We have two main approaches toward making sense of the behavior of our fellow humans. One approach relies on a first-person subjective perspective and provides reasons
for behavior. As humans, we are capable of intuiting the reasons for others’ behavior through the process of empathy. Using the terminology adopted by Jaspers1
(p. 301) such reasons lead to understanding
. If a close friend became depressed after a traumatic romantic break-up, we might feel: ‘Oh, of course. He was really in love with her.’ We feel that we understand the origin of his depression.
The second way we comprehend human behavior is by causes
—that is, objective third-person scientific facts that are established by systematic observation and quantification. For example, studies have consistently found that patients with depression have a threefold increased risk of depression in their relatives.2
On this basis, we conclude that a positive family history is a contributing cause of major depression (MD). Using Jasper’s terminology, causes lead to explanation
The question that we address in this paper is the relationship between reasons and causes for developing MD. Because understanding how reasons for MD might act as causes is so central to this paper, and might seem at first glance odd or abstract, we give two clinical vignettes to ‘ground’ this concept in clinical common sense.
Assume you are evaluating two patients each of whom presents with a depressive syndrome. Like most good clinicians, you carry in your head a list of empirically validated causes of such a presentation including medical disorders (for example, endocrine abnormalities), early environmental exposures (for example, childhood sexual abuse), genetic risk factors and potential psychological vulnerabilities (for example, high levels of neuroticism). Assume that in the early stages of your history taking, patient A tells you that his business recently burnt down with great financial loss and his beloved only child was diagnosed with a potentially fatal childhood cancer. Patient B, whom you know to be a reliable informant, tells you that everything has been going well in her social and family life, and at work, and her depression emerged ‘out of the blue.’ In the terms used in this article, patient A has good reasons to be depressed while patient B does not. That is, at the level of common sense psychology, the depressive episodes of patients A and B appear to be, respectively, quite understandable and rather un-understandable.
Many clinicians would, on hearing the story of patient A, conclude: ‘Yes, it makes sense to me why he became depressed.’ They would assume that the reasons given by this patient for his depression were causes that both ‘made sense’ to them as humans and constituted a causal explanation that could be used to guide further evaluation and treatment. Given that they felt they had a good explanation for the episode, they would not spend much further effort pursuing, by history or laboratory tests, other potential causes for this depressive episode. Furthermore, sensing that the depression arose understandably from external stressors, many clinicians might be willing to take a ‘watch and wait’ approach rather than developing a more aggressive treatment plan. By contrast, the workup would be more thorough for patient B because without good reasons for being depressed there ought to be some good causes to be found. Without a good psychological explanation for the emergence of the depression, an active pharmacological treatment approach would more likely be adopted.
Goals of this paper
The question that we address in this paper is the relationship between reasons and causes for developing MD. More specifically, we evaluate two hypotheses about this relationship: the reasons are causes and the trap of meaning hypotheses. The above clinical vignettes illustrate the implications of the ‘common-sense’ hypothesis that reasons are causes. An unambiguous prediction of this hypothesis is that, on average, individuals with many reasons for developing MD will have fewer causes. That is, in a group of depressed patients, we will observe a robust inverse relationship between the degree of understandability of their MD (which reflects the number and plausibility of their reasons for developing depression) and the presence of objective causes for MD (for example, personality, genetic loading and exposure to early environmental adversities).
By contrast, our alternative trap of meaning
hypothesis assumes little to no relationship between reasons and causes. That is, while the reasons patients give us for the emergence of their disorders may help us to empathize with them and improve our emotional relatedness, they actually tell us little about the objective causes of their illness. A recent article about the trap of meaning3
forcefully argued that physicians do a disservice to their patients by assuming that understandable symptoms do not need further diagnostic evaluation or treatment. Specifically, the trap of meaning hypothesis predicts that in a group of depressed patients, little or no relationship would be found between the degree of understandability of their depressive episode and the presence of objective causes for MD as determined by their personality, their genetic loading and their exposure to early environmental adversities.
In this article, we evaluate the ‘reasons-as-causes’ versus ‘trap of meaning’ hypotheses for MD by examining detailed interviews with 630 twins who experienced an episode of MD in the last year, from a longitudinally assessed population-based registry. These interviews contained rich contextual information that permitted us to rate, with high reliability, the level of understandability (LOU) of their episodes. Furthermore, we have for this cohort detailed information about a range of empirically validated genetic and environmental indices of risk for MD. How would these causes for being at high risk for MD relate to the reasons for their current episode as reflected in our measures of understandability?