Cluster headache causes extreme pain, but its origins remain unclear. New research links the disorder to genetics, inflammation, and tobacco smoke exposure.
Unlike an ordinary headache, a cluster attack typically erupts without warning and causes excruciating pain around one eye. Episodes can last from 15 minutes to three hours and often return at similar times each day. The severity of the condition has led to its troubling nickname, the “suicide headache.”
Scientists have long suspected that both genes and environmental exposures contribute to cluster headaches. Two studies from Karolinska Institutet in Sweden have now examined those influences from different angles, revealing signs of inflammation, altered gene regulation, and increased exposure to toxic substances.
Cluster Headache Genes Point to Inflammation
The first study built on genetic risk regions discovered through genome-wide association studies (GWAS), which search the genomes of people with and without a condition for meaningful differences. Researchers analyzed genetic information from more than 1,500 people, then examined blood, skin cells, and DNA from smaller groups of patients and healthy controls. The findings were published in The Journal of Headache and Pain.
The investigation strengthened the evidence for seven genes previously connected to cluster headache. Several showed different patterns of activity in people with the disorder, suggesting that the genetic associations have measurable effects within the body.
Six of the seven genes either function in immune cells or participate in inflammatory signaling. Rather than implicating a single isolated gene, the results suggest that several genetic risk factors may converge on related biological pathways.
“This strengthens the hypothesis that the immune system and inflammation may play a central role in cluster headache,” said Caroline Ran, associate professor at the Centre for Cluster Headache in the Department of Neuroscience at Karolinska Institutet. “Several of the genes influence the same biological signaling pathways, which provides us with important clues about the mechanisms behind the condition.”
Tobacco Smoke Leaves Molecular Traces
A second study, published in Cephalalgia, investigated a possible environmental influence. Because smoking is more common among people with cluster headaches than in the general population, researchers looked for biological signs of exposure to substances carried in tobacco smoke.
The team studied blood, DNA, and cerebrospinal fluid from patients and healthy controls. Sample sizes ranged from 26 to 79 people depending on the analysis, reflecting the difficulty of conducting detailed biological research on a rare disorder.
People with cluster headaches had markers associated with greater exposure to heavy metals and other tobacco smoke components. They also showed differences in markers related to DNA methylation, a chemical process that helps regulate gene activity without changing the underlying DNA sequence.
“This study cannot prove cause and effect, but the results suggest that environmental factors, such as heavy metals in tobacco smoke, may interact with biological mechanisms in cluster headache,” said Andrea Carmine Belin, associate professor at the Centre for Cluster Headache in the Department of Neuroscience at Karolinska Institutet.
Important Clues, but Not Proof
Together, the studies suggest that cluster headache may involve more than the brain’s pain circuits alone. Immune signaling, inflammation, environmental exposure, and the molecular controls governing gene activity could all be part of a broader biological network associated with the condition.
Larger studies will be needed to confirm the results and clarify how the genetic and environmental signals fit together. If replicated, however, the findings could help researchers identify biological pathways worth targeting in future diagnostic tools or treatments.
References:
“Genome-wide association susceptibility loci for cluster headache support a role for inflammation in the pathophysiology” by Caroline Ran, Clémence Deborgies Sanches, Julia Swedblom, Katrin Wellfelt, Alessandro Antoniazzi, Joseph Lloyd, Felicia Jennysdotter Olofsgård, Stefan Spulber, Elisabet Waldenlind, Maria Lantz, Anna Steinberg, Anna Sundholm, Christina Sjöstrand and Andrea Carmine Belin, 4 August 2026, The Journal of Headache and Pain.
DOI: 10.1186/s10194-026-02485-x
“Increased markers of heavy metal exposure and DNA methylation in cluster headache” by Joseph Lloyd, Katrin Wellfelt, Felicia Jennysdotter Olofsgård, Clémence Deborgies Sanches, Anna Steinberg, Anna Sundholm, Caroline Ran and Andrea Carmine Belin, 1 August 2026, Cephalalgia.
DOI: 10.1177/03331024261480707
Funding for the research came from the Mellby Gård Foundation, the Swedish Brain Foundation, Region Stockholm, the Swedish Research Council, the International Headache Society, and the Swedish Headache Society, among others.
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