Causes and Risk Factors of Migraine

In migraine with aura, a person experiences visual, sensory, or speech-language symptoms for several minutes up to an hour, usually followed by a headache. Visual symptoms may include flashes of light or temporary vision loss. Sensory symptoms can include numbness and tingling. And speech-language symptoms include difficulty speaking.

“We have the genetic map of specific types of migraine that are very rare, such as hemiplegic migraine, but for common migraine that most people experience, we don’t have a specific gene that’s been identified,” says Spears.

“If you look at children, boys and girls have about the same rate of migraine, but that changes at puberty, with women jumping to a 3 to 1 ratio. The estrogen hormones, specifically, play a pretty significant role in the expression of migraine,” says Spears.

It’s very common for women to get migraine around their menstrual period, according to Nada Hindiyeh, MD, a headache specialist and researcher at Stanford Health Care in Palo Alto, California. “There are several different types of migraine, and there is a subset of migraine that is related to the menstrual cycle.”

“We believe the reason many women get migraine around their menstrual cycle is because of the drop in estrogen that happens right as the cycle starts. That’s a big trigger for migraine,” says Dr. Hindiyeh.

Neurotransmitters are chemicals that carry signals from one neuron, or nerve cell, to another and from neurons to muscle cells. The messages communicated by neurotransmitters control a variety of functions in the body, some of which play a role in anxiety and depression.

There’s evidence to suggest that the neurotransmitters serotonin, which affects functions such as mood, sleep, and hunger, and dopamine, which affects things like motivation and learning, play a role in migraine as well.

The investigators found that when people with migraine are between attacks, their dopamine levels were stable and normal, but during the attack, the levels fell significantly.

While the underlying cause of most types of migraine — or why one person has migraine and another doesn’t — remains unknown, the various triggers for a migraine attack are better understood. Those include the following:

• Changes in hormone levels, particularly in women
• Allergies
• Environmental conditions, which include changes in weather, stress levels, and food intake, as well as odors and lack of sleep
• Certain medications, including nitroglycerin and phosphodiesterase inhibitors, which are used for sexual dysfunction and include Viagra (sildenafil) and Cialis (tadalafil)
• Dehydration, even mild dehydration
• Excessive caffeine consumption or reduced caffeine consumption

Environmental Triggers of Migraine

“The migraine brain is a brain that likes what we call homeostasis; it does not like a lot of change. When there is change in weather, light, noise, even nutrition — those types of situations will tend to trigger migraine attacks,” says Spears.

• Weather changes, including changes in humidity, temperature, or barometric pressure
• Extreme cold, extreme humidity, or a very dry, dusty atmosphere
• Bright lights, flickering lights, and glare
• Fumes and vapors, including tobacco smoke and carbon monoxide
• Intense odors
• Motion sickness from travel in a car, train, or boat
• Changes in routine that affect stress level, eating, or sleeping
• Physical overexertion

“We know that it’s fairly common to have headache after head trauma,” says Spears. If you have a genetic predisposition for migraine, you have a greater chance of that post-traumatic headache presenting as a migraine-type headache, he adds.

“But there are cases of people who never had headaches, have no family history of headaches, and after head trauma they end up with persistent, severe, migrainelike headaches going forward. They usually don’t have them every day, but they are more prone to them after head trauma,” says Spears.

Episodic migraine is defined as less than 15 headache days per month, while chronic migraine is 15 or more days per month of headache with migrainous features, says Spears. “There is a risk of progressing from episodic migraine to chronic migraine that’s in a range of 1.5 percent to 3 percent per year,” he says.

• Acute medication overuse, meaning three or more days per week of using acute medications to treat headache
• Depression
• Increasing headache day frequency

Increasing headache and acute medication overuse can go together, says Spears. “For example, if you have someone who has two headaches a month, and they notice that increases to more like one headache a week, then two headaches a week, and then they start to treat those headaches with acute medication, which leads to more headache,” he says.

This can turn into a vicious cycle of increased headache days leading to increased treatment days, says Spears. “As you treat more, your risk to progressing to chronic migraine goes up.”

Nonmodifiable Risk Factors for Migraine and Migraine Attacks

• Age and Gender Migraine is more prevalent in women between age 20 and 45.
• Low Socioeconomic Status Research published in Cephalalgia found that women with lower socioeconomic status had increased risk of migraine and increased risk of more frequent migraine attack.
• Head Injury The majority of people who have a concussion have a headache with migraine features afterward, according the American Migraine Foundation.

Modifiable Risk Factors for Migraine Attacks

Spears suggests these ways to reduce the risk of migraine attack:

• Lose excess weight or prevent the development of obesity. According to the American Migraine Foundation, obesity is associated with episodic migraine progressing to chronic migraine.
• Limit caffeine intake.
• Monitor headache frequency and use of acute medication.

“The thinking is that if you go past two [migraine] days a week, you really need to seek medical care for your headache to get it investigated and potentially get onto a treatment plan to keep the frequency down,” says Spears.