Severe Type 2 Asthma Linked to Differences in Brain White Matter, Study Finds

People with severe type 2 asthma show measurable differences in brain structure compared with people whose asthma is well controlled. This is according to a study presented at the European Respiratory Society (ERS) Congress in Barcelona, Spain. The study was led by researchers from the NIHR Biomedical Research Centre Bristol and City St George's, University of London, in the UK. It suggests the inflammation driving severe asthma may affect more than the lungs.

Researchers scanned 50 people with severe type 2 asthma and compared them with 25 people with well-controlled mild or moderate type 2 asthma. They used magnetic resonance imaging (MRI) with a technique called quasi-diffusion imaging (QDI). QDI reveals the microscopic structure of white matter -- the brain's communication network that connects different regions and carries signals. People with severe asthma had less-organized white matter, and differences in hippocampus and temporal lobe size.

The degree of white matter change was linked to type 2 inflammation, the overactive immune response driving severe asthma. Dr. George Nava, NIHR academic clinical lecturer at the Bristol Academic Respiratory Unit, said higher inflammation was tied to greater white matter differences. "While this study cannot prove that inflammation causes these changes, it does suggest there may be a biological link that deserves further investigation," he said.

Researchers are now investigating whether these brain differences change after treatment targeting the inflammation. James Dodd, professor of respiratory medicine at the University of Bristol and chief investigator, said the team hopes its work will show whether the changes can be prevented or reversed.

Dr Apostolos Bossios, head of the ERS Assembly on Airway Diseases, Asthma, Chronic Obstructive Pulmonary Disease (COPD) and Chronic Cough, was not involved in the research. He is an associate professor of respiratory medicine at the Karolinska Institutet in Sweden. Bossios said type 2 asthma is the most common asthma phenotype and that about 5% to 10% of patients develop severe disease.