Our immune system is more susceptible to chronic inflammation as we age - our Research Scientist's insight into inflammation and dementia.
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Back in the 1950s, scientists noted with surprise that heart disease was far less common in Mediterranean countries than in the U.S.
And knowing that what’s bad for your heart is bad for your brain, a spate of research ensued that found these communities had lower rates of dementia and many other age-related conditions as well.
Why? Well, a lot of it is - strangely - down to your immune system.
When your immune system encounters a threat such as illness or injury, it triggers the release of chemicals to fight that threat in a process called inflammation.
When the threat has been neutralised, the immune system effectively turns this process off.
However, if your immune system fails to turn off this response, these chemicals can start to attack healthy cells and organs, and you start to see damage over time.
Because as we age, our body finds it harder and harder to turn off this immune response, and chronic inflammation increases, in a process known as inflammaging.
This means your immune system is in a state of constant activation, even in the absence of acute infection or injury.
This type of inflammation can linger in the body for long periods of time without presenting any obvious symptoms.
By the time it does present symptoms, these might look like chronic pain, depression, fatigue, and a weakened immune system.
In a way, some of these symptoms make sense if you think about how the immune system has evolved. When people are unwell, for example with a cold, they can become lethargic and withdrawn. This is a phenomenon called sickness behaviour, which scientists think has evolved to force a person to take time to rest, keep their head down low to avoid conflict, and ideally to avoid spreading pathogens to others in the group.
Inflammation-induced sickness behaviour is increasingly being seen as relevant to understanding some cases of depression.
While low-grade inflammation might not seem like a big deal, it can have serious consequences for your health. Inflammaging is linked to several age-related diseases like heart disease, type 2 diabetes, and even certain types of cancer.
And importantly for brain health, this process can ultimately contribute to cognitive decline and dementia.
In short, inflammaging basically accelerates the processes of normal biological ageing.
Diet has a direct influence on inflammation and can reduce inflammaging.
This is because gut health and inflammation are intimately related. Gut microbiome diversity decreases with age. Furthermore, certain types of “good” bacteria, which play an anti-inflammatory role in the gut microbiome, decline with age, allowing inflammation to increase.
On the other hand, bad bacteria increase with age and promote inflammation and disease!
Our article on eating the rainbow discusses ways to increase your gut microbial diversity. Learn more about how the gut and the brain are intricately connected with our handy primer.
If you’re looking down at your plate and it’s all one colour (likely beige), you’re looking at the standard Western diet, which is low in variety, and typically high in animal fat and protein and low in fibre.
This diet is associated with increased production of cancer-causing compounds and inflammation.
The brain-healthy Mediterranean diet, on the other hand, is more diverse and includes a range of plants. It’s high in fibre, which has been found to have anti-inflammatory effects and improve the immune system, and low in red meat. The Mediterranean diet has been shown to reduce inflammation in older adults.
We talk about waist size a lot at Five Lives. It’s super important. And something that isn’t quite captured by typical health measures such as the body mass index.
That’s because the larger your waist size, the more belly fat you have, and in particular, visceral fat. This fat lives around your organs and is different from the “subcutaneous” fat that sits under the skin. Visceral fat is more likely to pump out inflammation-causing hormones and toxins.
Aerobic activity (such as brisk walking) and strength training (exercising with weights) have both been shown to cut back visceral fat.
Stress is one of the biggest drivers of inflammation - in fact, we see this over and over again in the research.
Mind-body interventions (like mindfulness meditation, yoga and tai chi) seem exceptionally effective at tackling inflammation. A review of eighteen studies concluded that these interventions seem to “turn off” genes that cause inflammation when we’re stressed out.
Medical low-down
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