Insights into cognitive aging and Alzheimer’s disease using amyloid PET and structural MRI scans

Positron emission tomography using amyloid binding ligands, labeled with carbon-11 and fluorine-18, (Amyloid PET) has been used to understand the relationship between amyloid deposition in the brain, neurodegeneration and the development of mild cognitive impairment and dementia. Structural MRI has been used to identify morphological changes in the brain which may relate to the cause(s) of cognitive impairment, including infarcts, space-occupying lesions, hydrocephalus and the patterns of atrophy which are characteristic of various neurodegenerative diseases. These two imaging biomarkers have also played an important role in revealing the sequence of cerebral amyloid deposition, neurodegeneration and cognitive impairment. Although there may not be a direct relationship between amyloid deposition and brain atrophy or cognitive deficits, the presence of both amyloid deposition on PET and neurodegeneration on MRI has been associated with accelerated cognitive decline. The main focus of this article is to summarize some of the insights gained using these two imaging methods individually and in combination to better understand the biological bases of normal aging and age-associated cognitive impairment