Neurotic people aren't only making themselves miserable; they cost society billions of dollars in health care spending and lost productivity, according to new research from the Netherlands.

We thought that economic costs would be a good way to assess the overall impact of neuroticism, Dr. Pim Cuijpers of VU University Medical Center in Amsterdam, one of the study's authors, told Reuters Health in an email. We were surprised that the impact was this large.

While the least neurotic individuals cost society less than $3,000 per year, he and his colleagues found, the most neurotic people cost more than $22,000 annually.

Neuroticism -- a proclivity toward worry, anxiety and emotional ups and downs -- is considered to be a personality trait with genetic roots, and is strongly associated with several types of mental illness, including depression, anxiety and schizophrenia.

While research has looked into the economic costs of individual mental disorders, most studies of neuroticism have focused on just one disorder or aspect of mental health, Cuijpers and colleagues point out in the Archives of General Psychiatry.

To better understand the overall impact of neuroticism, in and of itself, on society, the researchers looked at about 5,500 adults drawn from the general population. They looked at their medical costs and the amount of days they were absent from work to come up with an annual figure (in dollars). They assessed neurotic traits using a 14-item scale crafted from a personality inventory questionnaire used widely in the Netherlands.

The researchers found that the average costs for people who scored in the top 5 percent based on neuroticism were $12,362 over and above the average for the population. Excess costs for people in the top 10 percent were $8,243, while costs for the 25 percent who scored the highest on neuroticism were $5,572.

The increased costs associated with neuroticism were considerably higher than those for associated mental health problems, for example mood and anxiety disorders, substance use disorders, and somatic disorders (meaning psychologically related physical problems), the researchers note.

For example, common mental disorders cost an extra $600 million per million inhabitants, they estimate, compared to nearly $1.4 billion for neuroticism. This is largely because there are so many more people with some degree of neuroticism than there are people with mental illness, Cuijpers noted.

The rest of the excess costs associated with neuroticism could be related to mental disorders that the researchers did not look at, such as personality disorders and sleep problems, Cuijpers told Reuters Health. The second possibility is that neuroticism has a unique contribution to the costs. It is not possible with our data to say which of the two is correct.

While the fact that neuroticism is a relatively stable personality trait means it's difficult to change, the researcher added, we can, however, work on early treatments of problems associated with neuroticism, such as depression and anxiety disorders. We can also try to prevent such problems in people scoring high on neuroticism.

The findings show, he added, that personality affects not only the individual, but society as well. If this is realized as a common understanding, there are many levels at which these problems could be reduced, Cuijpers said. For example, employers can develop a good mental health climate, and mental health services can be included as basic needs in health care in general.