Just notice crown thinning

Recently noticed thinning above the crown; is this a sign of MPB? If so, what would the logical steps be to prevent any further thinning?

Crown thinning is often the first sign of genetic balding; however, your does not appear severe enough to worry at this time. You can see a hair doctor and have trichoscopy performed to find out if there is significant miniaturization present, and if there is, then treatment might be appropriate.