I think that has more to do with the extended time frame than the actual ability of family and medical providers to see changes in a patient cognition and abilities.
You need to live separated for one year to have it approved for one thing. And if you have children under guardianship you are required to attend family counseling or such.
I assume that what is refereed to in the upper comment is the waiting period and other requirements.
Personally I did not know this was the case with altzheimer even though I am Norwegian.
That often happens rapidly, and in many cases putting the Alzheimer's patient in full-time care is the only option -- even with a caring, involved spouse.
I watched my grandfather go from a slightly forgetful goof to confused, violent, and impossible to manage in <3 years. My grandmother, not doing so well herself, struggled to keep up but after a couple years putting grandpa in a facility was the only real tenable option.
There are several things in this discussion that make not much sense to me (a non-Norwegian):
* How would a divorce court refer to a (confidential) medical diagnosis? In some countries, at least, even a criminal court cannot easily access such things.
* Why would the law refer to a diagnosis of a particular disease (when the patient might still be healthy) rather than refer to actual cognitive impairment?
* What's the hurry? Can't you get a divorce fairly quickly just by moving out and filling in some forms?
* One of the major legal implications of divorce is that you don't automatically inherit or get insurance pay-outs. Not the most obvious thing to want when your spouse has a terminal illness, though in some cases you know there's no money involved. Even if you're named in the will there may be bad tax implications if you're not married to the person you're inheriting from.
* Someone mentioned children, but divorce doesn't have to relate directly to children: courts have to deal with the children of unmarried couples, and they have to deal with the children of couples that are separated but still married, so I'd expect a court to worry about the relationships and the welfare of the children and not to care very much whether the parents/guardians are officially married or not.
I would guess that these are all areas of law in which there are a lot of differences between jurisdictions.
I think you are making the assumption that the unhappy and trapped spouse is going to provide loving care. The Alzheimer patient may be better off with other family or in state care than being dependent on somebody who may be hostile to them.
Marriage is a social contract. Some of the benefits (lower income taxes, preferential inheritance, etc) are in recognition that you are taking on some of the responsibilities that would otherwise fall to society.
What you are responsible for and what benefits you enjoy from being married is very much a product of that culture. In my case, if my wife is ill, I do have to provide for her (Fun fact: in Japan you require your spouse's written permission to get a divorce except in certain circumstances). However, it would not surprise me that some other cultures (perhaps Norway) have different responsibilities. The world is large and "marriage" means different things to different people.
Edit: Pointing out flaws/possible exploits in a system is not the same thing as endorsing their use.
(Not that you can't necessarily see cognitive decline externally earlier than a diagnosis, just that it seems like it'd be hard to make a clinical argument about persistent decline versus several poor nights of sleep, for example.)