What is the correct term describing a group of disorders associated with degenerative changes in brain structure?

The correct term describing a group of disorders associated with degenerative changes in brain structure is 'neurodegenerative disorders'. These disorders are characterised by the progressive loss of neurons and their connections, leading to a decline in cognitive and motor functions. Examples of neurodegenerative disorders include Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS).