What, physically, is a memory?

A retired internist's guide to what a memory is, how the brain keeps it, how it changes, and what to do when it starts to slip.

Four Digits: A Physician's Guide to Memory. Book One of The Watchman Series

In 1975, in a college psychology class, strings of digits were flashed on a screen and the class was asked to repeat them. A pre-med senior with three years of chemistry behind him could hold four. The girl sitting in front of him held twelve. He went on to practice internal medicine for four decades. She became his wife. And he never stopped wondering what, physically, a memory is.

Four Digits is his answer, in eight short lectures built on the science and on the patients he cared for: what a memory is in the brain and where it is kept; why sleep decides what you keep; why a memory changes a little every time you recall it, and why a confident eyewitness can be wrong; what normal aging takes and what it leaves alone; how Alzheimer's disease begins, and what the new blood test for it (p-tau217) can and cannot tell you; and the causes of memory loss that can be reversed.

It ends with a five-word test you can give yourself at the kitchen table, and with when to take the result to your physician.

The Watchman Series is a set of books on the questions medicine is still answering. Four Digits is the first; more are in progress.

Coming soon on Kindle and in paperback. The Lighthouse Watchman Press