Americans die younger in conservative states than in those governed by liberals, a new study has found.

The authors wrote: “Simulations indicate that changing all policy domains in all states to a fully liberal orientation might have saved 171,030 lives in 2019, while changing them to a fully conservative orientation might have cost 217,635 lives.”

The study was published on Plos One, “an inclusive journal community working together to advance science for the benefit of society, now and in the future”.

The authors are from Syracuse University in New York, Harvard in Massachusetts, Virginia Commonwealth University, the University of Washington, the University of Texas at Austin and the University of Western Ontario, in Canada.

They wrote: “Results show that the policy domains were associated with working-age mortality.”

Bucking the trend, the study found that “more conservative marijuana policies” were associated with lower mortality rates.

But it also found that “more liberal policies on the environment, gun safety, labour, economic taxes and tobacco taxes in a state were associated with lower mortality in that state”.

They added: “Especially strong associations were observed between certain domains and specific causes of death: between the gun safety domain and suicide mortality among men, between the labour domain and alcohol-induced mortality, and between both the economic tax and tobacco tax domains and CVD [cardiovascular] mortality.”

According to the National Council of State Legislatures, as of June this year Republicans controlled 61% of state legislatures and Democrats 35%. In terms of whole state governments, Republicans controlled 46% and Democrats 12%, with 12 states divided.

The study authors also noted that American life expectancy as a whole is lower than in most high-income countries, “fall[ing] between … Cuba and Albania”.

They wrote: “The rise in working-age mortality rates in the US in recent decades largely reflects stalled declines in cardiovascular disease mortality alongside rising mortality from alcohol-induced causes, suicide and drug poisoning; and it has been especially severe in some US states. Building on recent work, this study examined whether US state policy contexts may be a central explanation.”

With federal and state midterm elections less than two weeks away, increased social spending in legislation passed by Democrats in Congress and the Biden administration has become a key issue in voters’ minds.

Joe Biden and other senior Democrats have sought to emphasise the success and necessity of such measures. But Republicans, who have presented such measures as irresponsible and contributing to inflation, are poised to retake the House and perhaps the Senate.

The study authors wrote: “One study found that US life expectancy could increase by nearly four years if the country matched the average level of social policy generosity offered in 17 other high-income countries.

“More recent research has turned attention to policies and politics at the US state level, given the federalist structure of the US political system and the large size and geographical spread of the population. This new work suggests that changes in state policies and politics may have played a contributory role in producing the troubling US mortality trends.”