When someone spends endless hours at the office and can't put down their laptop on vacation, we might joke that he or she 'works like a crazy person.' But, generally speaking, we don't mean it literally.

Maybe we should.

That's the suggestion of new research from an international team of scientists out of the University of Bergen in Norway, the UK's Nottingham Trent University and Yale. The massive study examined data on 16,426 working adults, turning up troubling links between workaholism and mental illness. Here are the headline findings:

  • 32.7 percent of workaholics met the criteria for ADHD (compared to 12.7 percent in the general population).
  • 25.6 percent met the criteria for OCD (compared to 8.7 percent).
  • 33.8 percent met the criteria for anxiety (compared to 11.9 percent).
  • 8.9 percent met the criteria for depression (compared to 2.6 percent)

What's going on here? Is overwork driving people to mental breakdowns, or are underlying mental health issues pushing people to put in excessively long hours? That remains to be seen, according to Cecilie Schou Andreassen, the study's first author.

"Taking work to the extreme may be a sign of deeper psychological or emotional issues," she commented. "Whether this reflects overlapping genetic vulnerabilities, disorders leading to workaholism or, conversely, workaholism causing such disorders, remain uncertain."

Still, the authors speculate that ADHD symptoms could make getting things done take longer, driving people to work longer hours. Or that the praise that comes from hard work could assuage the stress of those already prone to anxiety. At this stage this all remains guesswork though.

Are you a workaholic?

The results may be preliminary but they should give those who wear their crazy schedules as a badge of honor pause. Other research has already shown that workaholism is completely uncorrelated with actual professional performance -- in short, your constant busyness isn't at all an indicator that you're good at your job -- and, unsurprisingly, that workaholics experience many more negative emotions than more balanced professionals.

Add the fact that workaholism is so tightly tied to mental health problems to this list of research-backed concerns with overwork, and those with over-full schedules should really take a minute to consider what they're getting (or not getting) out of their constant work.

If a moment of reflection has you worried that you might have slipped over the line dividing passionate from compulsive, here's a scientifically-validated checklist of symptoms of workaholism to help you determine if you really have a problem.

What do you make of this latest research?