Migraine and tension-type headache did not show a simple bidirectional linear worsening from headache-free state to definite migraine or vice versa, a new study found. Researchers evaluated the course of headache in a large population from first assessment in 2008 through a second assessment in 2013. Factors associated with persistent migraine and persistent tension-type headache were examined. The researchers found:

• Only 42.9% of definite migraineurs in 2008 received the same diagnosis again, and of the remaining migraineurs, 23.3% were newly diagnosed as definite tension-type headache.
• The 17.7% of patients with definite tension-type headache in 2008 were newly diagnosed as having probable tension-type headache, 14.7% as having definite migraine, 6.4% as having probable migraine, and 28.9% as headache free in 2013.
• Only 32.3% received the definite tension-type headache diagnosis again in 2013.