I think its possible only if you have been away from your own country for far too long and never get in touch with any of your friends or relatives thru voice or video calls, emails and chat messages. Even so, there will be a bit of words here and there that one can't ever forget.
And yes, it will also depend on age. As one grows old we tend to forget more and more. This morning I forgot again what I have forgotten about. It's silly but it keeps getting frequent.