A study published this month in the Journal of Applied Psychology examined a sample of 6,769 German adults -- 3,733 men and 3,036 women -- who took the same personality test twice in a four-year window. During the experiment, 251 subjects were unemployed for less than a year; 210 faced joblessness for one to four years.

The authors focused on five traits: conscientiousness, neuroticism, agreeableness, extraversion and openness. Dispositions of perpetually job-hunting people transformed considerably -- and dismally -- compared with their steadily working counterparts.

“Unemployment,” researchers wrote, “has one of the strongest impacts on well-being ... often lasting beyond the period of unemployment and being comparable with that of becoming disabled.”

The findings in Germany have domestic implications. One characteristic of America’s slow economic recovery is the extraordinary number of people who have fallen into the ranks of the long-term unemployed, those unable to find jobs for 27 weeks or more. An estimated 3.4 million fit this description, by the Economic Policy Institute’s measure.

That figure doesn’t tell the whole story, of course: Some people take temporary gigs, only to tumble back into unemployment. Some just stop looking.

To exacerbate matters, our ability to find work may decline if self-esteem shrinks. Depression is higher among long-unemployed Americans, according to a recent Gallup poll: About one in five reported having depression. That’s nearly double the rate of those unemployed for five weeks or less.

The mental health impacts of unemployment can be devastating. A CDC study found suicide rates rise and fall with the economy.

"Public policy therefore has a key role to play in preventing adverse personality change in society through both lower unemployment rates and offering greater support for the unemployed," Cco-author Christopher Boyce, research fellow at the University of Stirling in Scotland, told the American Association for the Advancement of Science.

Jobless men in the APA study became more agreeable at first, the initial test showed, perhaps enjoying the novelty of free time. But in the second test, two years later, they displayed crankier traits than the men who held jobs.

Out-of-work women hit that threshold of bitterness faster: Agreeableness diminished with each year of joblessness.

"In early unemployment stages, there may be incentives for individuals to behave agreeably in an effort to secure another job or placate those around them," the researchers wrote, "but in later years when the situation becomes endemic, such incentives may weaken."

More fairly obvious findings: Jobless men showed a healthy amount of openness in the first year of unemployment, but levels dipped the longer they searched for work. Women seemed far less open in the second and third years of unemployment.

Both sexes presented more neurotic traits after long bouts of unemployment. That’s likely because income isn’t the only loss suffered, researchers noted. Losing your job can feel like losing your sense of community.