I a moment ago found out that my dad forgets stuff- forgetful?

just found out that my dad forgets things or who you are especially when he's exhausted. is this something serious?I a moment ago found out that my dad forgets stuff- forgetful?
Not necessarily serious, but he should see an MD. There may be something vascular or neurological.
all right he could have alzheimers disease. that's when his brain cell start to dissolve all by themselves. see a doctor something like this.
i cant remember people i met for a while if i havent see them in a long time. I be a sign of even relatives, and old friends. But it MIGHT not be serious. I even forget instructions and the resembling, though my dad doesnt belive me...