Sunday, October 26, 2014

Is the incidence of depression higher where people are experiencing more negative emotion and suffering?

It would be difficult to be interested in human flourishing without having some interest in understanding the differences in incidence of “suffering”, negative emotion, and depression in different parts of the world.

I have written a few posts about negative emotion recently, but it is now a few years since I looked explicitly for a relationship between “suffering” and depression at an international level. The last time I looked, I couldn’t see any relationship. I concluded that “the data … suggest there is no simple relationship”.

There is now some new data available, so I have taken another look. But I don’t want you to get too excited, because you might end up feeling disappointed.

A data set on depressive disorders in 2010 has been compiled by Alize Ferrari and others as part of the Global Burden of Disease Study. The researchers collected data on the depressive disorders from published articles and pooled the data using a statistical technique (Bayesian meta-regression). The data used below relates to major depressive disorder (MDD) which is also known as clinical depression. It involves at least one major depressive episode in which the affected individual experiences a depressed mood almost all day, every day for at least 2 weeks.

The negative emotion data is sourced from the Gallup World Poll. Respondents were asked if they experienced worry, anger, sadness or depression yesterday. The data used is based on country averages of yes/no answers (yes = 1).

The data on suffering is from the new Gallup-Healthways Global Well-being index. The index covers 5 dimensions of well-being: purpose (liking what you do and learning or doing something interesting); social (having supportive relationships); financial (having enough money to do what you want and not being worried about money); community (liking where you live and having pride in your community) and physical (feeling active and productive, and in good health). People are classed as suffering in a particular element if their well-being in that element is low and inconsistent.

For the purpose of this exercise I have estimated the percentage suffering in each country as the average of the percentages suffering in each dimension.

After the three data sets were combined I had data for 114 countries. At the country level, there is a modest degree of correlation between the three variables:
Struggling and MDD:                          0.24
Struggling and negative emotion:        0.20
Negative emotion and MDD:              0.06 .

The graph presented below provides a basis to compare averages for the relevant variables in 10 regions of the world.

All three indicators tell an unambiguous story of misery in the Middle East and North Africa. Suffering seems somewhat higher in Sub-Saharan Africa, but the incidence of negative emotion is apparently lower in that part of the world than in the Middle East and North Africa.

Central and Eastern Europe seems to have a fairly high incidence of all three indicators of misery. The incidence of depression and suffering is similarly high in the former Soviet countries, but the incidence of negative emotion is similarly lower.

East Asia stands out as having a relatively low incidence of negative emotion and depression, but a higher incidence of suffering than Latin America. According to the Gallup-Healthways data, the incidence of suffering in Latin America is not much greater than in Europe.

It is possible to speculate on reasons why the three indicators tell different stories in several regions of the world. Cultural factors probably explain the relatively low incidence of negative emotion in East Asia and Sub-Saharan Africa. Cultural factors might also explain why the incidence of suffering has been assessed to be relatively low in Latin America. (As discussed in an earlier post, cultural factors might also explain why the Gallup-Healthways index shows a high percentage of the population in Latin America to be thriving). There may also be potential for the estimates of depression to be biased by such factors as differences in availability of trained mental health professionals.

That leaves me concluding that caution is required in comparing suffering, negative emotion and depression in different parts of the world. I know that is a fairly lame conclusion, but I did warn you not to get too excited.

No comments: