The phrase "diseased brain" refers to a brain that is affected by some kind of illness or abnormality. It suggests that the brain is not functioning in a healthy or normal way, and may have problems or difficulties. Full definition
Peter Lansbury of the Center for Neurological Disease at Brigham and Women's Hospital in Boston agrees, and says the work lends credence to the theory that misfolded proteins, or prions, cause the fibers in diseased brains. (sciencemag.org)
Flashy neurons may get the attention, but a class of cells called glia are behind most of the brain's work — and many of its diseases (scientificamerican.com)
The hypothesis has been hotly debated for thirty years, since researchers showed that diseased brain tissue remained infectious even after treatment with radiation that would have destroyed any DNA or RNA. (uchospitals.edu)