Seventy-year-old Franco has begun to experience a reduced activity level, loss of close relationships, and a loss of independence. These are all associated with

depression

Explanation:

Depression is the most frequent mental illness in the elderly. It is characterized by a decrease in serotonin, which is a neurotransmitter that regulates emotions of well-being and sleep. In this mood disorder feelings of sadness, anger or frustration interfere with daily life for weeks or longer.