As an eldercare advisor, I speak with concerned family members everyday. From my experiences with these families, there are warning signs that I listen for that I ask the families to address immediately:
Med Mismanagement: If you have suspicion of medication mismanagement, please take it seriously. Medication mismanagement can result in confusion, depression, dehydration, and falls that can lead to hospitalization. It is easy to become confused with the amount and frequency of the medication which leads to forgetting dosages or doubling up on them.
Isolation/Withdrawing: If your loved one is starting to isolate themselves or withdraw from doing things that they love, it is important to notice and address this. There could be a variety of reasons for this from beginning dementia to depression to fear. One family couldn't understand why mom no longer wanted to go to her monthly luncheon with her friends and realized eventually that mom could no longer bathe safely and was concerned that her hygiene would be noticed. Her pride did not allow her to address this with family.
Eating/Meal Concerns: Does your loved one only eat high sugar content foods? Do you visit and find the same food in the refridgerator as the week before? Lack of proper nutrition can lead to confusion, diabetes concerns, lower immunity and dehydration.
Forgetfulness: There can be many causes of forgetfulness or short term memory loss. Seeing a doctor should be done to rule out any issues related to dementia or medication related concerns.
As a child or spouse of someone with these issues, it can be very difficult to address these concerns with your loved one. But I deal with so many people who are in the hospital or are in crisis that saw many warning signs and didn't want to address them at the time.
Ask your family doctor if you are concerned. Hire home care or explore assisted living. Educate yourself about what is available to assist your family in your area. No one can tell you what is best for your family....you will collectively decide that. But arming yourself with the information needed to make that decision is critical. You will feel much better about any decision that you make if you feel that you have explored the options available.