Cluster headache in relation to different age groups.

Cluster headache (CH) has always been considered a type of primary headache affecting predominantly male subjects in early and medium adulthood. However, recent studies carried out in large case series of patients with CH show that not infrequently it may set in also after age 50; by contrast, onset before adolescence is very rare. Additionally, when onset occurs before age 14 or from the sixth decade of life onward, male predominance decreases to the point that in chronic forms CH predominantly affects the female sex. This particular pattern of the gender ratio in relation to onset in different age groups suggests that hormonal factors may actually play a role in the genesis of CH. In particular, future studies should be aimed at investigating the possible protective role of estrogen.