Alzheimer's disease: more than amyloid

The etiology of Alzheimer's disease (AD) is inconclusive. Treatments targeting amyloid have largely been unsuccessful. There is increasing evidence that vasculopathy may play an important pathogenic role in AD.

Longitudinal measurements of whole blood viscosity (WBV) using a computer-assisted hemorheologic protocol and characterization of microvascular abnormalities using computer-assisted intravital microscopy (CAIM) are two objective methods adopted in this laboratory to noninvasively quantify vasculopathy in AD patients. A correlation of increased disease severity with worsened vasculopathy would further bolster a cause and effect relationship. A case report (Case 1) is presented to illustrate the usefulness of following an AD patient with these noninvasive techniques to correlate disease progression with vasculopathy.

Patients were selected from a private practice setting who met the Diagnostic and Statistical Manual of Mental Disorders criteria for AD. The Rheolog™, a computer-assisted scanning rheometer, was used to obtain longitudinal measurements of WBV. The microvascular abnormalities in the bulbar conjunctiva were quantified using a severity index (SI, scale 0-15). The patient was observed over a 4 year period from 2005 to 2008.

This case study shows a correlation of disease progression in an AD patient with worsened vasculopathy. It illustrates the usefulness of WBV and CAIM as tools to quantify vasculopathy in AD patients and additionally suggests a pathogenetic role vasculopathy may play in concert with the amyloid hypothesis.