Isn't it neurotic? Don't you think?

Kendler, Kuhn, Prescott, 2004

This was a very powerful (experientially and statistically) analysis of the role of neuroticism, gender, and stressful events in predicting depressive episodes. I was impressed, frankly, that such analyses have been undertaken at all, and I couldn’t help but wonder what other goodies could be plumbed from the amazing data set (the Mid-Atlantic Twin Registry) that was used. I was also curious about the construct the authors used for “stressful life events.” It seems that their criteria (lasting more than 10-14 days, self-reported, recent relative to the interview date) are neither the most conservative nor the most exploratory of the options that could have been used. I guess that, given the size of the sample, one could argue for the normality of the distribution of adverse life events, leaving this middling choice to be at least representative enough to capture a real phenomenon – but still! What about acute life events NOT captured in the time window? What about more persistent life events? What about the possibility of cyclical or random emergence of depressive episodes and the possibility of those with more primarily neurochemically-induced depression (I now know better than to make a distinction between neurochemically- and non-neurochemically-based, though)? These are the types of questions one might expect to see (or at least see discussed) in an analysis such as this (especially given the advantages of having a large sample of MZ twins), but they were nowhere to be found.

Even more perplexing was the lack of any meaningful discussion of the implication of the findings. The authors speak about the implications as they relate to the modification of a model depression of etiology (an important area of inquiry in its own right), but they say nothing about the implications for individuals who might be at risk for such disorders, and they make no effort to speculate as to why their unexpected findings might have occurs. Specifically, why are females (regardless of rates of neuroticism) so much more likely to have a major depressive episode following a “minor” stressful life event? Does the model of “minor” life events not map appropriately onto the stress-management systems of differing genders? Do women have defense mechanisms against depression that don’t “kick in” until higher levels of distress are experienced? What, if anything, are the implications for targeted treatments for women at risk for depression (e.g. with high neuroticism)? The lack of (apparent) interest in addressing these sorts of “real world” implications for findings seems to be the downside of doing research with an n of 7517.