Stroke (中风) is a leading cause of death and disability worldwide. You may be familiar with some of the most common lifestyle and health factors that could affect your stroke risk. However, there is another overlooked factor—altitude.

How can living at high altitudes affect your chance of suffering a stroke? This question is at the heart of a new study in journal Frontiers in Physiology. The study examined more than 100,000 stroke hospitalisations and deaths from between 2001 and 2017 in Ecuador. The researchers assessed levels of stroke hospitalisation and death among people living at four different elevation ranges: low altitude (under 1,500 metres), moderate altitude (1,500-2,500 metres), high altitude (2,500-3,500 metres) and very high altitude (3,500-5,500 metres).

The results showed that people who lived at higher altitudes (above 2,500 meters) tended to experience stroke at a later age compared with those at lower altitudes. They were also less likely to be hospitalized or die because of stroke. However, this protective effect was the greatest between 2,000 and 3,500 meters and tailed off a little above 3,500 meters.

So, why might living at high altitudes protect against stroke? It may be that people who live at high altitude have adapted to the low oxygen conditions, and more readily grow new blood vessels (血管) to help overcome stroke-related damage. They may also have a more developed network of vessels in their brains that helps them to make the most of the oxygen they take in.

More research is needed to identify the mechanisms behind this phenomenon, but the results may be some comfort to those who live on top of the world.

New research has found that people with mild cognitive impairment (认知损坏) may not necessarily develop dementia (痴呆) and, in fact, having higher education and advanced language skills more than doubles their chances of returning to normal.

The study, led by researchers at the University of Waterloo, may reassure those with mild cognitive impairment as it contradicts a common assumption that the condition is simply an early stage of dementia. People with mild cognitive impairment show signs of cognitive decline, but not enough to prevent them from performing typical daily tasks. They have been considered at higher risk of progressing to the more severe cognitive decline seen in dementia.

“Possessing high cognitive reserve, based on education, high academic grades, and written language skills, may predict what happens years after someone receives a diagnosis of mild cognitive impairment,” said Suzanne Tyas, a professor in the School of Public Health Sciences at Waterloo and lead author. “Even after considering age, genetics and established risk factors for dementia, we found that higher levels of education more than doubled the chances that people with mild cognitive impairment would return to normal cognition instead of progressing to dementia.”

The study’s findings have meanings for treatment and research in people with mild cognitive impairment.

“If individuals with higher cognitive reserve are more likely to improve even without treatment, then this needs to be taken into consideration when recruiting participants for clinical trials of prospective treatments and when interpreting the results of these trials,” Tyas said, adding there’s no cure for most causes of dementia, so prevention is key.