"What medicines are you taking? How do they make you feel?"
This question asks for two answers. The first speaks to your parent's relationship to caregivers and whether he or she is being treated like an equal party in his or her own care management.
The second is a way to ferret out possible mismanagement or medication abuse.
Not all elder abuse is done out of malice. It may be that caretakers are not coordinating and sharing information with each other, or that a caregiver is ignorant or neglectful. This is especially true when it comes to medications.
Older people are often on several medications, and they all have possible adverse side effects and interactions. You can act as an advocate for your parent. Does your father seem sleepy and out of it whenever you visit? Is your mother complaining of pain?
If you have power of attorney for your parent, you can request to see medical charts and records. Look for changed dosages or new medications and speak to the prescribing doctor.