Hi Hayfa,
Some food for thought for sure! I've been contemplating this for a long time. External negative circumstances and environmental influences could affect some in certain ways and others differently. Personality, character, idiosyncrasies, one's coping mechanisms and levels of resilience as well as external supports family history, age, gender, worldview and faith/belief systems may assist or hinder mental health in relation to a positive or negative reaction to an environmental factor such as war, migration, loss and grief, disasters, terminal illness etc. In traumatic situations it is normal to grieve and feel sad and a way of our mind trying to deal with the enormity of the event and normalize it so we can continue living. However, I think also that as many have experienced, mental illness, including depression and anxiety at times may not be associated to any specific event or traumatic experience. It could simply be a hormonal or physical/neurological condition. Some neurotransmitters in the brain could be out of whack and in need of adjustment. Certain preservatives and pesticides as well as certain illnesses also may cause depression and/or anxiety and change in moods. And so does a lot of medication used to treat certain conditions. Recent studies indicate that there is direct correlation between our gut and our brain. If our immune system, which is solely in our gut, is compromised, then our mood will also be affected. Food and mood are also directly linked. So I believe that sometimes mental illness could be unrelated to external circumstances and/or experiences of trauma and could strike to otherwise healthy, happy and well-adjusted individuals.