Donald Trump waves to supporters in Roanoke, Virginia, on September 24th, 2016. (Photo: Sara D. Davis/Getty Images)

The factors that drove support Donald Trump in the United States and Brexit in the United Kingdom have been well-parsed by this point: racial resentment, the fear of demographic change, economic hardship, the pain of feeling left behind in a globalized economy.

But new research reveals another element that contributed to those anti-establishment votes: neuroticism.

In both nations, "regions high in neuroticism were more likely to vote in the populist direction," reports a research team led by Martin Obschonka, a psychologist at Australia's Queensland University of Technology.

The finding is "consistent with the idea that populist campaigns played on the fears of the voters," the researchers write. After all, they note, "campaigns that draw on fear should be particularly compelling to people already prone to being anxious."

Obschonka and his colleagues examined the intersection of personality and poll results on the county level in the U.S., and the "local authority district" level in England, Wales, and Scotland. (Data was not available for Northern Ireland.)

Personality data was collected using two large Internet surveys—one of which was completed by 3.1 million Americans from 2,082 counties, while the other featured responses from 417,217 Brits.

Using participants' responses to statements measuring various personality traits, the researchers noted each region's average level of neuroticism, as well as the "subfacets" of anxiety and depression. This data was compared with the percentage of voters who supported Trump or Brexit—and, in the U.S., the extent to which Trump gained support over 2012 Republican presidential candidate Mitt Romney.

"Rural areas in the east of England, and the industrialized centers, have higher neurotic traits, and higher Brexit votes," the researchers report. In the U.S., "Trump gains (over Romney's level of support) and higher neurotic traits overlap. The 'rust belt' shows a concentration of both neuroticism and Trump gains."

People wave Union flags in London, England, on June 24th, 2016. (Photo: Geoff Caddick/AFP/Getty Images)

The researchers then further analyzed the data, taking into account a number of things that could influence voting in a given region, including economic hardship, traditional political attitudes, average levels of education, and "the regions' industrial heritage."

The impact of neuroticism largely persisted after controlling for those factors, "particularly in the U.S," they report in the journal Social Psychological and Personality Science.

"We observed stronger effects of neurotic traits when examining Trump gains (from Romney, compared to the simple share of Brexit and Trump votes," they write. This finding, they add, "underscores our initial assumption" that neurotic people were more receptive to Trump's assertions that the nation was falling apart.

It would be unfair and unhelpful if Trump and Brexit opponents used these findings to dismiss voters on the other side as mentally ill. Neuroticism is not a medical condition, but rather a personality trait. Living in a perpetual state of anxiety isn't fun, and it's easy to see how it would make you more vulnerable to being manipulated by fear-based political campaigns.

Perhaps one way to prevent another Trump is creating a culture in which people who suffer from emotional problems feel free to seek, and are able to receive, the help they need.