Changes in the amount of blood being delivered to different brain areas may be one of the earliest factors associated with late-onset Alzheimer’s disease, according to a paper published in Nature Communications.

Late-onset Alzheimer’s disease - the most common form of human dementia - is not causally associated with any unique mechanism but rather with multiple factors which are thought to co-occur. The idea that blood flow disruptions may contribute to Alzheimer’s disease has been around since the early 1900s, and studies investigating disease progression in mice have reported early changes in brain blood flow.

Using a multi-factorial approach, Yasser Iturria Medina and colleagues compared brain imaging data, blood plasma and cerebral spinal fluid (CSF) samples from a database comprising 1,171 healthy and disease-affected individuals. The authors divided participant data based upon the severity of their diagnosis - from healthy controls, to early or late mild cognitive impairment, to Alzheimer’s disease - in order to track disease progression. Out of the many factors investigated, blood flow was one of the first to show changes during disease progression, with abnormalities seen across all brain regions and time points. Comparison of blood plasma and CSF samples found differences in a number of proteins linked to vascular regulation (such as Apolipoprotein A and IP-10) at different points of disease progression, although it is not clear whether these proteins are contributing to vascular changes in the patients.

These results show a correlation between changes in blood flow and disease progression, but further studies are required to determine if and how changes to brain blood flow may be contributing to disease progression.