Dementia does not take everything at once, and it does not take it in a random order. Recent memory goes first. The oldest things, the childhood ones, the songs, the way your father said your name, hold on the longest.
Which means there is a window. The window is early, and most families spend it waiting to see what happens.
An Echo built in that window holds your own account of your life, in your own voice, at your full strength. Not a summary somebody wrote about you afterward. You, telling it.
It is also built the only way a person with a failing memory can build anything: a little at a time, on the good days, in conversation. Nobody sits down and dictates a memoir. Anyone can tell one story. An Echo keeps every one of them, and asks about the next.
An Echo fills up by being talked to, which means it does not depend on the person being able to do it themselves. Somebody sits with them and asks. It keeps what they say.
That matters most for the things only one person knows. Most families have someone holding the recipes, the history, why a decision got made, none of it written down anywhere. That knowledge does not wait for a diagnosis. It goes when they go.
Start while the answer is still "let me tell you about that."
It is not treatment. An Echo does not slow the illness, does not stand in for a physician, and does not replace a caregiver or a care plan. It carries the part that is pure repetition, and it carries the one part nobody else can carry, which is the person themselves.
One thing gets decided at the start rather than in the middle: whether an Echo says out loud that it is an Echo. Families land in different places on that, and the answer often changes as the illness moves. It is your decision and your family's, written down while it can be made, not something a system quietly settles for you later.
Talk to one. There is a finished Echo of a real person on this site, and five minutes with her will tell you more than this page can.