As we age the facial skeleton changes. One of the changes that occurs is that we loose bone and one of the areas this happens is the forehead.
When we loose bone from the forehead it can create a contour change and this is seen as a break in the continuity of the forehead.
Woman should have a smooth contour but in men it is more accepted for a contour change (this is called a suproribital ridge).
This loss of bone can be corrected with the use of dermal fillers such as Juvederm Volbella. This may also improve horizontal forehead creases.