Dronabinol is a capulated oil form of THC that is prescribed for nausea, vomiting, wasting syndrome, and appetite loss. Would you allow your elderly to take such a drug? If they took it in the past, did it help them at all?
What to prescribe is best left to the medical professionals. I understand that the elderly often react differently to drugs than when they were younger. Caregivers always should be alert for side effects which may indicate the meds are doing more harm than good -- in this case possibly listlessness and paranoia.