Dietary Fiber Tied to Lower Dementia Risk - especially soluble fiber

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Batya Swift Yasgur, MA, LSW
March 07, 2022

Eating a high-fiber diet, especially one rich in soluble fiber, is linked to a lower risk of incident disabling dementia, new research shows.

Investigators administered a dietary survey to 3700 healthy adults at midlife and then followed them for up to 20 years. They found that participants who consumed the most fiber had approximately a 25% lower risk of developing dementia in later life.

"This study showed that people with a high intake of dietary fiber, especially soluble fiber, have a lower risk of dementia," study investigator Kazumasa Yamagishi, MD, PhD, professor, Department of Public Health Medicine, Faculty of Medicine and Health, Services Research and Development Center, University of Tsukuba, Japan, told Medscape Medical News.

"There are still many unknowns about the causes of dementia, and it is not appropriate to determine causality based on the results of a single cohort study. However, the results of this study can be said to be one of the findings that will lead to the prevention of dementia," Yamagishi said.

The study was published online February 6 in Nutritional Neuroscience.

Brain-Gut Interaction

Brain-gut interaction has recently received attention for its potential involvement in the development of dementia. "The concept of brain-gut interaction emerged from the idea that the central nervous system communicates bidirectionally with the gastrointestinal tract, suggesting that the gut microbiome may influence brain plasticity and cognitive function," the authors write.

A diet high in soluble fiber attenuates neuroinflammation in mouse models. Other animal studies have suggested that insoluble fiber might also have a beneficial effect on the microbiome.

The researchers wanted to see whether dietary fiber intake — especially soluble fiber — is associated with a reduced risk of dementia. They also investigated whether there was any difference between dementia in patients with vs without a history of stroke.

In a previous study, these same researchers reported an inverse association between eating beans, which are high in fiber, and risk of disabling dementia. In the current study, the researchers extended the analyses to dietary fiber intake of total, soluble, and insoluble fibers, as well as other fiber-containing foods, such potatoes, vegetables, and fruits. However, they distinguished potatoes from other vegetables because the composition of starch in potatoes differs.

"Dietary fiber is a nutrient found in grains, potatoes, vegetables, and fruits and is known to affect intestinal bacteria," Yamagishi said. "Recently, some experimental studies have shown that intestinal bacteria may be involved in cognitive functions as well as diseases of the digestive tract. However, there have been no studies that have actually examined the relationship between dietary fiber intake and the subsequent risk of dementia in large numbers of general people."

The researchers turned to participants in the Circulatory Risk in Communities Study (CIRCS), an ongoing dynamic community cohort study involving five communities in Japan. The current study focused on communities where disabling dementia surveillance is conducted.

Participants (n = 3739) ranged in age from 40 – 64 years (mean age, 51 years) at the time they completed the 24-hour dietary recall survey, and they participated in annual health checkups from 1985 – 1999. Potential risk factors for disabling dementia were measured at the time the dietary surveys were conducted. Participants were then followed for a median of 19.7 years (1999 – 2020) to confirm incident, disabling dementia.

"Disabling dementia" was defined as dementia that required care under the National Long-Term Care Insurance System and was further categorized on the basis of having a history or not having a history of stroke.

The researchers divided participants into quartiles, based on the amount of total, soluble, and insoluble intake reported in their surveys. They found that men tended to consume less total fiber compared to women.

Unclear Mechanism

During follow-up, 670 participants developed disabling dementia.

Total fiber intake was "inversely and linearly" associated with risk of incident dementia, the authors report, with each successive quartile associated with a lower risk compared to the lowest quartile (P for trend = .03).

Quartile	Multivariate HR (95% CI)
Second	.83 (.67 – 1.04)
Third	.81 (.65 – 1.02)
Fourth (highest)	.74 (.57 – .96)

The association remained after adjusting for potential factors that might affect dementia onset, such as body mass index, systolic blood pressure, antihypertensive medication use, serum total cholesterol, cholesterol-lowering medication, and diabetes (P for trend = .05).

"The inverse association was more evident for soluble fiber intake and was confined to dementia without a history of stroke," the authors report. Moreover, potatoes, not vegetables or fruits, showed a similar association.

"The mechanisms are currently unknown but might involve the interactions that take place between the gut and the brain," Yamagishi said in a release.

"One possibility is that soluble fiber regulates the composition of gut bacteria. This composition may affect neuroinflammation, which plays a role in the onset of dementia," he suggested. "It's also possible that dietary fiber may reduce other risk factors for dementia, such as body weight, blood pressure, lipids, and glucose levels."

The authors note several limitations. For example, they did not distinguish between Alzheimer's and non-Alzheimer's dementia. Moreover, they classified dietary habits on the basis of a single survey, and participants' dietary patterns might have changed over the study period.

Additionally, Yamagishi noted, it is "important to confirm the association in other populations."

Balance Is Key

Commenting for Medscape Medical News, Uma Naidoo, MD, director of nutritional and lifestyle psychiatry, Massachusetts General Hospital, Boston, and nutrition educator at Harvard Medical School, said the study "adds to the growing pool of evidence suggesting that a diet rich in colorful, plant-based foods can benefit our neurological and psychiatric health, especially as we age."

Naidoo, also a chef and the author of This Is Your Brain on Food, who was not involved in the study, continued, "In nutritional psychiatry, balance is key and therefore consuming a well-rounded diet including ample amounts of fiber — particularly from sources like steel-cut oats, beans, lentils, and numerous other fruits and vegetables — can be part of a healthy lifestyle and prevention against cognitive decline in later years.

"While the study authors admit to limitations within the study, in my opinion, eating healthier has so many mental and physical health benefits that it's a nutritional psychiatry no-brainer," she added.

The study was partly supported by Health and Labour Science Research Grants for Dementia from the Ministry of Health, Labour and Welfare of Japan; JSPS Kakenhi; FULLHAP; and the Osaka University International Joint Research Promotion Programme with University College London. The authors and Naidoo report no relevant financial relationships.

The #1 Cause of Dementia, According to Science - Aging

 Website content extracted from: The #1 Cause of Dementia, According to Science — Eat This Not That

Everything you need to know about the neurodegenerative condition.

BYLEAH GROTH

OCTOBER 12, 2021

FACT CHECKED BYALEK KORAB

According to the Centers for Disease Control and Prevention, there are an estimated 5 million adults living with dementia—and that number grows every year. In fact, by the year 2060 they predict that number to multiply to nearly 14 million. While often referred to as a disease or illness, dementia is actually a general term to describe "impaired ability to remember, think, or make decisions that interfere with doing everyday activities." While occasionally forgetting a name or misplacing car keys is a normal part of aging, dementia isn't. Here is everything you need to know about it—including the number one cause of the memory-impairing condition. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You May Have Already Had COVID.

1

What Is Dementia?

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According to the National Institutes of Health's National Institute on Aging, dementia is defined by the loss of cognitive functioning and can range from mild to severe. This includes thinking, remembering, and reasoning—in addition to behavioral abilities "to such an extent that it interferes with a person's daily life and activities," they explain. "These functions include memory, language skills, visual perception, problem solving, self-management, and the ability to focus and pay attention." Furthermore, some people with the condition cannot control their emotions and their overall personality may change. In worst case scenarios, the person cannot live on their own and has to depend on others to help with basic activities of living. 

Ai Prevents Dementia

While it is normal to lose neurons during the aging process, in the case of dementia, more of these once-healthy nerve cells stop working, lose connections with other brain cells, and die. 

Another thing about dementia? It is progressive, explains Carlyn Fredericks, MD, memory loss expert in Yale Medicine's Department of Neurology. "Unfortunately, dementia symptoms get worse over time despite our best efforts," she tells Eat This, Not That!

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2

What Are the Types of Dementia and What Happens If You Have Them

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There are several different types of neurodegeneration, as outlined by the CDC. 

Alzheimer's Disease: Alzheimer's is the most common form of dementia, responsible for 60 to 80 percent of cases. It is caused by specific changes in the brain. It usually manifests itself as memory issues—like trouble recalling recent events, including conversations that just occurred. Then, later on after the disease progresses, someone might have trouble remembering more distant memories. Other issues—difficulty walking or talking or personality changes—are also common later on. The biggest risk factor? Family history. "Having a first-degree relative with Alzheimer's disease increases the risk of developing it by 10 to 30 percent," the CDC explains. 

Vascular Dementia: Strokes or other blood flow issues can also lead to dementia in the form of what is called vascular dementia, accounting for about 10 percent of cases. Other risk factors include diabetes, high blood pressure and high cholesterol. "Symptoms vary depending on the area and size of the brain impacted. The disease progresses in a step-wise fashion, meaning symptoms will suddenly get worse as the individual gets more strokes or mini-strokes," explains the CDC. 

Lewy Body Dementia: This form of dementia manifests itself in memory loss as well as movement or balance problems like stiffness or trembling. "Many people also experience changes in alertness including daytime sleepiness, confusion or staring spells. They may also have trouble sleeping at night or may experience visual hallucinations (seeing people, objects or shapes that are not actually there)," the CDC explains. 

Fronto-Temporal Dementia: Changes in personality and behavior define fronto-temporal dementia, named after the part of the brain affected. "People with this condition may embarrass themselves or behave inappropriately. For instance, a previously cautious person may make offensive comments and neglect responsibilities at home or work. There may also be problems with language skills like speaking or understanding," the CDC explained. 

Mixed Dementia: Individuals may experience more than one type of dementia in the brain, especially if they are over 80. "It is not always obvious that a person has mixed dementia since the symptoms of one type of dementia may be most prominent or may overlap with symptoms of another type," the CDC notes. And, when there is more than one type of dementia, disease can progress much more quickly.

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3

How Do I Know I Have It?

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There are many symptoms of dementia, according to the CDC, with many of them outlined above. The most common are memory loss, issues with paying attention, communication problems, reasoning, judgment, and problem solving issues and visual perception beyond typical age-related changes in vision.

Specific signs that can point to dementia include getting lost in a familiar neighborhood, using unusual words to refer to familiar objects, forgetting the name of a close family member or friend, forgetting old memories, or not being able to complete tasks independently.

RELATED: Warning Signs You're in Danger of a Stroke, Says CDC

4

Here Are the Top Contributing Factors

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According to the CDC, there are many risk factors of dementia. 

Age: The older you get, the more likely you are to develop dementia.

Family history: Dementia runs in the family, according to the CDC. "Those who have parents or siblings with dementia are more likely to develop dementia themselves," they explain. 

Race/Ethnicity: According to the CDC, older African Americans are twice more likely to have dementia than whites, while Hispanics are 1.5 times more likely to have dementia than whites.

Heart Health: Those with poor cardiovascular health are more likely to develop dementia. High blood pressure, high cholesterol, and smoking can all play a role. 

Traumatic Brain Injury: "Head injuries can increase the risk of dementia, especially if they are severe or occur repeatedly," the CDC says. 

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5

What Is the Number One Cause?

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According to the CDC the number one contributing factor for dementia is increasing age, with most cases impacting those 65 and over. The second? Family history.

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6

How to Prevent It

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While in most cases, dementia is not preventable, Dr. Fredericks explains that there are a lot of contributing factors that you may be able to do something about, "including improving your level of exercise (especially cardiovascular fitness), decreasing heavy alcohol use, improving your sleep (and treating sleep apnea, if present), eating well (a Mediterranean diet seems to be especially helpful), and making sure you are working with your doctors to keep a close eye on chronic illnesses such as high blood pressure, high cholesterol, and diabetes," she explains.

The Alzheimer's Association has detailed the best practices to prevent dementia in 10 Ways to Love Your Brain. "Growing evidence indicates that people can reduce their risk of cognitive decline by adopting key lifestyle habits," they explain. 

RELATED: Delta Symptoms Usually Appear Like This

7

How Is Dementia Treated?

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Unfortunately, there is no cure for most types of dementia, including Alzheimer's, per the CDC. However, there are medications that can help protect the brain or manage symptoms, including anxiety or behavior changes.

RELATED: These 5 States are the Only Ones Where COVID is Going Up

8

What to Do If You Notice Symptoms

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If you believe you or a loved one is demonstrating symptoms of dementia, the NIH recommends contracting your medical provider for an assessment. "Don't be afraid to get them checked out early!" encourages Dr. Fredericks. "Having an experienced physician evaluate you and determine whether there is a need for further testing—whether blood tests, brain imaging, or pen-&-paper neuropsychological testing—can help you identify the cause of your symptoms as early as possible (and reassure you if what you are experiencing is more likely the result of normal aging)." And to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.

LEAH GROTH

Leah Groth has decades of experience covering all things health, wellness and fitness related

Don't ask someone with dementia if they "know your name" or "remember you"

Repetitive negative thinking linked to dementia risk

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Persistently engaging in negative thinking patterns may raise the risk of Alzheimer's disease, finds a new UCL-led study.

In the study of people aged over 55, published in Alzheimer's & Dementia, researchers found 'repetitive negative thinking' (RNT) is linked to subsequent cognitive decline as well as the deposition of harmful brain proteins linked to Alzheimer's.

The researchers say RNT should now be further investigated as a potential risk factor for dementia, and psychological tools, such as mindfulness or meditation, should be studied to see if these could reduce dementia risk.

Lead author Dr. Natalie Marchant (UCL Psychiatry) said: "Depression and anxiety in mid-life and old age are already known to be risk factors for dementia. Here, we found that certain thinking patterns implicated in depression and anxiety could be an underlying reason why people with those disorders are more likely to develop dementia.

"Taken alongside other studies, which link depression and anxiety with dementia risk, we expect that chronic negative thinking patterns over a long period of time could increase the risk of dementia. We do not think the evidence suggests that short-term setbacks would increase one's risk of dementia.

"We hope that our findings could be used to develop strategies to lower people's risk of dementia by helping them to reduce their negative thinking patterns."

For the Alzheimer's Society-supported study, the research team from UCL, INSERM and McGill University studied 292 people over the age of 55 who were part of the PREVENT-AD cohort study, and a further 68 people from the IMAP+ cohort.

Over a period of two years, the study participants responded to questions about how they typically think about negative experiences, focusing on RNT patterns like rumination about the past and worry about the future. The participants also completed measures of depression and anxiety symptoms.

Their cognitive function was assessed, measuring memory, attention, spatial cognition, and language. Some (113) of the participants also underwent PET brain scans, measuring deposits of tau and amyloid, two proteins which cause the most common type of dementia, Alzheimer's disease, when they build up in the brain.

The researchers found that people who exhibited higher RNT patterns experienced more cognitive decline over a four-year period, and declines in memory (which is among the earlier signs of Alzheimer's disease), and they were more likely to have amyloid and tau deposits in their brain.

Depression and anxiety were associated with subsequent cognitive decline but not with either amyloid or tau deposition, suggesting that RNT could be the main reason why depression and anxiety contribute to Alzheimer's disease risk.

"We propose that repetitive negative thinking may be a new risk factor for dementia as it could contribute to dementia in a unique way," said Dr. Marchant.

The researchers suggest that RNT may contribute to Alzheimer's risk via its impact on indicators of stress such as high blood pressure, as other studies have found that physiological stress can contribute to amyloid and tau deposition.

Co-author Dr. Gael Chételat (INSERM and Université de Caen-Normandie) commented: "Our thoughts can have a biological impact on our physical health, which might be positive or negative. Mental training practices such as meditation might help promoting positive- while down-regulating negative-associated mental schemes.

"Looking after your mental health is important, and it should be a major public health priority, as it's not only important for people's health and well-being in the short term, but it could also impact your eventual risk of dementia."

The researchers hope to find out if reducing RNT, possibly through mindfulness training or targeted talk therapy, could in turn reduce the risk of dementia. Dr. Marchant and Dr. Chételat and other European researchers are currently working on a large project to see if interventions such as meditation may help reduce dementia risk by supporting mental health in old age.

Fiona Carragher, Director of Research and Influencing at Alzheimer's Society, said: "Understanding the factors that can increase the risk of dementia is vital in helping us improve our knowledge of this devastating condition and, where possible, developing prevention strategies. The link shown between repeated negative thinking patterns and both cognitive decline and harmful deposits is interesting although we need further investigation to understand this better. Most of the people in the study were already identified as being at higher risk of Alzheimer's disease, so we would need to see if these results are echoed within the general population and if repeated negative thinking increases the risk of Alzheimer's disease itself.

"During these unstable times, we are hearing from people every day on our Alzheimer's Society Dementia Connect line who are feeling scared, confused, or struggling with their mental health. So it's important to point out that this isn't saying a short-term period of negative thinking will cause Alzheimer's disease. Mental health could be a vital cog in the prevention and treatment of dementia; more research will tell us to what extent."