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.
Eating a large quantity of ice cream is a common cause for a brain freeze. The temporary freezing of nerves behind the hard palate is considered part of the cause of brain freeze. Shrinking blood vessels cause the brief but intense pain of a brain freeze.