The study in the article you quoted does not give any definite answer to whether or not brain damage does not cause any symptoms. As it shows in the text quoted from the news article:
The researchers also noted that their findings are preliminary and need to be replicated in a larger study.
Unless you are in a situation where you have repeated head injuries or near explosion site, which is the target for the study, I don't think you have any reasons to suspect having brain damage.
Stress does have some impact on your overall well being but there's no study saying that it can cause real damage to the brain. To be able to be certain that brain can be damaged by stress, there must be a lot of different studies done on large population to determine if stress does cause brain damage before you should consider your risk of having brain damage. Even if it is the case, you still have to have real proof (with by means of having a doctor diagnose you *actually* have brain damage) to be certain that you unluckily damage your brain due to stress. Otherwise, looking at just one study/news does not mean anything. There were so many bogus studies before and the media are notoriously famous for reporting exaggerated/untrue information.
One example of such study done by my aunt, who does not
work in medical field, is below:
Stress is really dangerous. It can cause *real* damages to many of your vital organs, including your kidney, your liver, your stomach, your heart, your colon.
Even she has done the study, she has not suggested that stress damages your brain. Therefore, you should not be worried.
PS: I was not meant to make fun of you. It just happens that my aunt does say something similar so I quoted it here