Depression is a normal mental condition characterised by a sense of inadequacy, despondency, lack of vitality, pessimism and sadness. But depression can be a serious illness with the potential to become a world epidemic. Major depression is a condition that can cause an inability to function or even suicide but can remain undiagnosed.
Collective depression can be related to national trauma, that is, a shock felt by a very high percentage of a population. Other causes of collective trauma are political assassinations, episodes of genocide, acts of war, economic depressions, technological disasters, natural disasters, and uncontrolled pandemics. All of these events can trigger collective depression, either in a direct way, or by a more insidious process of gradual accretion.
As depression may be passed between individuals by contagion, treatment involves leadership, group development, social learning, collective insight, political changes, and even just the passing of time, though the healing process may never be complete. The function of leadership in alleviating collective depression is to correctly diagnose the causes of the depression, and then to demonstrate that situational factors can be changed. But bad leadership can also be the cause of collective depression through what has been called toxicity. As with individual depression, collective depression can have a positive or functional side, leading to growth of insight in a process that can later be recognised as heroic. The incremental modification of collective depression will inevitably lead to the gradual lifting of individual depressions by the mechanism of 'reverse contagion'.