Rising Heat’s Impact on the Brain
- As heatwaves become more frequent and intense, scientists are studying how extreme temperatures negatively impact both healthy and unhealthy brains.
Climate change has brought more intense and frequent heatwaves, and scientists are increasingly focused on how this affects our brains. These neurological impacts are particularly evident in individuals with pre-existing conditions. Jake, a young boy with Dravet Syndrome, provides a poignant example; his seizures are frequently triggered by high temperatures. According to his mother, Stephanie Smith, the sweltering heat of summer adds a significant burden to managing his condition. This family’s experience underscores a growing concern among neurologists and researchers.
Neurologist Sanjay Sisodiya of University College London has been at the forefront of this research. He noticed that his patients, many of whom have epilepsy, reported worsening symptoms during heatwaves. This led him to explore a wide range of neurological conditions affected by rising temperatures, including stroke, multiple sclerosis, and migraines. Sisodiya’s work highlights that the effects of heat on the brain are already a tangible issue. Data from both the 2003 European and the 2022 UK heatwaves show a direct link between extreme heat and a significant number of neurological deaths.
Why Our Brains Are So Vulnerable
The human brain is a highly sensitive organ that works hard to maintain a stable temperature. Despite being a major heat producer, its temperature typically stays within one degree Celsius of our core body temperature. Blood circulation helps regulate this, but extreme heat can overwhelm the system. When the brain overheats, the function of key neurotransmitter molecules can be disrupted, leading to communication breakdowns between nerve cells.
Sisodiya likens this to a clock where all the gears are no longer working in sync. While anyone’s brain function can be altered by heat, leading to poor decision-making and increased risk-taking, those with neurological conditions are often hit the hardest. In some cases, conditions like multiple sclerosis already impair the body’s ability to regulate temperature. Furthermore, certain medications used for conditions like schizophrenia can interfere with temperature regulation, making individuals even more susceptible to heatstroke.
Broader Public Health Implications
The impact of heat extends beyond specific neurological diseases. Elevated nighttime temperatures disrupt sleep, which can exacerbate conditions like epilepsy and depression. For older people, especially those with dementia, the risks are heightened due to both age-related thermoregulation issues and cognitive impairment. They may forget to drink enough water or avoid the heat, increasing their vulnerability.
Rising temperatures have also been linked to an increase in stroke-related incidents and deaths. A study analyzing stroke mortality data from 25 countries found that hot days contribute to thousands of additional stroke deaths globally each year. This problem is particularly acute in low- and middle-income countries, which bear a disproportionate share of the climate change burden. Additionally, extreme heat is associated with a higher rate of preterm births, which can lead to long-term neurodevelopmental problems in infants.
Future Concerns and Research
Scientists are also exploring other long-term consequences of a hotter world on the brain. Heat can make the blood-brain barrier more permeable, potentially allowing toxins, bacteria, and viruses to enter the brain more easily. This is a growing concern as rising temperatures expand the habitats of mosquitoes that carry diseases like Zika and dengue. The research is ongoing, with scientists still trying to pinpoint whether it’s maximum temperature, heatwave duration, or nighttime heat that has the most significant impact.
According to Sisodiya, the challenges currently faced by those with neurological disorders may become a reality for the general population as climate change intensifies. What we are seeing today may foreshadow a future where a “hot brain” becomes a more widespread public health issue.
