Smell is Taste
The sense of smell is the ability to discern chemicals in the air. Taste is the ability to discern chemicals in our food. Our food sheds some of these chemicals into the air which is why we're able to smell it. While taste and smell are different senses which use different organs to doing the work, they are tightly coupled. Think of how you re unable to properly taste even your favorite foods if you're fighting a head cold. The inability to smell dramatically impacts the ability to taste.
One of the change that is commonly noted with Alzheimer's patients is a decreased ability to smell. We've read about the peanut butter test which uses peanut butter held mere inches from a person's nose to determine if they should be evaluated for Alzheimer's. We've read about Alzheimer's patients no longer being able to smell lavender, leather or citrus scents. In Alzheimer's the brain is being actively damaged and a lost of smell is a symptom of this.
We also have read of Lyn's changing tastes and an apparent forgetting of her food preferences. This is also a common symptom of Alzheimer's. The sense of taste is also dramatically impacted by the damage done to the brain. However, the two senses are so interdependent that we shouldn't consider their decline independently of each other.
We don't know how much of the loss of taste or the change in food preferences is a result of the direct damage to the neurons involved in that sense or how much is a result of the damage done to the sense of smell. I suppose it doesn't really matter. However, for me at least, it points to the fact that the change in food preferences is a result of the damage done to the sense of taste. It is not a mystery after all.