The national electorate often is framed in terms of partisan or generational divides. But there’s another important polarization of the electorate to consider: the health divide.

In short, people with chronic illnesses, mental health concerns, and disabilities — not to mention people suffering from the seasonal flu — are less likely to vote. One study estimates that over 3 million voters in the United States did not vote in the 2010 elections due to the so-called “disability gap” in turnout. (One notable exception: Having cancer is associated with an increased likelihood of voting, according to multiple studies.)

The upshot? As one featured paper explains, “if healthy people are more likely to turn out and have systematically different policy preferences than the unhealthy … then electoral results and the policies that are enacted may have a ‘health bias.’ This suggests a feedback cycle linking population health to politics: increasing health disparities may produce increasing inequalities in policy representation, which in turn produces policies that may be detrimental to the unhealthy, which in turn creates even greater health disparities, and so on.”

To get a better sense of the connections between health and voting, this research roundup gathers the latest scholarship on the subject. 

“Influenza and Voter Turnout”
Urbatsch, R. Scandinavian Political Studies, March 2017.

Election season and cold and flu season tend to overlap in the U.S. and many other countries. Researchers exploited this coincidence to determine whether voter turnout in Finland and the U.S. change with varying rates of local influenza prevalence.

Key finding:

• In both the U.S. and Finland, influenza outbreaks were associated with lower voting rates.
• In the U.S., the authors estimate that a state reporting “widespread” influenza rather than “no activity” would have reduced turnout by 4.9 percentage points.
• In places within the U.S. with a higher density of generalist health care providers, there are stronger turnout-dampening effects from influenza – in other words, even fewer people vote.

“The Bodies Politic: Chronic Health Conditions and Voter Turnout in the 2008 Election” 
Gollust, Sarah E.; Rahn, Wendy M. Journal of Health Politics, Policy and Law, December 2015.

Does voter turnout vary by particular chronic illnesses? This study looks at turnout in the 2008 U.S. presidential election among voters with five different chronic conditions – cancer, diabetes, arthritis, heart disease and asthma.

Here’s what they found:

• People with cancer were 2.6 percentage points more likely to vote in the 2008 election than people with any of the four other conditions.
• People with heart disease were 2.4 percentage points less likely to vote.
• Socioeconomic status and race played into these “chronic condition effects.” The authors found that among respondents who had cancer, African Americans and people without a college education were more likely to vote than their white and well-educated peers.
• People with poor self-rated health, no insurance, disabilities, and less emotional support were also less likely to vote than the general population.

“How Different Forms of Health Matter to Political Participation” 
Burden, Barry C.; et al. The Journal of Politics, January 2017.

This study analyzes longitudinal data collected for over 50 years on more than 18,000 Americans. The researchers looked at various health measures, including walking speed, cognitive functioning and scores from a general health index, to determine whether there were associations between these metrics and political participation (as measured by voter turnout and campaign contributions).

Key findings:

• Those who maintained their cognitive functioning (as compared with those who experienced cognitive decline) were more likely to vote.
• Higher general health scores and faster walking speeds (which were used as an indicator of physical health) were also associated with higher rates of voting.
• The health measures studied had weak or no associations with campaign contributions.

“Health and Voting in Young Adulthood”
Ojeda, Christopher; Pacheco, Julianna. British Journal of Political Science, July 2017.

Using a longitudinal dataset that tracks responses from 9,000 youths annually, this study analyzes the impact of physical health, mental health and overall well-being on voter turnout.

Key findings:

• Poor self-rated physical health reduces a young adult’s likelihood of voting in their first election, but not later elections.
• The opposite held for depression—it had little influence on the likelihood a young adult would vote in their first election, but was associated with changes in voting over time.
• “Physical limitations do not have a statistically significant effect on either the initial probability of voting or a citizen’s trajectory in young adulthood.”

“Can You Deliver a Baby and Vote? The Effect of the First Stages of Parenthood on Voter Turnout”
Bhatti, Yosef; et al. Journal of Elections, Public Opinion and Parties, April 2018.

This study looks at voter data from Denmark and Finland to analyze whether new parents were less likely to vote in local elections. It turns out it’s hard to juggle a newborn and civic responsibilities.

Key findings:

• In Denmark, parents generally were good about voting, with turnout around 60 percent over the two years studied. However, turnout dropped sharply among parents to children born close to the election. The results from Finland were similar.
• “Parents with a child born one to seven days before the elections are 19 percentage points (Denmark) and 10 percentage points (Finland) less prone to vote than the base group. For parents with children born 8 to 14 days before the elections were held, the corresponding figures are diminished to six and one percentage points.”
• Childbirth had a larger effect on turnout among women than men.

“Expanding Medicaid, Expanding the Electorate: The Affordable Care Act’s Short-Term Impact on Political Participation” 
Haselswerdt, Jake. Journal of Health Politics, Policy and Law, August 2017.

When more people have health insurance coverage, what happens to voter turnout? This paper uses district-level elections data from 2012 and 2014 U.S. House races to probe this question.

Key findings:

• “Increases in Medicaid enrollment associated with the expansion are related to considerably higher voter turnout.”
• “This effect was likely due to both an increase in turnout for new beneficiaries and a backlash effect among conservative voters opposed to the law and its implementation.”