Study Identifies Strong Connection Between Dopamine & Alzheimer's Risk
Alzheimer's disease impacts millions of people around the world, including at least 7 million in the United States, and that number is expected to grow in coming years. In the face of this threat, researchers are hard at work trying to understand—and treat—the degenerative condition.
The latest research is pointing to new pathways for treatment starting in the entorhinal cortex, which is often the first area of the brain affected by Alzheimer's. More specifically, researchers are looking at dopamine. The results were recently published in the journal Nature Neuroscience1. Here's what they found.
Studying the connection between Alzheimer's disease and dopamine
Before we dive into the methods of this research, let's start with a bit of context about the entorhinal cortex. Simply put, it's a brain region that connects the hippocampus and neocortex (the main part of the human brain), and it's essential for memory formation.
Researchers from the University of California, Irvine had previously discovered dopamine is essential for memory formation in the entorhinal cortex. They built on this research, and explored whether dopamine dysfunction contributed to memory impairment in Alzheimer's disease in this new study. They also went on to see if restoring dopamine function could improve memory.
Using a mouse model of Alzheimer's disease, the team observed that dopamine in the entorhinal cortex was significantly lower than normal. Namely, dopamine levels were reduced to less than one-fifth of what's considered normal, and neurons stopped responding appropriately, thus impairing memory formation.
Restoring dopamine levels for improved memory
To take their findings a step further, the team investigated how restoring dopamine levels in the brain might improve memory and learning. They increased the dopamine levels in the entorhinal cortex, and found that it restored the mice's ability to form memories.
The team also found that Levodopa (a drug for Parkinson's disease) improved memory and normalized neural activity.
"We did not initially expect dopamine to be affected in Alzheimer's disease," lead study author Kei Igarashi Ph.D. says in a news release. "However, as the evidence accumulated, it became clear that dopamine dysfunction plays a central role in memory impairment."
The takeaway
The findings of this study are groundbreaking to say the least. The more we can understand about the mechanisms underlying Alzheimer's disease, the better we'll be able to treat it. And based on this research, addressing dopamine levels in the entorhinal cortex could be one place to start.