You could always lie. I know it's kinda frowned upon, but you wouldn't feel better telling them how isolated you've been anyway. You could tell them you've been taking a few classes, hanging out with your friends or helping your family, working, and that you plan to further your education..that's how I go about it. It's pretty generic and they probably won't ask too much about it, aside from what classes you take and what work you're looking for.
I would save the isolation thing for close future friends
Orrr if you're not really comfortable lying, maybe you could just say that the last few years haven't been so good, but you're working on it. That's good too. Maybe I should erase the part about lying..
I always lie and am very selective with who I tell the truth to. I'd prefer not to tell people who I know will judge me and offer nothing helpful besides make me feel like I'm just lazy, when its far from the case.
If people are curious about what you've been up to keep it to the recent stuff without the big picture. I think only your family or friends who already know you would be nosier than that. Or shake it off with something noncommittal.