Optics Of Alzheimer’s Disease

One of the hallmarks of Alzheimer’s disease is the formation of plaques made of protein aggregates in the brain tissue. There is still considerable debate among scientists as to whether these plaques are the cause of the neuronal death that occurs in Alzheimer’s or just a by-product of the disease, however.

In the last decade, autopsies have revealed that people with the worst dementia often don’t have the worst plaques, and clots and hemorrhages in small blood vessels have also been implicated in the disease.

New optical techniques may allow the link between altered blood flow and Alzheimer’s disease to be studied further by enabling scientists to directly look at the effect of clots in the brain’s microvasculature on the development of Alzheimer’s. Chris Schaffer and his colleagues at Cornell University use tightly focused femtosecond lasers to introduce clots in the microvasculature in the brains of rodents. The laser cuts open the cells lining the blood vessels, triggering natural clotting mechanisms and leading to the formation of an occlusion. The clotting process, as well as the subsequent changes in the brain, can be followed with fluorescence microscopy.

Schaffer and his colleagues are looking at whether putting tiny clots in the microvasculature can exacerbate Alzheimer’s disease. Using transgenic mice that are predisposed to developing early-onset Alzheimer’s disease, they have already shown that clotting a microvessel triggers the formation of new protein plaques. Next they plan to systematically study the effect of these clots on the cognitive decline of the Alzheimer’s mice.

Medical research is a cornerstone of Frontiers in Optics 2008 (FiO), the 92nd Annual Meeting of the Optical Society (OSA), being held Oct. 19-23 at the Riverside Convention Center in Rochester, N.Y. FiO 2008 will take place alongside Laser Science XXIV, the annual meeting of the American Physical Society’s Division of Laser Science. The presentation FTuE4, “Femtosecond Laser-Induced Microvascular Clots Trigger Alzheimer's Disease Pathology.”