Symptoms Probably Started in the 1990s

Based on my experiences (dementia is in my family, and I know people who have relatives with it), there's this misconception that dementia suddenly springs up when you're diagnosed at 50, 60, 70, etc. However, dementia is an insidious disease that is the definition of "slow burn". It can take decades to unfold, but in such subtle ways that in its earlier stages it doesn't look anything more than normal personality change that come with age (mellowing out) or resembles more benign medical conditions (like B12 deficiency, anxiety, exhaustion, depression, etc.).

There's no question in my mind that Bruce Willis started having symptoms as early as the mid-nineties. The reason why I suspect as much is that there was a dramatic change in his onscreen presence from between his Moonlighting/Die Hard 1 and 2 days and Pulp Fiction/The Fifth Element. At the time, I just gave him the benefit of the doubt. Like, I remember how he was in Pulp Fiction and The Sixth Sense and thinking, "Okay, he's trying to change his acting style," or, "He was miscast or misdirected." However, the more I rewatched his performances over the years, the more vacant he came across.

Later on, people just trashed him, saying stuff like, "Oh, he's just lazy and phoning it in/taking a paycheck," but I don't think so. Even when charismatic actors do stuff to pay the bills, their personality comes through. If anything, they tend to play things more over the top, to let everyone know that they're in on the joke or have no respect for the material. For example, Nicolas Cage will always be his quirky, weird self no matter what he's in. But with Willis, it was like he was sleepwalking through his roles and the signature personality that had made him a star was gone.

In any event, dementia is a horrible, cruel disease, and part of the reason is that it makes the person look totally fine until it's progressed to the point of no return. So, until it's obvious that they have it (and get diagnosed), it just looks like someone being difficult, lazy, stupid, depressed, boring, etc.