That work load should have no effect on risk of depression sounds downright whack. In none of the summaries of the three linked articles do I see that part of the claim documented by their data.
Below are the "results" sections from the summaries of the two non-saliva articles among the 3 referenced in the posted "article".
From "A two-year follow-up study of risk of depression according to work-unit measures of psychological demands and decision latitude."
RESULTS:
The OR for depression according to psychological demands was 1.07 [95% confidence interval (95% CI) 0.42-2.49] for every unit of change on a 5-point scale. The corresponding OR for decision latitude was 1.85 (95% CI 0.55-6.26). No interactive effects of psychological demands and decision latitude were observed.
CONCLUSION:
These findings suggest that low decision latitude may predict depression, but confidence intervals are wide and findings are also compatible with no increased risk.
From "Work-unit measures of organisational justice and risk of depression--a 2-year cohort study."
RESULTS:
Working in a work unit with low procedural justice (adjusted ORs of 2.50, 95% CI 1.06 to 5.88) and low relational justice (3.14, 95% CI 1.37 to 7.19) predicted onset of depression.
CONCLUSIONS:
Our results indicate that a work environment characterised by low levels of justice is a risk factor for depression.
"That work load should have no effect on risk of depression sounds downright whack."
Then again, two of the summaries you quote actually suggest that things have a lot more to do with office politics and work environment.
Think of it this way: if you've an infinitely long todo list, but no pressure whatsoever ("wake me up as you complete the tasks"), it's just an insurmountable amount of work that you'll grow used to never completing and you'll do as much as you can and be satisfied with yourself.
Now, toss a boss into the equation -- one that tells you to get it all done by yesterday. Or put another way, one that essentially goes: "let me load your backpack with 50kg before I order you to swimm across this river". That can screw you up rather quickly. Especially if that boss's priorities change daily or hourly.
I don't mind the infinitely long to-do list, but I get stressed out by having constantly changing priorities that force me to drop a project before it's done and work on a new one. Long-term strategic projects (which tend to be the most interesting to work on) can get dropped and resumed several times before they get completed, and each time that happens it seems more painful than the last time.
Below are the "results" sections from the summaries of the two non-saliva articles among the 3 referenced in the posted "article".
From "A two-year follow-up study of risk of depression according to work-unit measures of psychological demands and decision latitude."
(http://www.ncbi.nlm.nih.gov/pubmed/22885721):
RESULTS: The OR for depression according to psychological demands was 1.07 [95% confidence interval (95% CI) 0.42-2.49] for every unit of change on a 5-point scale. The corresponding OR for decision latitude was 1.85 (95% CI 0.55-6.26). No interactive effects of psychological demands and decision latitude were observed.
CONCLUSION: These findings suggest that low decision latitude may predict depression, but confidence intervals are wide and findings are also compatible with no increased risk.
From "Work-unit measures of organisational justice and risk of depression--a 2-year cohort study."
(http://www.ncbi.nlm.nih.gov/pubmed/23476045):
RESULTS: Working in a work unit with low procedural justice (adjusted ORs of 2.50, 95% CI 1.06 to 5.88) and low relational justice (3.14, 95% CI 1.37 to 7.19) predicted onset of depression.
CONCLUSIONS: Our results indicate that a work environment characterised by low levels of justice is a risk factor for depression.