scientists aren't sure what causes migraines including migraines without aura. it's thought that at least two brain chemicals -- serotonin and dopamine -- play a role. the theory is something goes awry in the way these chemicals regulate brain function. this causes the brain and the body's immune system to overreact. when that happens a flood of immune response cells flows through the blood vessels to the brain. the brain's blood vessels open wider to accommodate these cells. then even more chemicals are released to help control the vessels' muscles. the vessels open and constrict. a severe sometimes throbbing headache results. factors suspected of causing migraines include genetics and being overweight. substances behaviors and environment may also trigger migraines. it is known that migraines often run in families. they frequently begin in childhood and worsen through adolescence. although more boys than girls have migraines more adult women than adult men have migraines. over time the number of migraines lessens. migraines become rare after age 50.
what causes a migraine without aura?