Life course of the brain during normal aging and Alzheimer's disease

Published on May 31, 2016   36 min

Other Talks in the Series: Aging

0:00
I'm Caleb Finch. I'm a Neurobiologist, PhD at the University of Southern California. My talk will be on the life course of the brain during normal aging and Alzheimer's disease. And I hope to bring to your attention changes that begin relatively early and are benign, as they are understood and may progress in some individuals to the devastating endpoints of Alzheimer's disease.
0:28
The next slide shows truly remarkable woman, unique in her lifespan of 122 years and unique also in reaching that advanced age with a few, if any signs of mental deterioration. This is Jeanne Calment and there is no one who has approached her lifespan since. The sad fact is that about 50% of centenarians are mentally impaired.
0:59
The next slide shows the devastating reality that after the age of 60, in all human populations, the risk of Alzheimer's increases exponentially. The risk doubles every five years after the age of 60 and that curve has a horrible prediction that if you live long enough, you'll get Alzheimer's. This is obviously not the case, for some individuals seem to be protected. We want to understand that.
1:32
The three larger processes that are ongoing with aging, the best understood is Infarcts or blood clots in the brain that happen at some degree of randomness in different parts of the brain and are associated with hypertension. They are also on a much smaller scale in some people and those are called micro infarcts. And of course, the familiar extreme is stroke. This is a process that is added onto two other processes that are concurrent in almost everyone. The largest red circle is primary Neuro-degeneration, which arises during Alzheimer's disease and Parkinson's. And then intersecting as a risk factor is damage to the white matter, the myelin of our brain, which has many different causes.
2:33
The most obvious manifestation of Alzheimer's disease is atrophy of the cerebral cortex in which nerve cells have died grossly and synapses are lost. At the end of the day, the loss of synapses is the most critical part in Alzheimer's disease and in aging because it reduces the ability of nerve cells to talk with each other.
3:01
Brain aging really begins relatively young in our life. There is a slow degree of atrophy of the cerebral cortex, loss of synapses, accumulation of the brain protein amyloid and at the same time, the outcome of this is slightly slower processing of information and slight reductions of memory that everybody recognizes. When they get to be 50, they don't have as fast thought process as at 30. There are many different pathways of brain aging and we understand very little about why individuals, even identical twins, have such different outcomes of brain aging. Another mystery is that there are some elderly who have clinical grade pathology post-mortem but were cognitively normal until the end of their lives. So we have a huge number of scientific questions that are unanswered and that are being studied in labs across the world. Let's look in a little bit more detail about the processes that are ongoing from the age of 30 onwards.
4:17
The next slide shows a modern brain imaging technology that identifies in the red areas and the bottom row, the regions that are most damaged in Alzheimer's disease. But many of these are also undergoing a subtle, milder changes during normal aging. So essentially, we have to recognize that aging is a slow process of atrophy in the brain and it can be quantified and looks pretty much like a linear slope of loss of synapses and thinning of our brains at about a half a percent to 1% per year.
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Life course of the brain during normal aging and Alzheimer's disease

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