The U.S. military is funding research to understand the impact of brain lesions on pilots and its correlation to dementia-like cognitive impairments.
White matter hyper-intensities, also known as “high signal intensity areas” are associated with cognitive decline and milder forms of dementia in elderly people.
A study published in 2013 by Doctor Stephen McGuire of the University of Texas Health Sciences Centre found that American spy plane pilots had many more brain lesions than people with no altitude exposure.
A more recent study by the same researcher found that engineers operating altitude chambers present the same brain lesions. Altitude chambers are used to train pilots to recognise the effects of oxygen deprivation. Hypoxia causes disorientation and confusion leading to loss of consciousness.
Researchers agree that enough recovery time between flights is crucial to heal lesions. Twelve to 24 hours should suffice to prevent developing permanent lesions.
However, high altitude flying is not the only cause leading to brain lesions. Smoking, heavy drinking, high blood pressure, diabetes, and obesity are common risk factors.
Some people are more at risk than others. For example women are more likely to develop white matter hyper-intensities than men.
Long haul flights can be a challenge for many. A flight of six or more hours at an altitude our body is not used to may cause the onset of brain lesions.
At a typical cruising altitudes ranging between 11.000 to 12.200 metres (36 000 to 40 000 feet), air pressure in the cabin is pressurised at 1.800 to 2.400 metres (6000 to 8000 feet).
There are potential impacts of high altitude exposure on anyone with pre-existing neurological conditions who live at low altitude.
To make flying long distance more comfortable and safer passengers should keep well hydrated avoiding drinking alcohol, tea, and coffee. A stroll about the cabin every couple of hours is always recommendable.
No one knows you better than yourself. If you felt tired, disoriented or irritable you should inform cabin crew right away. People experiencing fatigue and disorientation should not rush to get off the airplane: an empty cabin is a friendlier environment to check if you have all your belongings.
Traumatic events like rapid or gradual cabin decompression may cause the onset of brain lesions. When cabin pressure decreases, passengers and crew are exposed to an increased risk of hypoxia, decompression, illness, and hypothermia. The higher the plane is flying, the faster crew must act to bring the aircraft to a safe altitude.
To prevent the onset of permanent brain lesions, frequent flyers belonging to one or more risk factor category should allow at least twelve hours between short haul flights and 24 between long haul flights.