A 1000 years of memories could drive any one insane, i mean, what is our mental capacity? I'm sure we could keep the body alive and healthy for a long period of

A 1000 years of memories could drive any one insane, i mean, what is our mental capacity? I'm sure we could keep the body alive and healthy for a long period of time, but a 1000 years is probably too much. The brain would have to adapt somehow, we would probably forget most of our experience and only keep the most important memories, our brains were designed for 30-40 year life-spans, nature really didn't intend us to live as long as we live today. We've managed so far by forgetting stuff thats not that important, but how would our memory management work in a longer period?