Depression, is just not being sad or feeling discouraged, it is an illness. It may just ‘look and sound’ like felling ‘blues’ , but in fact depression last much longer and have greater impact on one’s life. Depression, can simply happen to anyone, at any stage. It could possible cause people to live in state of feeling hopeless, or in such severe sadness state that one may just lost interest in their daily activities.
Especially during time of transition, depression are particularly vulnerable in elderly, of which could be few time higher at risk. Apart from this, hormones could also be part of the cause. This is why depression is such common during premenstrual and postpartum period.