One of the main reasons people may react so strongly to stressful events lies in the fact that negative emotions are stored as memories in the unconscious mind. These implicit or embedded memories are centered in an almond shaped area of the brain known as the amygdala. The amygdala is sometimes thought of as the fear center of the brain and conditions such as anxiety, autism, depression, post-traumatic stress disorder, and phobias are all suspected of being linked to abnormal functioning of the amygdala.
The fact that we can retrieve negative memories so rapidly is part of the problem. What originally evolved as a mechanism to help remind and protect us against genuine threats seems to be over-sensitive in some people and this results in an over-reaction to situations perceived as threatening.
If malign memories are stored during childhood they can continue to affect us as adults, even though as adults we may not be conscious of them. Each time stressful experiences are encountered there is an amplification of negative memories, which can dictate our responses.
This in part explains why people who suffer with anxiety find the situation so frustrating. At one level they are entirely aware of the fact that their emotional and behavioral reactions are out of proportion to their situation, yet at another they feel incapable of more adaptive responses. This is the problem of implicit memories, they can affect our moods and interact with our thoughts so that they are irrational and we have no way of knowing why.
Some of the so-called talking therapies specifically try to work with the patient in order to access and redevelop implicit memories. This way the underlying causes of anxiety and depression can be uncovered and coping strategies developed to make them more tolerable.