Scientists have known for some time now that levels of neurotransmitters change during a Migraine attack. Serotonin is the neurotransmitter that’s been most discussed in relation to Migraine. Now a small study using positron emission tomography (PET) scanning has shown that levels of the neurotransmitter dopamine also fluctuate during a Migraine attack. Dopamine is sometimes referred to as the “feel good” neurotransmitter because it helps regulate emotions, motivation, and sensory perception.
“To evaluate in vivo (in the living body) the
dynamics of endogenous (naturally produced by the human body) dopamine (DA)
neurotransmission during migraine ictus (during the attack) with allodynia.”1
• Study participants included eight patients with episodic Migraine and eight healthy control patients without Migraine.
• Study participants were examined using PET scan after injecting with [11C] raclopride, a chemical that binds to dopamine receptors, allowing changes in dopamine levels to be observed by PET scan.
o The uptake measure of [11C]raclopride would increase when there was a reduction in endogenous dopamine release.
o The uptake measure of [11C]raclopride would decrease when there was an increase in endogenous dopamine release.
• Each study participant was scanned twice:
o once during a spontaneous migraine, followed by a sustained thermal pain threshold (STPT) challenge on the trigeminal region, eliciting an allodynia experience
o once during interictal phase (between Migraine attacks)
• Dopamine levels in the episodic Migraine patients were stable between Migraine attacks and similar to the control patients.
• During a Migraine attack, dopamine levels dropped significantly.
*“Our findings demonstrate that there is a reduction and fluctuation in uptake of [11C] raclopride during the headache attack and ictal allodynia, which indicates an imbalance in ictal endogenous DA (dopamine) release in Migraineurs. Moreover, the longer the history and recurrence of Migraine attacks, the lower the ictal endogenous DA release.”*1
Study author comments:
Study co-author Kenneth Casey, M.D., University of Michigan professor emeritus of neurology, commented:
*“Dopamine is one of the main neurotransmitters controlling sensory sensitivity. Therefore, a drop in dopamine could produce increased sensory sensitivity so that normally painless or imperceptible sensory signals from skin, muscle and blood vessels could become painful (allodynia)."*3
Study author Alexandre F. DaSilva, D.D.S., D.Med.Sc., assistant professor at the University of Michigan School of Dentistry and Center for Human Growth and Development, pointed out that the decrease in dopamine levels could partially explain the isolation and social withdrawal that Migraine patients experience during Migraine attacks:
*“This dopamine reduction and fluctuation during the migraine attack is your brain telling you that something is not going well internally, and that you need time to heal by forcing you to slow down, go to a dark room and avoid any kind of stimulation.”*2
Comments and implications for patients:
Given the previously known involvement of the neurotransmitters serotonin and norepinephrine in Migraine, dopamine involvement comes as no surprise. With so few participants in this study, we do need larger studies to replicate the results of this one.
Once this data is replicated in larger studies, it could have significant implications for the acute treatment of Migraine. Medications targeting dopamine could certainly help with many Migraine symptoms, including the need to isolate and the allodynia so common during Migraine attacks.