often, make sure your vitamin D needs are met, and surround yourself with positivity, support, hope, and love.
“It’s never too late to make changes or to reap the rewards from those changes,” Richard said. “It’s National Nutrition Month, the theme is ‘Food Connects Us’ — food connects us to our culture, to our bodies, to each other. When we make positive choices for our body, we’re making positive choices for our brain.”