Hemodynamics in Alzheimer’s Disease and Vascular Cognitive Impairment and Dementia

Hemodynamic impairment is a prominent feature in aging, vascular cognitive impairment and dementia, and Alzheimer’s disease, including patterned changes in cerebral blood flow (CBF) that can be detected prior to concomitant pathologies. These CBF abnormalities drive vascular dysfunction through a variety of biological pathways and ultimately contribute to cerebrovascular disease associated with cognitive impairment. Importantly, the co-existence of cerebrovascular disease and Alzheimer’s disease is exceedingly common and worsens the progression of clinical symptoms, likely through accelerating neurotoxic protein deposition and the loss of cerebrovascular integrity. Emerging evidence further suggests that the brain may be more susceptible to subclinical cardiovascular dysfunction in aging adults, particularly since the accumulation of cardiovascular risk factors over the lifespan creates a more vulnerable vascular system. Although age-associated CBF dysregulation has varied and complex origins, it undoubtedly serves a critical role in the early progression of neurodegenerative disease and may help explain the considerable overlap between the most common clinical dementias.