I am the same age as you and I noticed a definite slip about 4 years ago. I got evaluated for it just last month and this is my story.

4 years ago, I started walking into rooms in my home not remembering what I came in there for. Also, I started forgetting that I had just told someone something. This really bothered me because I always prided myself on having a good memory. As the years went on I became more obsessed with checking dates, street numbers, appointment times, and so on.

Fast forward to this year. My long term memory is still good but I'm still dealing with the frustrating short-term crap and I've had to resort to iPhone reminders, constantly writing things down, etc. In May I happened to be in a neurologist's office for an entirely different matter - chronic back pain affecting my right leg in weird ways that didn't resemble sciatica. I mentioned this memory stuff to her and she ordered a MRI of my brain, a neuropsychological examination, and a sleep study. That may sound radical, but my insurance paid for all of it so I figured why not just so I would have peace of mind.

- the brain MRI was perfect
- the neuropsych evaluation was last month. It lasted 3 hours and was performed by a psychologist. It is comprised of various intelligence, cognitive, and motor skills testing. The results showed that I had some weakness in certain isolated recall tasks but that it was not concerning and did not show a chronic degenerative deficit. The psychologist's ultimate opinion was that this memory slide is due to my chronic pain (which didn't make sense to me because the chronic pain didn't kick in until 3 years after I noticed something different), lack of sleep (makes sense), "polypharmacy" and it was suggested that I try to reduce the number of meds I'm on—uh, that's a no-go—and my ongoing depression and anxiety. The only recommendations he made that were helpful to me were to break down larger tasks into smaller ones, and to do monotasking instead of multitasking. The sleep recommendations he offered are things I was doing already, and they're not working.
- sleep study is coming up this Friday evening. I really hope they find something on this test because I am waking up an hour earlier than I am supposed to every single morning covered in sweat with intense heart palpitations. This is really ruining my life and it takes me until noon or 1pm to calm the hell down. I try not to take benzos or beta blockers for these "events" but I can't help it. Deep breathing, mediation, and caffeine cessation have failed.

Anyway, I didn't find the MRI or the neuropsych eval to be a total waste of time. I was glad there weren't any "surprises" going on inside my brain. I just didn't find the suggested solutions to the neuropsych problems to be all that helpful. This may be worth looking into if it's bothering you that much. Good luck.