Periods to date when Date Dimension is sorted in desc order

I have been requested to sort the date dimension in descending order. Which I have done, however the some of the date calculations are no longer working because of this.

How would I rewrite this to work with the dimension in descending order?

Sum(
{NULL: [Date].[Calendar Year].CurrentMember}
,[Measures].[Transaction Days]
)

I have tried using periodstodate with order, but I can't seem to get it to work.