Increasing Discount rate increases /decrease Interest cost ?

[maxmeomeo]

THe swchezer says : Increasing discount rate will usually reduce Interest cost ( PBO * Discount rate).
Can anyone help explain why? From my understsanding there are 2 effects here:
-Increasing discount rate will increase interest cost (1)
-Increasing discount rate will lower PBO (2)
Normally the (2) effect will be more profound ( for plan that is not mature yet), thus Interest cost is reduced.
Am I getting it right ?
How can we know if the plan is mature or not?

 

[Zanalyst]

Not sure about the maturity part but the way I understood it was:
1) Increasing discount rate will not increase interest cost.
This is because
2) Increasing the discount rate will decrease the PBO.
The service cost is a PV amount and is included in the PBO. The higher the interest rate the lower this PV number is.
Even though you multiply the PBO with a higher discount rate, that PBO is lower than it was pre-interest rate increase.