The new information relating to a potential cause of migraines has come from positron emission tomography scans of the brain, undertake at the University of Michigan. These scans have shown how dopamine levels fall and fluctuate at different times during a migraine headache. Dopamine is a neurotransmitter released by the brain that plays a number of roles in people; one such connection is linked to reward-associated behavior. Most types of rewards increase the level of dopamine in the brain, and many addictive drugs increase dopamine neuronal activity. The neurotransmitter also helps to regulate sensory perception.
The research was led by Dr. Alex DaSilva from the University of Michigan. The research involved taking different measurements of the brain in eight subjects who suffer with migraines and eight people who do not. With the migraine sufferers, readings were taken during migraine incidences and between incidences.
Migraine is a severe type of headache, typically affecting one half of the head. The headaches are pulsating in nature, lasting from two to 72 hours. Other symptoms may include nausea, vomiting, and sensitivity to light, sound, or smell. There are probably various causes for migraines. One potential trigger region is the sphenopalatine ganglion a nerve bundle located at the back of the nose. A second candidate is microbial: the mouths of migraine sufferers seem to harbor significantly more microbes with the ability to modify nitrates than people who do not get migraine headaches, suggesting a dietary trigger. A third area of research is genetic (38 independent genomic regions are associated with migraine).
The new research found that when migraine patients were between headaches the dopamine levels were as stable and matched those of the healthy patients. However, during a migraine attack the dopamine levels fell significantly. This means a drop in dopamine may produce increased sensory sensitivity, which means that normally painless sensory signals from skin, muscle and blood vessels suddenly become very painful.
The researchers also found that sometimes external factors can make the migraine worse. For example, when a warm pad was applied to the forehead of sufferers’ pain increased. Normally this should not happen, highlighting an aversive reaction to environmental stimulation.
The implication of the research is that I should aid medical researchers in better understanding dopamine-based therapies for migraines. The findings may also help medics to better understand an individual patient’s behavior during an attack.
The research is detailed in the journal Neurology, with the paper titled “Dopamine D2/D3 imbalance during migraine attack and allodynia in vivo.”
Read part 2 of our migraine special
In related research, a different research group has found generalized anxiety disorder is more common among adults who have migraines than those without migraine. This is important because many people with migraines have pain that prevent some daily activities. This is detailed in a companion article published on Digital Journal (“Why do migraines occur? Part 2: Migraines and anxiety.”)