Comparison between a healthy brain (left) and the brain of an Alzheimer's patient. Credit: Science History Images / Alamy Stock Photo.
Researchers analysing data from patients with a rare autoimmune disease, called cerebral amyloid angiopathy-related inflammation (CAA-ri), hope their work could help improve the understanding and treatment of Alzheimer’s disease.
CAA-ri is caused by antibodies that erroneously target a protein in the brain called beta-amyloid, that is naturally produced to stimulate cell growth but can also be toxic to nerve cells if not properly folded during synthesis. It is also the main component of amyloid plaques responsible for Alzheimer’s disease.
Among the symptoms of CAA-ri are some anomalies seen in magnetic-resonance imaging (MRI), that are very similar to the amyloid-related imaging anomalies (ARIA) that can be seen in some Alzheimer patients. In particular, ARIA is a frequent side effect of immune therapy for Alzheimer’s disease based on monoclonal antibodies, such as the recently approved aducanumab. This similarity led scientists to choose this rare inflammation as a potentially good model to study Alzheimer’s disease and improve the outcome of immunotherapy.
The study, by a team from Italy, Japan and Spain, involved 113 patients with CAA-ri, identified through the iCAβ International Network, a global initiative that includes 35 neurology clinic hospitals worldwide. After a MRI assessment confirmed the presence of ARIA, the patients were treated with high dose of corticosteroids, drugs that inhibit immune reactions. All patients were checked again after 3, 6, 12, and 24 months, revealing that 77% of them had completely recovered after 12 months. “Our study suggest that corticosteroids are effective in avoiding inflammatory relapses and in stabilizing patient recovery” says Fabrizio Piazza, a neurobiologist from the University of Milano-Bicocca and co-author of the study in Neurology1.
These findings could help ARIA developing in Alzheimer patients treated with immunotherapy, by combining that treatment with corticosteroids, and also improve the understanding of cerebral amyloid angiopathy. Further, the authors note that at least some degree of cerebral amyloid angiopathy is evident in almost all pathology studies on Alzheimer’s disease, suggesting that CAA-ri could be more common than originally thought. “It is possible that CAA-ri is part of a broader inflammatory phenomenon that is linked with Alzheimer’s disease” says Nicola Vanacore, head of the Monitoring Centre for Dementia, of the Italian National Institute of Health. “This is an example of research on rare events that has implications for much more common pathologies”.
