Can’t wait for the next economic boom to lift all boats—including yours—to greater financial heights? Be careful what you wish for—a good economy can kill, according to a new study by a team of researchers from the Netherlands.

“In developed countries, mortality rates increase during upward cycles in the economy, and decrease during downward cycles,” wrote Herbert J. A. Rolden, a researcher at the Leyden Academy on Vitality and Ageing. The academy is a research institute affiliated with Leiden University and its medical center and is supported, in part, by health-related private companies and non-profits in the Netherlands.

To support their claim, Rolden and his colleagues analyzed cyclical changes in the economy and mortality rates in 19 developed countries, including the United States, the United Kingdom, France and Japan. To fully capture these changes over an extended time period, they collected annual data on business cycles and mortality rates between 1950 and 2008.

Overall, they found that for every 1% increase in gross domestic product (GDP), the death rate for men 70 to 74 years of age increased by about a third of a percentage point (0.36%). The increase was just as large for men 40 to 44 years old (0.38%).

The effect was similar for women, though smaller. The mortality rate for women aged 70 to 74 increased by 0.18% for every 1% increase in gross domestic product and 0.15% among middle-aged women.

They found that people are living longer in the United States and other developed countries.  That means these changes due to the business cycle examined in this study represent relatively small short-term positive and negative shifts from this long-term upward trend.

Earlier studies have tried to explain the counter-intuitive connection between a growing economy and increasing death rate. Most linked it to employment-related changes in lifestyle or behavior. For example, one academic study bearing the evocative title “Good times make you sick” reported that during times of lower unemployment more people have more money to spend—and too many of them apparently spend it on things like fattening foods and cigarettes. As a consequence, smoking rates and obesity increase during economic expansions and, he suggests, so does the mortality rate.

But Rolden noted that bad behavior related to economic factors doesn’t explain why, in good times, mortality rates increase by virtually the same amount among retirement-age adults and those in the middle of their working lives. Besides, most lifestyle changes take years to impact an individual’s health.

So what does explain the link between rising mortality rates during good economic times among adults of all ages?  “The mechanisms underlying the association remain largely unknown,” Rolden and his colleagues wrote.

Like any good mystery, the story these researchers tell has lots of intriguing suspects. They include family members with less time to spend with elderly relatives, increases in air pollution that are known to occur during economic expansions or some X-factor not yet discovered by social scientists.

“So far, the most plausible explanations have been labour-related, but these cannot explain the similar associations we found among older people. Higher levels of air pollution and lower levels of informal care and social support during good economic times could be major contributors to the association, but the evidence on the existence of such dynamics is scant,” they concluded.

However, the researchers also acknowledge that some researchers interpret these data differently. For example, it may actually be that higher mortality rates are driving the upswings in the economic cycles. They write, “If mortality rates of the non-working population increase relative to those of the working population, average figures of labour productivity per capita will increase, raising per capita figures of GDP.”

About the researchers: Rolden specializes on the economics of elderly care. He is a PhD student at the Leyden Academy on Vitality and Aging in Leiden, the Netherlands. The study was co-authored by two Leiden University faculty members, Wilbert B. van den Hout, a health economist, and Rudi G. J. Westendorp, a professor of medicine. David van Bodegom, a physician and health researcher who is currently a graduate student at the academy, was also part of the research team.

Rich Morin  is a former senior editor focusing on social and demographic trends at Pew Research Center.