The Science Behind Alzheimer’s Prevention in the Brain Health Kitchen
The scientific study of Alzheimer’s disease is undergoing rapid and profound change. As a practicing physician in 2010, I did not have much to offer my patients to help them prevent Alzheimer’s disease. Back then, the two primary known risk factors — getting older and having a family history of dementia — were two things we just couldn’t change.
The focus of research was to find a drug to cure or halt the course of the disease, not on Alzheimer’s prevention. But despite more than 100 ongoing clinical trials studying more than 200 experimental drugs over 30 years, we still don’t have a cure. We don’t even have effective drug therapy for those suffering from Alzheimer’s disease.
Research Shifts to Preventing Alzheimer’s
When the National Institute of Health convened for a state-of-the-science Alzheimer’s meeting in 2010, they sent out a plea to the scientific community to focus their research on prevention. They encouraged researchers to determine the impact of factors we have the power to change, such as blood cholesterol, high blood pressure, physical exercise, and nutrition.
Thanks to this new focus on prevention, we now have a better understanding of how to reduce a person’s Alzheimer’s risk. And even though all those decades of research failed to bring an effective drug to market, there were critical breakthroughs. For example, we now have a tool to detect the buildup of amyloid-beta in the brain, a key pathological feature of Alzheimer’s disease. Just 10 years ago, the only way to diagnose Alzheimer’s disease was by autopsy after the patient died. Now we can study living brains with positron emission tomography (PET) scans. Discovering amyloid-beta in the brains of patients 20 to 30 years before the onset of Alzheimer’s symptoms has helped us understand how the disease evolves, and how better to delay it.
Understanding the Genetics of Alzheimer’s
Changing technology in the field of genetics was another game changer for Alzheimer’s researchers. Back in 2010, the only identifiable genetic risk factor we knew of was Apolipoprotein E (APOE) 4, one form of the APOE gene. Now researchers have identified a growing list of genetic mutations linked to Alzheimer’s disease. Some genes, like APOE4, are associated with late-onset (after age 60) Alzheimer’s. Others are linked to the devastating early-onset form in which multiple family members are diagnosed in their 30s, 40s, and 50s.
Researchers have identified genes that affect the brain’s inflammatory response to aging, the metabolism of lipids, and cellular functions that transport tau protein, a key substance that accumulates in the brains of Alzheimer’s patients. In fact, at the time of the NIH’s last Alzheimer’s Disease Progress Report in 2014, there were a whopping 24 genetic mutations being actively studied. (Read the full report here.)
What could be more exciting than discovering genes linked to Alzheimer’s disease? How about the discovery that environmental factors can determine whether or not those genes are expressed. Our knowledge of epigenetics — chemical modifications, or marks, on DNA that turn gene activity on and off — has exploded in recent years. Researchers are figuring out how we can keep these newly discovered Alzheimer’s genes from getting turned on by modifying our lifestyle and environmental factors. We’re talking about diet, exercise, how we deal with stress — factors we have the power to change.
The Case for Brain Healthy Food
All of this brings us back to the rationale behind eating a diet packed with brain healthy foods to reduce the risk of Alzheimer’s. Nutrition science has exploded in the last several years in three general areas. First, epidemiologists are studying groups of people over time to see if what they eat, or a certain dietary pattern like the Mediterranean diet, has an effect Alzheimer’s risk.
Secondly, researchers are looking at single or multiple nutrients to see if they play a role in Alzheimer’s — things like omega-3 fatty acids, caffeinated foods, vitamin D, and curcumin, one of the active ingredients in turmeric.
Thirdly, researchers are trying to figure out if the way we eat has an effect on dementia risk. Does restricting calories or fasting periodically affect brain health? Proponents of the ketogenic diet, a low carbohydrate/high fat diet that mimics starvation, believe ketones are a more brain healthy fuel than glucose. A few small studies on the effects of the ketogenic diet on memory in those with early dementia are intriguing — some patients did improve. We need more studies to determine if flooding the brain with ketones is actually a good thing to do.
The Mediterranean Diet: Good for the Heart and the Brain
What’s the best diet on the planet? No one knows the answer to that question. But the one with the most data to back it up is the Mediterranean diet. You’ve likely seen the Mediterranean Diet Pyramid with its base of abundant fruits, vegetables, grains, nuts, legumes, and generous amounts of olive oil. Several meals per week include fish or seafood. Poultry, eggs, cheese and yogurt are eaten less frequently, and meats and sweets are considered occasional treats. One hallmark of the Mediterranean diet: Meals are enjoyed in the company of friends and family, at a leisurely pace, and washed down with a moderate amount of red wine.
As a practicing physician, when patients asked me what they should eat, I gave them a copy of the Mediterranean Diet Pyramid. Hundreds of studies have shown it to be associated with a reduced risk of cardiovascular disease, diabetes, stroke, and obesity. Now researchers are taking a look at how the Mediterranean diet can help prevent Alzheimer’s too.
A meta-analysis of prospective cohort studies, published in the British Medical Journal in 2008, showed that those who mostly ate a Mediterranean diet had less Alzheimer’s disease and less Parkinson’s, another chronic neurodegenerative disease.
The PREDIMED study on heart attack and stroke
One Med diet study in particular, the PREDIMED study, published in the New England Journal of Medicine in 2013, showed an incredible reduction in heart attack and stroke in over 7000 men and women who were at high risk for cardiovascular disease. They were divided into three study arms: general dietary advice about a low fat diet, a Mediterranean diet supplemented with extra olive oil, or a Mediterranean diet supplemented with nuts. Those on the Mediterranean diet had 30% less heart attacks, strokes and death from all causes of cardiovascular disease. The results were so compelling that the researchers stopped the study ahead of time so that the low fat diet group could switch to a Mediterranean diet too.
An emerging theme of Alzheimer’s prevention builds on what we already know about preventing heart disease: What’s good for the heart is good for the brain. We have known for decades the recipe for good cardiovascular health: a plant-based diet (like the Mediterranean diet), regular exercise, smoking cessation, stress reduction, and maintaining a healthy weight. The same is holding true for Alzheimer’s prevention. That’s because maintaining healthy blood vessels also impact brain health. Blood vessel disease causes up to 20% of all dementias. Conditions like hardening of the arteries, leading to multiple small strokes, impairs blood flow to the brain. And healthy blood vessels prevent Alzheimer’s in ways we are just starting to understand.
The MIND Diet Study Defines 10 Brain Healthy Food Groups
Brain Works cooking curriculum teaches findings from the MIND diet study out of Rush University in Chicago, published in 2015 in the journal Alzheimer’s and Dementia. Researchers in the department of nutritional epidemiology, led by Dr. Martha Clare Morris, created a small sensation with their 4.5 year study of 758 dementia-free participants who kept diligent food diaries for the duration of the study.
MIND — Mediterranean-DASH Intervention for Neurodegenerative Delay — is a combination of the Med diet and the DASH diet, a plan designed to reduce hypertension. The researchers divided foods into 10 brain-healthy food groups and 5 brain-unhealthy ones. Participants’ diets were assessed weekly with a MIND diet score, a tally of brain healthy and unhealthy foods consumed.
Those with the highest MIND diet score, eating more brain healthy and less brain unhealthy foods, had a 53% reduction in Alzheimer’s risk. Those that did not follow the guidelines rigorously — meaning they ate a lot less brain healthy foods — still had a significantly reduced risk of Alzheimer’s of 35%. These numbers stunned the scientific community. Never before had a study shown such a dramatic impact of diet on Alzheimer’s risk.
Reducing Alzheimer’s risk by this degree is equivalent to adding 7.5 years to one’s brainspan (the number of years a brain is functioning at a high level.)
Alzheimer’s prevention in a Blue Zone
In the Brain Health Kitchen, we aspire to be high functioning 100-year olds, and we want to eat like them too. So we study the foods eaten by the world’s longest living people, those that live in what Dan Buettner describes as Blue Zones.
As a National Geographic fellow, Buettner created the Blue Zones study to examine the food and lifestyle in the parts of the world with the highest density of centenarians. In places like Sardinia, Italy, Okinawa, Japan, and Loma Linda, California, groups of elderly people were not just living to 100, they were thriving in good health.
Over more than 10 years of study, Buettner has described common elements in the Blue Zones diet and lifestyle. Brain Works Kitchen recipes incorporate many of these foods in its recipes. Blue Zone residents eat a mostly plant-based diet, with many common elements of the Mediterranean diet. Some of the Blue Zones foods we love: sweet potatoes, fennel, avocados, wild greens, shiitake mushrooms, barley, salmon and chickpeas.
FINGER study shows improved brain function
Some of the most intriguing studies in the last five years focus not just on preventing Alzheimer’s with food, but improving cognitive function. The FINGER study, published in 2013 in Lancet , was a breakthrough in evaluating the effects of lifestyle on brain health. FINGER stands for the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability. A multi-center, randomized, controlled trial from Finland, FINGER researchers evaluated 1200 participants in their 60s and 70s. Most were healthy but were at risk for cognitive decline based on their cardiovascular risk factors.
FINGER participants were randomized into two groups: one was given general nutritional advice, the other was given a program of diet, exercise, control of cardiovascular risk factors (such as blood cholesterol), and brain training. Over two years, the intervention group had a 25% improvement in the overall cognitive score compared with the control group.
How did the FINGER intervention help with brain function? Participants showed improvement in processing ability and executive function. In other words, they were able to perform more complex brain tasks faster. The diet? It was a variation of the Mediterranean diet.
Ongoing Alzheimer’s studies
The National Institute of Health lists more than 50 ongoing studies focused on the prevention of Alzheimer’s in healthy participants or those with mild cognitive impairment. The impacts of aerobic exercise, sleep quality, and modification of cardiovascular risk factors are all being studied in separate trials. Populations of Latinos and African-Americans are being studied to understand why they are afflicted with Alzheimer’s at earlier ages than non-ethnic groups. There are intervention trials for those who carry the Apoe4 gene. A much anticipated trial studying families with dominantly inherited Alzheimer’s is due for completion in 2020.
The MIND diet study began phase 3 clinical trials this year. This randomized trial will compare participants on the the MIND diet with a matched cohort given general nutrition advice. If the MIND diet replicates its initial finding of reducing Alzheimer’s risk by 53%, we will have compelling data regarding the power of brain healthy foods.
Our body of reliable Alzheimer’s prevention data will be augmented as the results of these studies roll in over the next five years. Stay tuned to the Brain Health Kitchen; we are paying close attention.