Hadar Swersky says that loneliness is also a huge reason depression is common among seniors. Social contact decreases as people age, frequently due to lack of retirement, mobility, and other reasons leading to higher rates of senior social isolation. Studies also show that loneliness is a vast risk factor for depression, heightening the sense of unhappiness and worthlessness. Thus, it is important to look out for these symptoms and ease them ahead of time for yourself or your dear one.