Recently, a colleague who has done research on life events and bipolar disorder published a blog posting about some of my ideas regarding how mood illnesses can help leadership. My view was that many great historical leaders had depression or bipolar illness, not merely by chance, but because there are features of these conditions that enhance the ability to lead.
One critique made is that people with mood illnesses are prone to becoming depressed or manic based on stressful life events. There is an immense scientific literature on this topic which is well-known. People who have a severe depressive episode are more likely to have experienced a stressful life event within the past year (like divorce, moving, job loss, death of loved one, medical illness), compared to people without mood illnesses.
How then can it be that great leaders could have mood illnesses? Wouldn’t they have even more depression or mental instability under the many stresses of political and military crises?
Now this is an interesting assumption. Like so many assumptions, it is simple, plausible, and wrong (to paraphrase HL Mencken).
It is wrong psychologically and historically.
Psychologically: The above research does not work in both directions – If people have depression, they are more likely to have had recent stressful life events than people without depression. But this does not mean that if people have stressful life events, they will experience depression. Obviously, most people have many stressful life events without ever getting depressed. People lose their jobs all the time; everyone dies; everyone gets sick: but in most of those cases, no one gets depressed. Why do some people get depressed, and others not, after stressful life events? Why do most of the population experience stressful life events without ever getting depressed? Only at most 10% of the adult population ever experiences even a single depressive episode in a lifetime, but everyone experiences those stressful life events at some point in life.
The reason why some people get depressed after stressful life events, and others don’t, is that some people have the disease of depression, and others don’t. Diseases of depression and bipolar illness reflect the susceptibility to getting depressed or manic, not the mere fact of being depressed or manic. Most of the time, such persons are not depressed or manic. Under the trigger of stressors, and sometimes spontaneously in a cyclic way, they can have episodes of depression or mania, before they go back to their normal mood. Mood illness is about susceptibility to mood episodes, not the presence of mood episodes.
So it is a mistake to conclude from the life events research that mood illnesses mean that you always get depressed or manic with stressful life events. Most people never have mood episodes with stressful life events, and even most people with mood illnesses do not have mood episodes much of the time with stressful life events. They sometimes do, more so than the general population.
Let's put it another way: Suppose someone with bipolar disorder has a stressful life event. Are they 100 percent likely to have a depressive or manic episode afterward? 50 percent? 20 percent? When we say they are more prone than the general population, we are saying that they are more likely than 0 percent to have a mood episode. (By definition, if you have a mood episode, then you have a mood disorder, according to DSM convention; so the comparison to the general population is to those who never have any mood episodes). When one seeks the absolute frequency of mood episodes after a stressful life event, the percentage is definitely not 100 percent and it isn't even a majority likelihood, i.e., more than 50 percent. The actual percentage is quite low: one study which controlled for genetic risk found that there is about 6-14 percent risk of having a depressive episode after a stressful life event in a person with major depressive disorder.
Psychologically, then, there is increased susceptibility to mood episodes with stressful life events, but even so, this is not a simple cause-effect relationship: often life events happen without mood episodes.
The claim that this relationship between life events and mood episodes contradicts the idea of benefits to mood illnesses for leadership is like saying that the sun is hot, and tables are solid. These are two true statements that are unrelated to each other. Many of the great historical leaders I studied experienced depressive or manic episodes after stressful life events, and yet, in between mood episodes, they functioned well, perhaps even better than others, I think, partly because of their past experiences of depression or mania.
Further, in these leaders, their “normal” mood is often a little high: mild hypomanic symptoms as part of one’s temperament called “hyperthymia”. There are no stressful life events that trigger temperament or personality: one’s personality is one’s personality. Hyperthymic temperament has been shown, based on studies I document, to enhance resilience to stress – not only a decreased likelihood to having depression with a stressful life event, but even a decreased likelihood to having depression with an extremely traumatic life event. About 90 percent of persons exposed to severe trauma don’t develop PTSD; 10 percent do. In the resilient 90 percent, hyperthymic temperament – meaning mild manic symptoms – is a predictor of not developing a PTSD reaction.
So, yes, stressful life events are more likely to trigger mood episodes in persons with mood illnesses, but this does not contradict the fact that there are benefits to mood illnesses, especially with the hyperthymic temperament, which protects against mood episodes even with severe traumatic events.
Historically, Churchill and Lincoln got severely depressed before their terms in national office, with regular life stresses, but they did not become depressed at all while two major wars raged on around them.
Life stress and mood illness is not straightforwardly causal, and both the scientific and historical facts argue against the claim that mood illnesses somehow weaken a person as a leader. The reverse is often the case.