Interesting, do you have any handy links on that? What's the theory behind it? Is it because of a recession like drag on the economy from the loss of income earners and people never can afford to retire? Or is it because the number of vacant jobs cause employers to offer lucrative salaries to keep people in them instead of retiring?
The closest thing that I can point you to would be this recent article in The Economist:
http://www.economist.com/displaystory.cfm?story_id=14743589
Start reading where it says "The Goldilocks moment". That isn't word for word what I was referring to, but it'll get you started. I didn't want to search for more articles, but they exist.
Basically you have three possible situations that are common.
1) You have a young population where there are significant numbers of children. Think many African countries. There is a huge burden to feed/clothe/shelter the kids that the country needs as many workers as possible. Retirement is rare.
2) You have a old population where there are significant numbers of elderly people. There is a huge burden to keep these people alive. Think Japan and soon the US and parts of Europe. There aren't many workers per elder and everyone who can work, needs to work. As this ratio gets worse, the country cannot sustain the idea of retirement.
3) In between. Most of the population is working. There aren't too many kids nor too many elders. This golden era is ripe for retirement. Plenty of people can take your place and support your retirement.
We are leaving #3 for #2.