It's not unusual to see symptoms of depression post illness in many types of serious illnesses. For example, it's common in people who have had bypass surgery. Some studies think it may be physiological in origin, others think it is psychological. To me, it makes sense that it is either or both.

Being run down physically certainly makes it hard to feel good, and trying to adjust to your body not being able to do what you think it should is also hard. For people concentrating on just fighting to keep their health, post treatment time might be the time they can really stop to think about what it all means.

Whatever, the cause no one should have to live with it. For some it just passes. But other folks may need therapy and/or medication. And caregivers need to watch for the symptoms in themselves too. It's so easy to be focusing on your loved one that all of a sudden the symptoms creep up on you!!!