The question of what causes complex neurological diseases such as Alzheimer's or multiple sclerosis continues to confound scientists and doctors, with the unknowns standing in the way of early diagnoses and effective treatments. Even among identical twins who share the same genetic risk factors, one may develop a particular neurological disease while the other does not. That's because unlike diseases such as cystic fibrosis or sickle-cell anemia, which are caused by a single gene, most neurological disorders are associated with many-;sometimes hundreds-;of rare genetic variants.
And on their own, these variants can't predict who will develop disease, as neurological conditions are also strongly influenced by environmental factors and vascular risks such as high blood pressure, aging, heart disease, or obesity. But there's one often-overlooked thread that connects most neurological diseases, says Katerina Akassoglou, PhD, a senior investigator at Gladstone Institutes: They're marked by a toxic immune reaction caused by blood that leaks into the brain through damaged blood vessels. "Interactions between the brain, blood vessels, and the immune system are a common thread in the development and progression of many neurological diseases that have been traditionally viewed as very different conditions," says Akassoglou, a senior investigator with the Gladstone Institute of Neurological Diseases and director of the Center for Neurovascular Brain Immunology at Gladstone and UC San Fr.
