How to avoid dementia: Keep your lungs strong and healthy

The surprising link between COPD and memory loss

You can live for several days without water and several weeks without food, but without the oxygen that enters your lungs, your life expectancy is no more than a couple of minutes.

You inhale oxygen and exhale carbon dioxide, a process carried out by around 280 million alveoli, the microscopic sacs at the end of the airways in your lungs. Those lungs do more than let you breathe: they are part of your immune system, forming a barrier against invaders.

Lung function, like everything else, is not always optimal. It is affected by diet, environmental factors, genes and ageing.

As part of the ageing process, there is decreased lung elasticity and muscle strength. There are also structural alterations in the alveoli. All these factors combine to create a gradual reduction in lung capacity and airflow. This makes you more susceptible to respiratory illness.

What’s more, if the oxygen supply is impaired in any way, you could also find that your memory is not what it was.

One respiratory illness that is becoming increasingly common is chronic obstructive pulmonary disease (COPD). COPD is the combination of bronchitis (persistent cough) and emphysema (destruction of the alveoli).

COPD is the fourth leading cause of death worldwide. It is estimated that globally 210 million people have the condition. In the UK it is the second most common lung disease, after asthma, with around 1.2 million people affected. In the US, 16 million people are affected, with 6.4% of adults diagnosed with COPD.

Once you have COPD you are at risk of developing other diseases, including lung cancer, heart problems, brittle bones, depression and dementia.

There are at least two ways that COPD links to dementia: inflammation and reduced oxygen flow.

COPD is an inflammatory condition, and in the same way that inflammatory substances from the gut can cross the gut barrier and enter the general circulation, inflammatory compounds in the lungs can seep into other areas of the body, leading to systemic inflammation.

One of those areas affected is the brain. Certain inflammatory compounds from COPD - IL-6, TNF-α, and IL-1β – breach the blood brain barrier and enter the central nervous system, and the result is neuroinflammation. This can damage neurons and their function, and contribute to cognitive impairment.

In addition to inflammation, there is also hypoxia, which is reduced oxygen flow. The combined effect of inflammation and hypoxia make COPD patients all the more susceptible to cognitive impairment. This impairment can be anything from mild to severe.

Tobacco smoking is a major cause, as is household air pollution, chemicals and fumes. These air pollutants come largely from fossil fuel combustion and industrial activities.

But whatever the underlying cause, the chances of developing the condition, and of it becoming more aggressive, are significantly increased where there is lack of certain key nutrients.

Nutrition plays a major role in the degree of severity of damage to the lungs. Many nutrients are involved, but there are three main players in pulmonary health.