For years, we’ve been told that Alzheimer’s disease is simply a result of getting older; the same explanation often given as to why more women seem to develop Alzheimer’s; as they tend to live longer than men. However, upon closer examination of the data, this theory begins to unravel.
Age and Gender: Not the Whole Story
Yes, Alzheimer’s is more common in older people, so are most chronic diseases, but more than half of those who live into their 90s, never develop symptoms of Alzheimer’s. So age alone can’t be the cause. And why would women, who make up 60% of Alzheimer’s cases, far more than men, yet only live a few years longer, be so much more at risk? Oddly though, these statistics are reversed for Parkinson’s, with men getting the lion’s share. Whereas for other types of dementia, the risk is about equal.
If age were the cause, women should also be more at risk for those diseases, too.
So What’s Going On?
Let’s start with what we do know. Alzheimer’s is the most common, and most feared, form of dementia, but Parkinson’s is growing even faster, with global cases doubling every twenty years. But here’s the good news: scientists now believe that healthy lifestyle factors can build a strong resilience to most neurodegenerative diseases, preserving cognitive function in more than 80% of older adults. In fact eating a healthy diet together with exercise and other healthy lifestyle behaviours will significantly reduce the risk for multiple chronic diseases, including heart disease, diabetes and cancer; all risk factors for cognitive decline.
The Problem Starts Earlier Than You Think
Most people assume Alzheimer’s begins in old age, but damage to the brain starts accumulating decades earlier, usually when we are in our late 30's or early 40's. By this time the growing stage has stopped and the ageing process has begun. Although symptoms of cognitive decline won’t appear for another 20 - 25 years or so, but by then, the brain has already suffered significant harm.
A similar type of delay is seen with cardiovascular disease, where the effects of inactivity and an unhealthy diet, take approximately 12 years to show up as heart disease.
That is why, whether it’s for preventing Alzheimer's , heart disease or any chronic disease, the sooner we start the better, and waiting for symptoms to appear is waiting too long. Prevention has to start early, long before any memory loss begins or damage sets in. The earlier in life people begin healthy practices the slower the decline will be, and the more likely they are to achieve healthy ageing, often classified as reaching the age of 70 years without developing any major chronic disease.
The Search For Cause: Why the Amyloid Hypothesis Falls Short
Alzheimer’s is accompanied by a buildup of a protein called amyloid-beta, which, when damaged, clumps together and disrupts brain function, leading to the accumulation of another damaged protein called tau. This has led many researchers and drug companies to focus on removing amyloid beta, in the hope of slowing the disease. But results have been mixed. Two new drugs have shown some success in removing amyloid-beta, but unfortunately this only slowed the disease progression by a few months. These drugs are costly and can come with some serious side effects. The European Medicines Agency has yet to approved them, as they don’t accept that the benefits outweigh the risks associated with them.
Meanwhile, other studies have found that a simple daily multivitamin was more effective at preserving brain health, slowing cognitive ageing by two years, with no reported side effects.
This has led some scientists to question the dominant approach and ask: What if amyloid isn’t the cause, but is, rather a symptom of something deeper? A study published in 2024 In the Journal of American Medicine Association suggested that only about 12% of cases of Alzheimer’s disease could be attributed to amyloid-beta, with the remainder related to lifestyle behaviours. So, what is the deeper problem?
A New Suspect: Chronic Inflammation
A growing number of researchers, unhappy with the amyloid hypothesis, began to look elsewhere for a culprit and started to suspect that chronic inflammation may be at the root of frailty, a clinical condition associated with ageing, characterised by a decline in the body’s ability to maintain stability and recover from physical and medical stress. Which can then lead to heart disease, Alzheimer’s and other brain diseases. And unlike short-term (acute) inflammation — the body’s natural and helpful response to injury or infection — chronic inflammation is long-lasting and damaging.
What Drives Chronic, Low-Grade Inflammation?
Chronic inflammation is a key biological process in ageing and the development of age-related diseases, and is a result of multiple diverse factors that come from the accumulation of damage to our bodies over time. Obesity, smoking, damage to our skin caused by excess sun exposure or gastrointestinal issues caused by an unhealthy diet and excess sugar can all lead to damaging immune system responses. There are also external factors like environmental toxins, micro-plastics, infections, stress, inactivity and consuming ultra-processed foods that may collectively culminate in chronic inflammation and contribute to our immune system’s overall decline in effectiveness during ageing. A study found that people with Alzheimer’s were more likely to have an inflamed immune system.
Inflammation smoulders in the body for months or years, slowly spreading and harming tissues and organs, including the brain, affecting immune function and driving tumour growth. The longer a person is exposed to low-grade chronic inflammation the more damage is done to their general health.
Inflammation can also start as a result of viral infections such as herpes simplex (cold sores) and varicella zoster (chicken pox and shingles), which have both been associated with increased risk for Alzheimer’s disease.
An increased risk for Alzheimer’s has also been seen in women who experience early menopause, or in people who have asthma, an inflammatory disease of the airways, that usually starts at a young age.
It is generally believed that those exposed to inflammation for a greater parts of their lives than normal, are at greater risk for Alzheimer’s disease in later years.
Chronic inflammation can link together nearly every known risk factor for Alzheimer’s — from poor sleep, hearing loss, depression, to obesity, environmental toxins, infections, and stress. In other words, inflammation may be the common thread that makes all these things harmful to the brain.
“Inflammation is the root cause of every chronic disease.”
Dr. Sara Gottfried, Department of Integrative Medicine,
Thomas Jefferson University
More recently, neuroinflammation has also been suspected of being a cause in cases of schizophrenia and obsessive compulsive disorder. A study published in 2024 found that treating schizophrenic patients with Rituximab, a drug used to reduce inflammation associated with certain cancers and autoimmune diseases such as lupus and rheumatoid arthritis, resulted in significant improvements in symptoms, increasing brain function and connectivity as well as improving psychosocial functioning. The improvements were so significant that Columbia University is beginning a screening programme for autoimmune disorders among all patients hospitalised in the New York State mental health system.
The Inflammation-Ageing Link
Inflammation interacts with other aspects of ageing that precipitates a vicious cycle that furthers the decline of cell function and promotes ageing. This science has even led to a new term, inflammageing — the concept that low-grade inflammation drives many of the chronic diseases we associate with ageing, such as heart disease, cancer, diabetes, osteoporosis, and dementia. These diseases account for more than 70% of all deaths, and it would appear that they are impacted by lifestyle and environmental factors; meaning we can do something about it.
Parkinson’s, Pesticides, and the Environment
Let’s take Parkinson’s disease as an example. Another disease where the damage starts building in our 30's or 40s, and the first symptoms show up in our early 60s. While Alzheimer’s has long puzzled scientists, Parkinson’s has a clearer environmental link. Researchers believe that toxins in our air, food, and water are driving a large number of cases of this disease; not age nor genes, but our environment and lifestyle. Parkinson’s has been described as the price we pay for living in a ‘post-industrialised world.
This was supported in a major U.S. study, which recently found that people who lived near golf courses where pesticides are heavily used, contaminating the air and water, had a significantly higher risk of developing Parkinson’s. The risk dropped the further people lived from these courses. In Europe, where fewer pesticides are used on golf courses, this risk is lower.
This is a powerful reminder that our environment matters — and may be triggering inflammation and disease without us realising it.
So Why Are Women More At Risk For Alzheimer’s and Men More Parkinson’s?
That question still puzzles researchers. It’s not likely to be just environmental exposure, as women are exposed to toxins too, but possibly traditionally, less so. Women do develop Parkinson’s but it comes later in life than men, but when they do it progresses more quickly. Some scientists wonder if oestrogen plays a protective role against Parkinson’s when women are in their 30s and early 40s, with its anti-inflammatory and antioxidant properties helping to protect the brain cells responsible for dopamine production for longer. Later in life, as women enter perimenopause, oestrogen levels fluctuate wildly then drop, causing blood sugar levels to increase, leading to insulin resistance, damaging mitochondrial function (our cells energy power plants), leading to inflammation, weight gain, and an increased later-life risk for cancer, cardiovascular disease, Parkinson’s and Alzheimer’s disease.
These are still open questions, but one thing is clear, that chronic inflammation provides a more complete and useful explanation for the increased risk of Alzheimer’s disease women have, than age or gender alone.
The Brain’s Immune System: Friend or Foe?
Here’s how inflammation may work in the brain. The immune system’s job is to protect us, and that includes protecting the brain. When something harmful enters, like a bacteria or toxin, the brain’s immune cells respond. But in the case of Alzheimer’s, this response becomes chronic. Amyloid-beta itself may be part of this immune response, a kind of attempt to trap and remove invaders. But as the disease progresses, the immune system keeps attacking it, and the effects become toxic, increasing inflammation and harming healthy brain cells in the process.
This is the same kind of immune dysfunction response we see in autoimmune diseases like rheumatoid arthritis, and interestingly, autoimmune disorders also increase the risk for Alzheimer’s.
Your Gut, Your Brain, and Inflammation
Another important player in this story is the gut. Scientists now believe that the health of our gut microbiome, the trillions of bacteria living in our intestines, directly affects our health, by reducing inflammation in our body. These microbes produce substances that help regulate inflammation throughout the body, including in the brain. When we eat too much sugar and ultra-processed foods, take too many antibiotics, or are exposed to excessive amounts of environmental toxins, we can damage the microbiome and the integrity of the gut lining. This can eventually lead to a problem known as “leaky gut,” where contents of the gut seep into the blood stream causing inflammation which spreads throughout the body, even changing how the brain functions. On the other hand, a healthy diet will feed our beneficial gut microbes which leads to better overall physical and mental health.
In a Swedish study of 2,500 community-dwelling older adults, the researchers found that those who consistently ate a healthy diet developed chronic diseases more slowly than those who’s diets were considered highly inflammatory for the body, consisting of processed meats, high sugar foods and drinks and refined flour products such as white breads, pasta and cereals.
This is very important because most of the chronic diseases, such as heart disease, type 2 diabetes, cancer, stroke and depression are all strongly linked with Alzheimer’s, and delaying their onset will help to maintain cognitive function later in life.
And it’s not just the health of the bacteria in our gut that can impact cognition but more recently studies are finding that the composition of our oral bacteria can also increase our risk for cognitive decline. Periodontal disease is caused by a build up of unhealthy bacteria in the mouth, raising levels of inflammation and is associated with a six-fold increase in rates of cognitive decline.
So What Can We Do About It?
The best news of all is that chronic inflammation can be reduced, even reversed, with a handful of proven lifestyle changes. By seeing lifestyle practices such as sleep, diet and exercise as medicine, we can help avoid many or all of the chronic diseases that can come with old age, while building a brain resilient to cognitive decline.
These simple lifestyle practices include:
- Regular aerobic exercise - like brisk walking, swimming, dancing
- A healthy Mediterranean diet - or MIND diet, which supports brain health
- Good quality sleep - at least 7-8 hours a night
- Mental stimulation - new learning, reading, researching, playing music
- Social interaction - staying involved with others helps reduce stress and maintain cognitive function
- Mindfulness and stress reduction - proven to lower inflammation even in asthma and arthritis sufferers
- Avoiding added sugars and ultra-processed foods - will protect our gut and overall health
- Reducing exposure to environmental toxins - minimising exposure will reduce damaging chemicals in our blood and brain
- Nurturing your gut microbiome - by eating high-fibre foods like wholewheat, oats, apples, garlic, leafy greens, fruit and vegetables, we reduce brain inflammation and improve glucose metabolism.
- Maintain good oral hygiene- brushing your teeth twice daily and rinsing with warm salt water (avoid antiseptic mouthwashes as they kill healthy bacteria too). Have regular check-ups with your dentist.
Supplements and nutrients that support brain health and lower inflammation include:
- Omega-3 fatty acids (oily fish, flaxseeds, pecans, chlorella powder)
- Curcumin (from turmeric)
- Resveratrol (in grapes and berries)
- Catechins (from green tea)
- Vitamins B9 and B12, D, C, A, selenium, zinc, CoQ10
Start Small, Start Now
You don’t have to do everything at once. Trying to change too much, too fast, can backfire. If you eliminate sugar overnight, your cravings may spike. Eat too much fibre too quickly will cause excess gas, and your gut won’t be happy.
The key is small, steady steps. Add one or two healthy foods each week. Take a short daily walk. Try five minutes of mindfulness or deep breathing each morning. These changes add up and over time will compound resulting in overall better health.
Final Thoughts: A Call to Action
The rise in Alzheimer’s, Parkinson’s, and other brain diseases is not inevitable. It’s not just because we’re getting older, or because of bad luck. The real driver may be chronic inflammation which can accumulate as we age, something we can address through everyday choices.
The science is clear: over 80% of dementia cases may be preventable. But prevention doesn’t start at retirement, it starts in your 30s and 40s, with the food you eat, the air you breathe, how well you sleep, how active you are, how you handle stress and how you look after your general health.
We’re not powerless. We don’t need to wait for a miracle drug. The power to protect your brain and your future health is in your hands right now.
So ask yourself: What’s one thing I can do today to reduce inflammation in my body and protect my brain? Start there. Your future self will thank you.