Cognitive Decline Associated with Aging, Alzheimer’s Disease and Cerebrovascular Risk: Advantages of Dynamic Imaging with MEG

Recent studies examining Alzheimer’s disease (AD) and aging have noted a strong association between cerebrovascular risk and cognitive decline, and suggest that AD may in part be attributed to vascular insufficiency. Based on our recent results we suggest that cognitive decline associated with cerebrovascular pathology should be characterized and if possible separated from neurodegeneration caused by amyloid plaques and neurofibrillary tangles (i.e., traditional AD-related pathology) since the progression of cerebrovascular pathology can be stopped or slowed down. Furthermore, because cerebrovascular pathology (e.g., hypertension and type 2 diabetes) co-exists in most AD patients, neuroimaging techniques dependent on ‘uncompromised’ neurovascular coupling (e.g., fMRI) will have more potential confounds to deal with in this area of study, in addition to difficulties associated with being an indirect measure of neural activity. We assert that functional measures (e.g., dynamic cortical networks, oscillatory activity and cross-frequency coupling), as opposed to structural measures (e.g., diffusion tensor imaging–DTI), will enable earlier diagnosis of AD and mild cognitive impairment (MCI) and that MEG in particular can make important contributions to this field. A new potential area of study that relates MEG single trial results to models of diffusion parameters in extracellular space is introduced.