blue spruce die back?

[9shooter]

A friend of mine has several blue spruce trees in his yard that have needles dying on the interior of the tree. On each branch all the needles are dead except the last 6"-12" on each branch. This seems to be spreading from tree to tree.  The top 4-6' of the trees seem ok. I did not see any insect bore holes in the trunks. These trees are about 8" DBH. Any ideas?

[Phorester]

Which State are the trees located? 
Also, at first thought,  the outer needles on conifers are the youngest, they will be the current year's growth.  Interior needles are 1 to 2 years old, and die and drop naturally every year. That's how you get a carpet of needles on the ground underneath conifers.   This needle fall usually occurs in the fall.  But if there has been some sort of stress on the tree, such as drought, too much rain, etc., they will drop earlier in the summer.  This may be what is occuring here.

Generally, if the outer needles are still okay and the buds at the ends of the branches are still alive (soft, and fresh looking, not brown) the tree is okay.