And this is a particular general population survey as it happens, of, of
twins, but I'll show you lots of data below, of general population surveys.
And I'll be using the term incidence
sometimes, and that brings the cohort concept into
play, that's a prospective study, and sometimes
I'll be using the word prevalence, or association.
And that brings the case control logic
into play, which is the retrospective logic.
Here is a personality trait, called
neutroticism, this is a well studied trait,
and neuroticism is the tendency that an
individual has to react strongly to stress.
So, it means people get anxious or moody
or distressed or upset in the context of stress.
Some people do more, we know this, some people are calm in
the face of stress and some people are all anxious and upset in the face of stress.
So we measure that trait, neuroticism, then we look forward in time.
To people who have more neuroticism, or less neuroticism.
And we consider stressful life events in that context.
So if you look on the left hand chart, that's the males, and you can see
that some of those males, the orange triangles,
and the orange bar, have very high neuroticism.
And they are much more likely to have an episode of depression in the future.
In other words the trade is measured at one point in
time and they have incidents of depression after that point in time.
That's the cohort logic.
And so you can see that the orange bar is
higher than the red and, and blue and green bars.
And that means that neuroticism is related to onset of depression.
But you can also see that it's
interacting with stressful life events.
So, people who have a severe life event and a
life event that's rated as severely upsetting to their life
plans and the meaning of their life, those people have
the most likely possibility of having an episode of depressive disorder.
And so as you move from left to right the stress of the
life event gets from none or minor to severe and their risk for depression
goes up and this is true for males and females.
And one final note about males and females.
Again we see females have slightly higher risk for
depressive disorder at any given level of neuroticism, and at
any given level of stressful life events, the females
are more likely to have an episode of depressive disorder.