The 2 main causes of depression:

1. Genetics or Background – Those who have a family history of depression, have a sensitive disposition, suffer from anxiety, view the world with pessimism or have a chemical imbalance in the brain are all at risk of developing depression.
2. Environmental Factors that Occur throughout Childhood – This includes how someone has been raised by their parents, as well as how they are influenced by those around them.

Depressions tends to occur when someone experiences an event or events that stimulate their stress levels. It may also occur without these kinds of negative stimuli but such cases are in the minority.

If you suspect that you or someone close to you is suffering from depression, watch for the following symptoms. If you observe at least 5 of these symptoms occurring in conjunction with each other for a period of no less than 14 consecutive days, with the symptoms occurring throughout the day, the person could be suffering from depression:
 

1. Feeling down and fed up (for children and teenagers, this may mean that they get easily frustrated or lose their temper frequently)
2. Feeling bored, losing interest in activities and not gaining any happiness from doing things
3. Insomnia, restless sleep or sleeping through the day
4. Getting tired easily and lacking energy
5. A loss of appetite or overeating
6. Feeling worthless and losing all self-esteem
7. Finding it difficult to concentrate on tasks or feeling hesitant about doing things
8. Speaking slowly, carrying out tasks more slowly than usual or feeling fidgety and being unable to sit still
9. Harboring feelings of self-harm and self-destruction

The main thing given is counseling and psychotherapy, and antidepressants if needed

Balanced nutrition, adequate rest, regular exercise, mindfulness, and optimistic mindset