If you lived with someone with MCI, you would soon learn, as I did, that inconsistency is the rule of each day. It depends on the mood or attitude of the person at a particular time, so it is difficult to asses whether the person is being difficult, stubborn, or just unable to be cooperative in his or her thinking.
So you must learn a peaceful response to every episode because to argue or criticize or correct the thinking or action just makes everything worse.
Early on, you learn not to ride with them when they are driving, as it may not be safe. You remember to not respond to their directions in a quiet way so they may not notice that you did not follow through. You hide your strong pain meds so they don't steal them. They may eat unsafe food from the refrigerator so you check the dates and clean out often because lack of taste or smell is an early warning sign of trouble. The hardest part is that you never know if they are being "foggy" in their thinking or if it is just stubborn refusal to cooperate as a fight to maintain their independence. Do not wait to find out. Protect yourself if you wish to outlive a person with MCI. And get control of the money needed to get everyone through the ordeal. It may take years!