Tangles in the brain’s navigational cells may explain why Alzheimer’s patients wander

Why do many Alzheimer’s patients wander? The culprit may be tangles of tau proteins in the brain’s navigational nerve cells, according to new research. It’s thought that those troubles with orientation start in a part of the brain called the entorhinal cortex, which houses excitatory grid cells that kick into gear as we move through space.

Here’s what researcher Karen Duff of Columbia University Medical Center said about the work, published in Neuron.

What do the grid cells do?

The grid cells are clumps of cells involved in setting the world and working out how we navigate in it from where the body is positioned. It’s part of the spatial navigation system along with other cell types. They are in a patch of the brain [the entorhinal cortex] which is highly affected very early on in Alzheimer’s disease. We traced the pathology in that area and looked at grid cell functioning.

What did you observe?

Mice showed deficits in cognition and also in spatial navigation — their ability to work out which direction to turn in a maze was challenged. When we looked at the patch of cells involved, we found that those cells were dysfunctional. That went along with having the tau [protein] tangles in that area of the brain.

The three things went together: the inability to navigate, the dysfunction of grid cells, and the location of these tangles in the same patch of cells.

Now we are interested in how we can fix the functioning of these cells. We’re also very interested in how this knowledge can be translated to better diagnose patients with the very earliest stages of Alzheimer’s.