If I were going to hike in Alaska I would carry pepper spray.
And likely it would be my first response.

Some if's. How would one us it if:

If one were attacked in a tent?

Strong wind in the face?

If it goes off accidentally while driving the car?

If it goes out of date after 2 years?

If the temp dips low and the stuff won't work?

If the temps get hot and it explodes?
http://www.survivalreviews.com/index.php/articles/selfdefense/130-really-bad-deal

When a bear is already mauling a friend?

--

One study alone is not enough. And both the park service and the
national forests in Alaska say bring more than one kind of
protection.