Did you ever go out to the car and forget what it was you were going to look for? Or go into another room and forget why you were there? Or think of a website you wanted to visit, and by the time you'd checked your email you had forgotten what site you were interested in?

Yeah, me too.

I would say it's a phenomenon of old age and forgetfulness, but to tell you the truth, I've been like this I would say forever. Partly the forgetfulness is due to my thinking about something else between the two events (from one room to another).

But also there is a psychological factor of which we may not be aware. It's the shifting of frames of reference. When you're in one room, say the kitchen, that's your frame of reference. You think of a book you wanted to read, so you go into the living room and by stepping through the doorway, your brain re-sets the frame of reference--and you forget what you had set as your goal when you were in the kitchen. You wonder if you're losing it.

This quirk is related to a trick used to help Parkinson's patients who "freeze" and are unable to take another step. If you lay an item at their feet, and tell them to step over it, they "unfreeze" and can take that step, and then another, and another. The brain sees the item as a threshhold to another place, and the frame of reference re-sets.

To help me remember what I was going to do/get/fix when I go into the other room, I carry something with me, or mumble it under my breath, hold my hand as if I were writing something, some mnemonic device to remember.

What was I worrying about? I forget.