Considering that people make anime for all different age ranges, I don't think I can give just one answer to a question like this.
Damn right ! Personnaly, I would say anime like GITS, Witch Hunter Robin, or Texhnolyze are exclusively aiming for an adult audience ... but if you're still a number-one fan of Sakura or Pokemon when turning 30, i'd say it is more ... just unusual.
Same for Amv, they are some for adults, some childish, but most of them are appropriate for all. So i think it's not a matter of age ...