An important first step to guard against truss movement is adequate ventilation. Remember, a minimum of 1 square foot for every 300 square feet of attic space. Attics can be a great place to develop condensation which will be picked up by the wooden truss members. It's important to keep the moist air vented to the outside.
Do a tight job of the ceiling vapor barrier. As we strive for air-tight houses, a good job of keeping the envelope tight is a must. If you don't then any little pin-hole in the ceiling vapor barrier will transfer moisture from the inside of the house into the attic.
The image to the left is an example of a bracket used to secure the trusses to the partitions without the danger of the bottom chord lifting the wall up when uplift occurs. The slot in the bracket lets the nail slide up with the truss while still holding the wall in place.
This will stop the trusses from lifting the whole wall and creating a space between the bottom of the wall and floor.