Truthstare

When you cast this spell, you enchant your eyes to detect the presence of certain magics. For the duration, you can examine a willing creature within 5 feet to discern the presence of mind-altering magic.

This only works for existing effects, telling you the nature of the alteration, but not the specifics. For example, for a creature whose memories had been altered (as by modify memory), you would be able to tell that their memories had been altered, but not which ones or how long ago.