Heatwaves may increase likelihood of seizures in people with epilepsy
New research has shown that abnormal excitability of the brain in people with epilepsy can worsen during heatwaves. This is some of the first evidence to demonstrate the vulnerability of people with epilepsy to the higher temperatures of climate change.
The new small-scale patient study led by Epilepsy Society’s Director of Genomics, Professor Sanjay Sisodiya, used intracranial EEG (icEEG) tests to track the brain activity of nine people with drug-resistant epilepsy who were being evaluated for surgery during the summer months – May-August - of 2015-2022.
icEEG involves inserting electrodes into the brain to measure electrical impulses. All the people were being assessed at the National Hospital for Neurology and Neurosurgery, and genomic tests had shown that none of them had known genetic epilepsies that are already associated increased seizure activity during heatwaves.
Surgical assessment during heatwaves
The nine patients involved in the study were, by chance, having icEEG recordings taken during spontaneous heatwaves in London, allowing the researchers to directly examine their brain activity during periods of unusually hot weather.
In London, a heatwave is defined as three or more consecutive days with daily maximum temperatures of more than 28 degrees Celsius.
The researchers – all clinical scientist from UCL - then compared this patient data to icEEG recordings taken from the people during non-heatwave periods – while ensuring that all other conditions (apart from temperature) remained the same.
For each participant, the team logged any abnormal electrical activity across four 10-minute segments within and outside of heatwaves. They also tracked all seizures.
They found that, overall, more seizures were recorded by the icEEG during heatwaves compared with the non-heatwave period. Meanwhile, three patients also had more abnormal electrical brain activity aside from seizures during heatwaves.
The results were published in Brain Communications.
First evidence of link between heat and epilepsy
Professor Sanjay Sisodiya said: “Our research shows that for some people with epilepsy – in particular those with the most severe epilepsies – higher ambient temperatures increase the likelihood of having seizures.
“This is an important finding, providing some of the first evidence that for some people who already have epilepsy, higher temperatures seen during heatwaves can make their condition worse.
“Such information is important for the care of individual people with epilepsy, and also for broader efforts to ensure people with epilepsy can be kept safe as the climate changes.”
The current study sample size is relatively small as icEEG is not commonly undertaken and a heatwave had to have happened, by chance, during the recording.
However, the team now hope to have a bigger prospective study, and data is currently being collected.
Climate change can affect brain health
Professor Sisodiya said: “Despite the study’s limited sample size, our findings remain valuable in the context of climate change. As global temperatures rise and extreme weather events become more frequent, understanding the effects of heatwaves on brain activity is crucial.”
Professor Sisodiya recently led a review of 332 papers published across the world, that explored that scale of potential effects of climate change on neurological diseases*.
The researchers found that the effect of climate change on weather patterns and adverse weather events is likely to negatively affect the health of people with brain conditions, including stroke, migraine, Alzheimer’s, meningitis, epilepsy and multiple sclerosis. The new research adds to this analysis.
The research was carried out in collaboration with researchers at UCLH and funded by the Epilepsy Society, The Amelia Roberts Fellowship, and a UCL Grand Challenges Climate Crisis Special Initiative award.