The Progressive Era. During the period known as the Progressive Era (1890s to about 1920) the U.S. government became increasingly activist in both domestic and foreign policy.
One possible link between brain freeze and other headaches is local changes in brain blood flow. If further research confirms all these types of headaches are caused by blood flow changes, new drugs that block widening of the blood vessels - called vasodilation - could improve treatment for sufferers.
The brain freeze will usually pass on its own within 30-60 seconds. Sometimes the shock of the brain freeze makes it seem worse than it really is, but if you expect it and know that it'll come and go, it doesn't have to be a traumatizing experience.