In fact some of the depression in old age are due to the genetic makeup which we inherit from our parents. There are more than 350 million people are suffering from depression in the world and the quantity is increasing as the negativity in all walks of life is increasing. 

Depression is commonly seen among the aged and is equally common in the younger generation. Reasons can be anything from personal loss to unfulfilled desires to serious illness. It can be related to season called SAD (seasonal affective disorder ) or as simple as scoring less marks in exams for students. It happens when one is unable to handle the harsh realities of life. Support from family and friends play a big role in getting over difficult situations. It is a state of mind where one is unable to see anything positive in their life.Chronic depression should be handled delicately and help from professionals should be taken. It is important to remember that those who are going through it whether old or young are highly vulnerable and and need help. Doctors normally prescribe anti-depressants but nothing works if there is no support system.

Yes genetics play a vital role in depression. I know a few people who will plunge themselves in to depression  just for a small reason. And they will be brooding over the situation for days on throwing themselves further and further in to depression. This type mental attitude will lead to several ailments.

Also the symptoms of depression cause an chemical; imbalance in the brain. This can be corrected by doctors by giving medicines. It has to be supported by counselling  for curing completely. However the treatment periods are usually long and costly. But there is no way out. family support to elderly can reduce chances of depression.

There are several ways to curb depression.  contacting doctor is the last thing I do. Depression can be stopped by the Allopathic medicines. But the side effects are more. My  way of handling depression is Pranayama.

The side effects are usually temporary. Please do not say the doctor should be contacted last as the cases of depression can become severe if left unattended. Depressions which can be cured by Pranayama are not actually depressions of the kind being discussed here. Yoga is good for toning the body but it is not a miracle for every wrong the body faces.

I'm doing Pranayama since decades. Neither depression nor negative thought touched me. See this link

http://eyogaguru.com/cure-depression-stress-and-anxiety-by-pranayama/

Everyone cannot be a Baba Ramdev or Rambabu. 

One need not be like me. One can practice Yoga without any trained Guru and reap the rich fruits of health.

Yoga is not the end all to all the problems in life, like all other fields it has its own limitations. An active and fit person may have many other problems other than health and to expect Yoga to cure it is stupidity ! Some of the villagers and peasants who commit suicide here are physically fit but poor, this is enough to cause depression, so how does yoga help them? they need financial assistance more than anything else !