{"id":360432,"date":"2019-01-25T16:06:40","date_gmt":"2019-01-25T21:06:40","guid":{"rendered":"http:\/\/www.rochester.edu\/newscenter\/?p=360432"},"modified":"2023-06-13T11:26:24","modified_gmt":"2023-06-13T15:26:24","slug":"study-suggests-how-high-blood-pressure-might-contribute-to-alzheimers-360432","status":"publish","type":"post","link":"https:\/\/www.rochester.edu\/newscenter\/study-suggests-how-high-blood-pressure-might-contribute-to-alzheimers-360432\/","title":{"rendered":"Study suggests how high blood pressure might contribute to Alzheimer\u2019s"},"content":{"rendered":"

The brain\u2019s system for removing waste is driven primarily by the pulsations of adjoining arteries, Ä¢¹½´«Ã½ neuroscientists and mechanical engineers report in a new study. They also show that changes in the pulsations caused by high blood pressure slow the removal of waste, reducing its efficiency.<\/p>\n

This might explain the association between high blood pressure and Alzheimer\u2019 disease, the researchers say. Alzheimer\u2019s, the most common cause of dementia among older adults, is characterized by abnormal clumps and tangled bundles of fibers in the brain.<\/p>\n

The study, reported in Nature Communications<\/em><\/a>, builds upon groundbreaking discoveries about the brain\u2019s waste removal system by Maiken Nedergaard, co-director of the University\u2019s Center for Translational Neuromedicine<\/a>. Nedergaard and her colleagues were the first to describe how cerebrospinal fluid is pumped into brain tissue and flushes away waste. Subsequent research by her team has shown that this glymphatic waste removal system is more active while we sleep and can be damaged by stroke and trauma.<\/p>\n

This latest research shows \u201cin much greater depth and much greater precision than before\u201d how the glymphatic system functions in the perivascular spaces that surround arteries in the outer brain membrane, says Douglas Kelley, an assistant professor of mechanical engineering<\/a> and an expert in fluid dynamics. His lab is collaborating with Nedergaard\u2019s team as part of a $3.2 million National Institute on Aging grant.<\/p>\n

\"illustration
In the left panel, superimposed particle tracks reveal that cerebrospinal fluid flows through wide perivascular spaces, which are approximately as large as the adjacent artery. Averaging together hundreds of thousands of measurements produces a velocity field, shown in the green arrows in the right panel, which demonstrates that the net cerebrospinal fluid flow is in the same direction as the blood flow. (Ä¢¹½´«Ã½ illustration \/ Jeff Tithof)<\/figcaption><\/figure>\n

For this study, Humberto Mestre, a PhD student in Nedergaard\u2019s lab, injected minute particles in the cerebrospinal fluid of mice, and then used two-photon microscopy to create videos showing the particles as they moved through the perivascular spaces.<\/p>\n

Jeff Tithof, a postdoctoral researcher working with Kelley, then used an automated particle tracking code developed by the Kelley lab that can follow a dot from frame to frame of a video, and after a few frames estimate its velocity and acceleration. From a typical video spanning \u201ctens of minutes,\u201d the code could track more than 20,000 individual particles and derive about a million total measurements to quantify their movements, which show up as \u201ccomet tails\u201d behind each of the tracked dots in the videos.<\/p>\n

By analyzing videos from experiments involving multiple mice, \u201cwe were able to gather a really rich data set of what\u2019s actually happening with this flow,\u201d Kelley says.<\/p>\n

The researchers found that:<\/p>\n