Here’s a true modern puzzle for you: why is the rate of mental health problems, including depression, anxiety, and obesity, increasing in the US, Australia, urban China, and most Western countries?
Which mental health problems again? Depression, anxiety, and obesity are the big growth areas. And, yes, I view obesity as a mental health problem, ie the result of a lack of willpower.
Let me give you the quick stylised facts on these arising from the literature.
An authoritative paper on depression in 1989 said on the increase since WWII that
“Several recent, large epidemiologic and family studies suggest important temporal changes in the rates of major depression: an increase in the rates in the cohorts born after World War II; a decrease in the age of onset with an increase in the late teenaged and early adult years; an increase between 1960 and 1975 in the rates of depression for all ages; a persistent gender effect, with the risk of depression consistently two to three times higher among women than men across all adult ages; a persistent family effect, with the risk about two to three times higher in first-degree relatives as compared with controls; and the suggestion of a narrowing of the differential risk to men and women due to a greater increase in risk of depression among young men. These trends, drawn from studies using comparable methods and modern diagnostic criteria, are evident in the United States, Sweden, Germany, Canada, and New Zealand, but not in comparable studies conducted in Korea and Puerto Rico and of Mexican Americans living in the United States. These cohort changes cannot be fully attributed to artifacts of reporting, recall, mortality, or labeling and have implications for understanding the etiology of depression and for clinical practice.”
A recent 2011 paper on the US summarises the available evidence thus:
“Almost all of the available evidence suggests a sharp rise in anxiety, depression, and mental health issues among Western youth between the early 20th century and the early 1990s. Between the early 1990s and the present, more serious problems such as suicide and depression have receded in some data sets, whereas feeling overwhelmed and reporting psychosomatic complaints have continued to increase. Other indicators, such as anxiety, have remained at historically high levels but not continued to increase. This mixed pattern of results may be rooted in the increasing use of antidepressants and therapy and the improvement in some cultural indicators. However, the incidence of youth mental health problems remains unacceptably high.
Just a few generations ago, depression and suicide were considered afflictions of middle age. However, throughout the 1960s, 1970s, and 1980s, the average age of onset for depression moved downward (Klerman & Weissman, 1989), and the suicide rate for young people (aged 15–24, per 100,000 population) skyrocketed from 5.2 in 1960 to 13.3 in 1995 (U.S. Bureau of the Census, 2011). Numerous studies reported sharp increases in the lifetime prevalence of depression, including among adolescents and young adults (e.g., Lewinsohn, Rohde, Seeley, & Fischer, 1993). Only 1%–2% of Americans born before 1915 experienced a major depressive episode during their lifetimes, even though they lived through the Great Depression and two world wars. By the 1990s, the lifetime rate of major depression was 10 times higher—between 15% and 20%. Some studies put the figure closer to 50%. (Kessler et al., 1994; Wickramaratne, Weissman, Leaf, & Holford, 1989).”
So for depression in the US, we are talking about up to 50% of the population who will experience a bout of it, a ten-fold increase from the generation born in WWI. For anxiety, studies say that some 30-50% of the current generations in the US and Europe will be affected by some anxiety disorder or another in their life, again orders of magnitude higher than two generations ago.
For obesity, the same can be said: from being a problem that afflicted a couple of percent in 1900, we are fast approaching a situation where the majority of the population in the US is obese. This is already true for the 50 to 60 years of age population and rates in other western countries are on the rise too, showing no sign of a slow-down.
The role of medicine is interesting here: the effects of anxiety and depression seem to be kept manageable by medicines preventing the sufferers from committing suicide or becoming psychotic. The effects of obesity are similarly countered by medicines, through blood thinners, bypass operations, and the like. So whilst rates of mental health problems are at an all-time historical high, medicine is successful at reducing the impact on people’s lives.
Here is the puzzle: what on earth is going on here? On any objective measure, life is better now for the vast majority of the population than ever before. People are richer, live longer, run fewer risks, are surrounded by less violence and large shocks, and essentially have less to fear and be depressed about. Indeed, people are as happy now as ever, reflecting the fact that these are good times. Why then the increase in mental health problems in societies like the US, Australia and most of Europe?
Take just the obesity puzzle: One can basically out of hand reject the excuses most individuals give for their problems as being the reason. The rate of increase rules out any reasonable role for genetics. The fact that the poor suffer more from obesity, whilst it is cheaper to eat less and whilst food has always been cheap for the rich, rules out any obvious effect of the lower price of food or the availability of fast-food. The sustained increase over a long time rules out any story depending on some major current crisis. Like it or loath it, but it is clear that one must look at ‘cultural factors’ to have a hope of understanding what is going on.
A big hint comes from cross-national differences amongst rich countries, where things like wealth and food affordability dont differ much. As you can see here, the Anglo-Saxon countries, and then particularly the US, stands out. Whilst a third of adults in the US are now obese (with about 25% of Australian adults), only 4% of Koreans and Japanese are such, and in the more egalitarian Northern European countries (Sweden, Norway, Holland) rates are below 10%. The same holds for Italy and France, though rates in those countries too are quite a bit up from what they were 50 years ago. So your one major clue is that there are major unexplained differences over countries. Similar things hold for the other mental health problems.
Which cultural factors though and what underlies changes in these cultural factors? This is a wide-open and currently empty field in health economics. Your suggestions are thus greatly appreciated in the comment boxes!