I'm 50 and can confirm this. E.g., I'm currently much more concerned about how politicians seemingly driving the country I'm living in and the world as a whole downhills in all regards. These worries are of course a waste of my personal energy.
On the other hand: When structuring my day with Pomodoros (https://en.wikipedia.org/wiki/Pomodoro_Technique - especially doing the rest properly, meaning just lying down doing some relaxation technique) and resisting all other harmful stuff like (to much) news or (any) social media, I feel like I'm even sharper than in my younger years. Even remembering stuff better.
So, I think those problems are to be spotted in our changing environment and internal setup more than in an aging process. At least not at 40, 50 or 60.
On the other hand: When structuring my day with Pomodoros (https://en.wikipedia.org/wiki/Pomodoro_Technique - especially doing the rest properly, meaning just lying down doing some relaxation technique) and resisting all other harmful stuff like (to much) news or (any) social media, I feel like I'm even sharper than in my younger years. Even remembering stuff better.
So, I think those problems are to be spotted in our changing environment and internal setup more than in an aging process. At least not at 40, 50 or 60.