How to Avoid Dementia
Dementia doesn’t just hit close to home for me, it hit my actual home. When I was about a year into medical school, my dad, who had been the CEO of a large company, started missing meetings and forgetting things. Since he had a photographic memory, especially for numbers, this seemed odd. He was 60 years old. I’d like to tell you that we caught it early, that he received the best care, and that we had many more good years together, but that’s not how the story of Alzheimer’s disease went for my family. He died eight years later.
The trouble with dementia – and I’m focused on Alzheimer’s here – is that the more you look into it, the more you realize that we don’t know very much about what causes it, and that the drugs we have to treat it don’t work very well.
We do know that a genetic component exists for the development of Alzheimer’s. Over half of Alzheimer’s patients carry at least one copy of the APO e4 gene. Each person has two different copies of the gene, so you could be e4/e4 (highest risk), e3/e4 (intermediate risk), or e3/e3 (low risk), for example. But there are plenty of people with two copies of the e4 gene that never develop dementia, and there are also people with zero copies who do develop it. So while APO e4 is one of many risk factors for Alzheimer’s, it’s not the whole deal. If you want to know what variant you have, you can test for it through most DNA testing companies, including 23 and Me (no affiliation).
For decades, scientists thought that Alzheimer’s disease was caused by the accumulation of proteins called amyloid (which cause plaques in the brain) and tau (which cause tangles). Dozens of pharmaceuticals have been developed to reduce and remove these plaques and tangles, but have they reversed Alzheimer’s disease? Hardly. This has caused plenty of confusion in the scientific community, and things got particularly bad when a 2022 article in the journal Science suggested that the key images in a study that linked amyloid to Alzheimer’s had actually been falsified (1). So things went back to square one: it’s not clear whether Alzheimer’s disease is caused by amyloid and tau, nor is it clear that we can treat the disease by removing these proteins.
More recently, other theories have been developed as to what causes Alzheimer’s. What if amyloid and tau were the consequences, not the causes, of dementia? Could that explain why the drugs to remove them don’t reverse the disease?
The first theory is that a reduction of blood flow to the brain causes dementia, and that it’s primarily a vascular disorder. Indeed, neuroimaging has confirmed that a drop in blood flow to the brain seems to predict when a person’s symptoms will worsen. It’s also important to note that things that reduce blood flow to the brain, such as smoking, high blood pressure (because your brain compensates for high blood pressure by constricting its blood vessels), stroke, and head injury, are all risk factors for dementia.
Another theory is that dementia is a metabolic disorder of the brain closely related to type 2 diabetes. You might hear Alzheimer’s being called “type 3 diabetes,” and this is why. Having type 2 diabetes increases a person’s risk of dementia just as much as does having an APO e4 gene (2). Even insulin resistance, the precursor to type 2 diabetes, will increase your risk of Alzheimer’s. Imaging studies show that people with dementia have lower glucose metabolism – and a harder time getting glucose into their brain cells – than do their healthy peers.
So what about early detection? It’s clear that Alzheimer’s – like other types of dementia – has a long runway before symptoms become obvious. I’m convinced that my dad’s high-functioning and frankly brilliant mind allowed him to cover for himself long before he missed his first meeting or got lost driving to work. If his cognition had been assessed throughout his 50s and even before, he might have caught the problem earlier and at least slowed the progression of his disease. UCLA’s Dale Bredesen, MD, a prominent researcher on Alzheimer’s, recommends that everyone get a “cognoscopy” (like a colonoscopy for your brain, get it?), which includes blood tests, a thorough cognitive assessment, and a brain MRI, full-stop, regardless of symptoms. Another important test to consider is an evaluation of a person’s smell, since the olfactory (smell) neurons are among the first to be affected by Alzheimer’s disease.
Prevention
Exercise: The single most powerful tool for the prevention of Alzheimer’s is exercise. Hands down. Exercise increases the blood flow to our brains and keeps us sensitive to insulin, which helps the brain use glucose for fuel. If you’re asking whether cardio or strength is better, the answer is both. Endurance training produces brain-derived neurotrophic factor (BDNF) which aids cognition and memory, and it decreases inflammation and oxidative stress. Strength training is important because a person’s strength (measured by grip strength) is actually a very strong predictor of dementia. As a person’s grip weakens, their risk of dementia goes up, regardless of anything else, including age, diabetes, cancer, and smoking (3).
Ketosis: Specifically in dementia, there may also be a role for a ketogenic (which means very low-carb) diet. The brain can only use glucose and ketones for fuel, and we think glucose metabolism is impaired in dementia. So if we bypass the glucose system by eliminating most carbohydrates, our brains can use ketones instead, which may turn out to be more effective. A review of randomized controlled trials found that keto-based therapies improved memory in people with early-stage Alzheimer’s disease (4).
Sleep: Deep sleep, or slow-wave sleep, is the stage of sleep when the brain is able to heal itself. Deep sleep repairs the brain by clearing away debris. It’s no coincidence that patients with dementia don’t sleep much and that they exhibit a “sundowning” effect, where their symptoms get worse as the day goes on. Never mind that poor sleep contributes to insulin resistance, stress, and lack of exercise. Current research is ongoing as to whether inducing a deep sleep-like state in the brain can help prevent or slow Alzheimer’s.
Dry sauna: studies from Finland have shown that four 20-minute dry sauna sessions per week can reduce the incidence of Alzheimer’s, presumably by improving cardiovascular function.
Reduce or eliminate alcohol: heavy alcohol use has been shown to promote dementia due to alcohol’s toxic effect on brain cells.
Hearing support: hearing loss correlates with dementia because a person with hearing loss loses specific inputs to the brain and tends to withdraw. There is an ongoing study to look at whether improving hearing through hearing aids can improve memory.
Oral hygeine: a certain bacteria species that causes gum disease, called P. gingivalis, has been found in the brains of Alzheimer’s patients. It’s not clear that this bacteria causes dementia, but brushing and flossing should be a priority
Fish oil: The omega-3 fatty acid DHA found in fish oil may promote brain health, especially in e4 carriers. Patients at risk for dementia may need higher doses of fish oil to combat the metabolic dysfunction associated with Alzheimer’s.
Finally, what about the importance of brain games in cognitive decline? Much as you’d think they would help, if you have that extra half-hour in your day, the biggest bang for your buck has still been shown to be exercise. If you exercise and take care of your metabolic health, you’ll probably get better at brain games. While there’s nothing wrong with mind teasers, they don’t seem to address the underlying causes of the disorder we call dementia.
I hope that helps you understand a little bit more about dementia and what we can do to prevent it. Thank you for reading - I’d love to know what you think!
In good health,
Gina
References:
Most of this information is adapted from Peter Attia, MD’s book Outlive. There is much more information contained in the book than I can present here, including even more tips for preventing dementia. So, for a robust read on dementia and on longevity in general, I highly recommend this book.
(1) Piller C (2022) Blots on a page. Science.
(2) Cholerton et al. (2016) Type 2 diabetes, cognition, and dementia in older adults. Diabetes Spectr.
(3) Esteban-Cornejo et al. (2022) Handgrip strength and all-cause dementia incidence and mortality. J Cachexia Sarcopenia Musc.
(4) Grammatikopoulou et al. (2020) To keto or not to keto? Systematic review of randomized controlled trials assessing the effects of ketogenic therapy on Alzheimer’s disease. Adv Nutr.