I know people who have had severe depressive episodes that didn't return once they were over. Usually they made lifestyle changes to lower their stress levels and make sure to eat right, exercise, and practice good "mental hygiene".

I also know a few people whose depression only shows itself when they are having large life stresses and who go on and off medication.

Then there are many whose depression seems to become chronic with only short breaks (if they're lucky) when their mood feels "normal".

I don't know if these are the same brain conditions.

It's nice to know that not everyone who has a major episode of depression ends up dealing with it for the rest of their life, though.