Can divorce increase your risk for Alzheimer's?

I was just reading an interesting article in the archives of the New York Times about divorce and dementia and Alzheimer’s disease written by Tara Parker Pope back in August 2008. And she makes the argument, based in a Finnish study, that people who had experienced divorce or some other traumatic loss of a spouse and who remained single from middle age on, where six times more likely to develop dementia and Alzheimer’s than people who were married. Those folks who never married were only 2 times as likely as married couples to develop Alzheimer’s in their older years.
So it’s kind of like better to remain single, than get married and have it not work out — and remain single after that — if you want to avoid Alzheimer’s.
I wonder why that is? Maybe it’s some sort of defense mechanism. Reality is too awful, so it’s easier to forget. Maybe subconsciously people start to practice forgetfulness after they lose a spouse through divorce, and if they never find another spouse to replace the one they lost, their practiced forgetfulness is eventually “mastered” and then they really can’t remember at all.  They become demented…
Very sad. The study certainly suggests that divorce is a serious emotional “crisis” and “trauma” that sometimes does not show symptoms till much later in life. I guess the takeaway is, try to avoid divorce if you can. Or don’t get married in the first place if the person you are marrying is not the right person that you will grow old with.