Causes and Risk Factors of Migraine

The causes of migraines are primarily neurologic, but also involve genetic factors. Symptoms, including premonitory symptoms, aura, headache, and postdrome phase, involve dysfunction in several parts of the brain, pain pathways, and brain chemicals. There are also many exacerbating factors that are associated with the triggering of migraines.

Common Causes

Migraines are thought to have a variety of possibly causes, including:

Genetics

It is very difficult to pinpoint the genetic basis of migraines because it is likely a complex interaction of many factors. However, migraines are probably inherited. In fact, there's a higher rate of both twins having migraine headaches in identical twins, with the same genetic makeup, versus fraternal twins, with different genetic makeup.

There are a few abnormalities in the neural pathways of the brain that have been identified in certain groups and individuals who get migraines that are linked to genetics. However, genes do not act alone—additional environmental factors make individuals more prone to migraines. Researchers are still looking for the exact genetic causes so effective treatments can be created.

Brain Structure

Some studies have shown that some people with migraines have altered blood flow to areas of the brain that involve migraine symptoms. Structural changes in the brain have also been identified.

Estrogen

Women may be prone to migraines since estrogen has several important actions in the central nervous system. Usually, menstrual migraines occur within a window of two days before the onset of period bleeding to three days after the onset of bleeding. Estrogen may affect some chemical mediators, such as magnesium, which may alter the excitatory and inhibitory neural pathways in the brain.

Cortical spreading depression

It is believed the pain that follows a migraine with aura is due to something called cortical spreading depression. This is when parts of the brain become depressed, causing inflammatory changes in the pain-sensitive parts of the brain that generate the headache of migraine.

Sensitization

Sensitization is the process by which neurons, the cells in the brain, become increasingly responsive to stimulation. This is likely the cause for many of the clinical symptoms of a migraine, which includes worsening of pain with certain motion, sensitivity to painful stimuli, throbbing sensation, and even increased sensitivity to painful things that may not normally cause pain.

Cardiovascular

The evidence is currently conflicting, but associations have been made between migraines and a congenital heart defect called a patent foramen ovale. A patent foramen ovale, also known as a right-to-left cardiac shunt, is when the hole between the right and left atrium doesn't close at birth. Other congenital heart defects, such as an atrial septal defect, have been linked to migraines. The mechanism as to why this might occur is not completely understood. It's possible that an underlying genetic basis ties the two conditions together. Other theories involve the change in direction of blood flow with these heart defects.

Migraine Triggers

In a study published in 2007, 1,200 patients were evaluated to determine the relationship between triggers and migraines; 75.9 percent of them reported triggers. Forty percent infrequently had triggers, 26.7 percent frequently had triggers, and 8.8 percent very frequently had triggers. The leading triggers were:

• Stress, reported by 80% of participants
• Hormone changes in women, reported by 65%
• Not eating, reported by 57%
• Weather, reported by 53%
• Sleep disturbance, reported by 50%
• Odors, such as perfume, reported by 44%
• Neck pain, reported by 38%
• Lights, reported by 38%
• Alcohol, reported by 38%
• Smoke, reported by 36%
• Sleeping late, reported by 32%
• Heat, reported by 30%
• Food, reported by 27%
• Exercise, reported by 22%
• Sexual activity, reported by 5%

Poor sleep quality and obesity have both been associated with increased migraine frequency and severity. Sleep apnea, jaw clenching, or teeth grinding may also trigger migraines. These things may exist together, as those who are obese may have sleeping disorders, such as sleep apnea.

Migraine headaches can sometimes get worse by constant movement, physical exertion, and rapid head motion. Certain psychiatric conditions may also impact migraine frequency. Caffeine can be a trigger as well.