Sounds more like absent mindedness to me than memory problems. I have spent a little time pondering both memory issues and intelligence in general regarding damage that I may have caused myself from the use of narcotics and the like as a youth.
The part that always holds me up is that it is hard or impossible to compare ones memory or mental abilities with that of anyone else. It is like trying to imagine what colors look like to another eyeball, you will never really know. There are some things to gauge it with like an IQ test but even that falls short of really knowing.
I doubt it is possible to really improve memory but it is possible to improve the level of organization with which life is approached and that can have tremendous pay off.