Risk Factors:

Cluster headaches are rare, affecting less than 1% of the population.

Age and Gender

Cluster headaches can affect all ages, from children to the elderly, but are most common from young adulthood through middle age. Men are 2 - 3 times more likely to have cluster headaches than women, with the peak age of onset during their 40s. In women, age of onset tends to be in their 60s.

Unlike with migraines, fluctuations in estrogen and other female hormones do not appear to influence the onset of attacks in women.

Lifestyle Factors

Lifestyle factors, including smoking, alcohol abuse, and stress (in particular stressful work situations), appear to play a very strong role in cluster headaches. Smoking or alcohol use can trigger attacks. (However, quitting smoking generally does not have an affect on the disease course.) Alcohol, most commonly red wine, may trigger an attack.

Family History and Genetic Factors

Cluster headaches tend to run in families, suggesting a genetic component may be involved in some cases.

History of Migraine

About half of people with cluster headache have a personal or family history of migraine. Studies have reported that about 15% of patients have both kinds of headache.

Head Injury

Head injury with brain concussion appears to increase the risk of cluster headaches, although a causal relationship has not been proven.

Sleep Apnea and Other Sleep Disorders

Cluster headaches tend to occur during specific sleep stages and have been associated with several sleep disorders, including narcolepsy, insomnia, and sleep apnea.

Sleep apnea, a disorder in which a person stops breathing during the night, perhaps hundreds of times, is of particular interest. In some people, apneas may trigger cluster headache during the first few hours of sleep, making patients susceptible to follow-up attacks during the following midday to afternoon periods. Treating patients who have both disorders with a device called CPAP, which opens the airways, may help improve both conditions. [For more information, see In-Depth Report #65: Sleep apnea.]

Cluster Headache Triggers

The following conditions and substances might trigger cluster attacks:

• Alcohol and cigarette smoking
• High altitudes (trekking, air travel)
• Bright light (including sunlight)
• Exertion
• Heat (hot weather, hot baths)
• Foods high in nitrites (such as bacon and preserved meats)
• Certain medications (including those that cause blood vessel dilation, such as nitroglycerin, and various blood pressure medications)
• Cocaine

Triggers usually have an effect only during active cluster cycles. When the disorder is in remission, such triggers rarely set off the headaches.