A lay summary written by Natalie Pye and reviewed by Dr Ryan West.
Background
With age our lungs function less well, and our body gets less oxygen in our blood. Growing evidence suggests that poor airways and lung health, is linked to a decline in our brain function and may increase our risk of dementia. However, it is still unclear how poor lung health and function and decline in brain function are associated.
Why is the study important?
Long term studies allow us to see how our bodies change over time and how this may lead to a decrease in brain function and onset of dementia. Understanding the changes in our body that may lead to dementia is vital for finding opportunities to intervene before onset of the disease.
What did the authors do and how did they do it?
Over a period of 21 years, 1377 participants with no symptoms of dementia at the start of the study, were assessed annually for their lung function by blowing into a small device to test how fast and how much air they could breathe out.
The participants also completed a series of tests for general brain function, memory, and perception, such as remembering a list of words or completing a pattern. 351 of the participants also had an MRI scan, which allows the scientists to produce images of inside the brain from outside our bodies and measure the size of different parts of the brain.
The authors analysed the changes in lung function over time and how this may relate to changes in brain function and brain size.
What are the results?
The authors found that poor lung health and function was associated with a faster decline in general brain function, memory, and perception. Additionally, they found that participants with the poorest lung health had significantly smaller sized brains than participants with good lung health. This data suggests that poor lung health may be an important factor in the risk of dementia.
What do the finding mean going forward for people with the disease?
The findings implicate the importance of good lung health on the brain and suggest that treatments to maintain lung health may be an opportunity to prevent decline in brain function and risk of dementia in later life.
The authors suggest testing lifestyle changes, such as more exercise or stopping smoking, in older adults to see if improving lung health can improve brain function or delay the onset of dementia.