Does aging affect Alzheimer’s or negatively change the brain?

When you look at a brain that ages, without any dementia, there are changes in the brain and there’s a cognitive decline in some. But again, there’s individual variability similar to the stress response. We were trying to find what would be the early things in the brain that would later have to do with cognitive decline, and what we learned is that it has to do with vascular function. There’s vasculature in the brain, and there’s a big demand for blood, glucose, and oxygen in the brain so that vasculature is very rich and it has the blood-brain barrier. Every vessel in your brain has this barrier of a layer of cells to keep it isolated so that things from the blood can’t just spill into the brain. Pretty early on in aging, we see a decrease of this blood-brain barrier and we see this deterioration begin in the hippocampus, in both animals and humans. We followed what happens when some blood proteins get into the brain, where they activate a signaling cascade in cells that aren’t the neurons, but rather other cells called astrocytes, activating an inflammatory response. There’s no pathogen, yet the brain reacts with a big inflammatory response that changes neurons that causes cognitive decline, and also cell death which adds to neurodegeneration.