The study was the work of researchers from the University of Michigan at Ann Arbor, and is published online before print in the 28 September issue of PNAS, Proceedings of the National Academy of Sciences.
The Great Depression years from 1930 to 1933 hit the US economy hard: it was the most important economic downturn the country experienced in the 20th century.
For the study the authors examined economic growth and historical life expectancy and death rates for the period 1920 to 1940 and looked for links between annual changes in health indicators and annual changes in economic activity.
The results showed that:
- Population health did not go down, in fact it generally improved during the Great Depression.
- Rates of death (mortality) went down for nearly all age groups.
- Life expectancy went up from 57.1 in 1929 to 63.3 years in 1932.
- Life expectancy went up by several years in males, females, whites and non-whites.
- For most age groups, rates of death tended to peak during years of strong economic expansion (eg 1923, 1926, 1929, and 1936 to 1937).
- In contrast, periods of recession (1921, 1930-1933, and 1938) coincided with declines in rates of death and increases in life expectancy.
- There was only one exception: death rates due to suicide (2 per cent of all deaths) went up during the Great Depression.
- Correlation and regression methods confirmed that economic expansion appeared to have a significant negative effect on health gains.
"The evolution of population health during the years 1920-1940 confirms the counterintuitive hypothesis that, as in other historical periods and market economies, population health tends to evolve better during recessions than in expansions."
First author Tapia Granados, who is a researcher at the U-M Institute for Social Research (ISR) said:
"The finding is strong and counterintuitive."
"Most people assume that periods of high unemployment are harmful to health," he added.
For the study, Granados and co-author Ana V. Diez Roux, a researcher with the U-M School of Public Health, analyzed age-specific mortality rates and rates due to six causes of death that accounted for two thirds of deaths in the 1930s: cardiovascular and renal diseases, cancer, influenza and pneumonia, tuberculosis, motor vehicle traffic injuries, and suicide.
Although the study did not investigate why population health tends to improve during recessions but not expansions, in a separate press statement Granados and Diex Roux suggested some possible reasons:
"Working conditions are very different during expansions and recessions," said Granados.
"During expansions, firms are very busy, and they typically demand a lot of effort from employees, who are required to work a lot of overtime, and to work at a fast pace. This can create stress, which is associated with more drinking and smoking," he explained.
"Also, new workers may be hired who are inexperienced, so injuries are likely to be more common. And people who are working a lot may also sleep less which is known to have implications for health. Other health-related behaviors such as diet may also change for the worse during expansions," added Granados.
In contrast, during recessions, people slow down because there is less work to do, and there is more time for sleep, and because people have less money, they cut back on alcohol and tobacco.
Also, during economic expansion atmospheric pollution rises, and there are well-documented short term effects of this on deaths due to cardiovascular and respiratory problems.
Other reasons why economic expansion may damage health is the possible increase in social isolation and decrease in social support that occur when people spend more time at work.
The authors noted that their study did not examine what happens at the level of the individual: they were looking at population effects, thus highlighting the curious effect that while becoming unemployed may have adverse health problems for a given person, at the level of the population, the result appears to be beneficial.
Granados said that while social science is not physics, some patterns from the past may help us predict the future with some confidence.
"Historical experience tells us that no particular deterioration of mortality is to be expected as a consequence of a recession beyond an increase in suicides which, although clearly important, is of small magnitude compared to the reduced number of fatalities from other causes," said Granados.
He said he hoped the study highlights why it is important to make sure suicide prevention services, often the victim of budget cuts, continue to get financial support during economic downturns.
Other studies have shown that the link between population health and economic cycles may be weakening, at least in the US and in Japan, where sudden death from overwork, "karoshi", a phenomenon seen among salaried Japanese workers, dramatically illustrates the dangers of life during economic boom times.
"Life and death during the Great Depression."
José A. Tapia Granados and Ana V. Diez Roux
PNAS Published online before print September 28, 2009.
Additional source: U-M News Service.