Climate change is emerging as a growing threat to brain health, as rising temperatures and other environmental pressures add to the burden of neurological health conditions.
Neurological disorders, ranging from migraines to dementia and Parkinson’s disease, affect around one in three people over their lifetime, according to estimates cited by neurologist Ulf Kallweit, who is also a co-chair of the environmental influences task force at the European Academy of Neurology. Combined with mental health conditions, they accounted for an estimated global economic burden of €1.5 trillion in 2019.
“Everybody is somehow affected or knows somebody who is affected by a neurological disorder,” Kallweit told Euronews Health on the sidelines of the European Health Forum Gastein.
As climate change drives temperatures higher, the situation could deteriorate further, he warned, worsening existing conditions and potentially increasing the risk of developing neurological disorders.
But the trajectory is not inevitable. Policymakers can help limit the risks through measures that reduce exposure to heat and pollution and improve the environments in which people live.
Heat puts the brain under pressure
One of the clearest concerns is the relationship between high temperatures and stroke.
The number of stroke cases rises as temperatures climb above 30°C, Kallweit said, warning that heat-related strokes, which he said currently account for around 1% of all stroke cases, could represent 5 to 8% within the next 20 to 30 years.
Heat can also affect brain health indirectly by disrupting sleep.
Tropical nights, when temperatures remain above 20°C overnight, make it harder for the body to cool down. This can interfere with deep sleep and prevent people from recovering properly overnight.
“Everybody who experienced the last summer knows that sleep gets worse in these kind of heat nights,” Kallweit said.
Prolonged sleep disruption may have more serious consequences than a few restless nights.
“If you don't sleep well, not maybe one night, but for a longer time, there's a huge increase, let's say, for the risk of getting a stroke or also becoming demented,” he said.
Rising temperatures are also changing the geographical range of some infectious diseases, including those transmitted by ticks and mosquitoes. Some of these infections can affect the nervous system. Lyme borreliosis, for example, is transmitted by infected ticks and can cause neurological complications.
Malaria, meanwhile, remains a concern in discussions about the future spread of mosquito-borne diseases in Europe.
“Malaria is still not fully on yet there, but maybe in five or 10 years it may also affect us in southern parts of Europe,” Kallweit said.
Where you live matters
The risks are not shared equally.
Children, pregnant women, older people and those with pre-existing health conditions can be particularly vulnerable to extreme heat and other environmental pressures.
If they live in deprived neighbourhoods, their health risks rise further. Recent research has found that people living in socioeconomic deprivation have poorer indicators of brain health, including lower total brain volume and more signs of vascular damage.
Climate change could compound these existing inequalities.
“If you have heat and you cannot afford an AC, then you are more bothered,” Kallweit said. Access to healthy food, housing conditions and the surrounding environment can also shape people's health, he added.
Urban environments are particularly important. Noise, pollution and stressful living conditions can all affect wellbeing, while access to green spaces may offer some protection.
Therefore, improving access to green spaces is one potential way to support brain health.
“Going out to the forest one hour per week decreases your stroke risk by 3% or dementia risk by 4%,” Kallweit said.
Kallweit urged people to spend time in green surroundings and to protect their sleep by limiting exposure to light, noise and other disturbances.
But individual measures are only part of the answer. Public policy can help determine whether people have access to cooler homes, quieter neighbourhoods and cleaner air.
Kallweit called for safeguards against pollution and toxic substances, as well as changes to the way buildings are designed.
“How buildings are constructed should be reconsidered because they're still looking very much to the south, where the sun is entering,” he said, adding that such architecture “may be changed in the future.”