Currently, doctors have to diagnose chronic migraine (CM) based on clinical symptoms alone. There is no accepted biomarker for the debilitating condition. But new research found there may be one found in calcitonin gene-related peptide (CGRP) levels of women with chronic migraine.
The study, published online August 23 in Neurology, found elevated levels of CGRP, a neurotransmitter that causes vasodilation, in the peripheral blood of women with CM compared with a control group of women with no history of headache. It also found it to a lesser extent in women with episodic migraine, according to Medscape. It said the results suggest that CGRP levels could serve as a biomarker for permanent trigeminovascular activation and so help diagnose chronic migraine.
"Can you imagine diagnosing and treating diabetes only on clinical grounds? That's what we do now in primary headaches. It's important to have biomarkers, not only to avoid misdiagnoses but also for treatment follow-up," Dr. Julio Pascual told Medscape. Pascual, director of the neuroscience department and professor of neurology at the University Hospital Central de Asturias in Oviedo, Spain, is the lead author of the new study.
During a migraine attack, trigeminal activation leads to release of CGRP from presynaptic nerve terminals. But according to Medscape, this is the first time research has found higher levels of CGRP outside migraine attacks and when patients had not taken medication for symptoms.
The study included 103 women with chronic migraine, 31 women with no history of headache, 43 women with episodic migraine (EM) and 14 patients with episodic cluster headaches. Researchers took blood samples from participants when they were not experiencing moderate or severe pain and had not taken medication for symptoms in the previous 24 hours. The patients were allowed to continue daily preventive medications if they were taking them, and most of the migraine sufferers were. Using a commercially available enzyme-linked immunosorbent assay kit, investigators checked CGRP levels.
They found that they were significantly higher in women with CM compared to the other groups and also significantly elevated in women with a history of migraine with aura compared with those experiencing migraine without aura. The authors acknowledge that more research is needed and that there were limitations to the study. But given the need and the fact that the tests are easy and inexpensive to perform, Pascual said he believes healthcare providers will soon start checking CGRP levels routinely to follow CM patients.
"My prediction is that clinical trials in chronic migraine that include the follow-up of CGRP levels will begin soon after publication of our study," he told Medscape.
This study is not the only one to look for biomarkers tied to migraine. A recent preliminary study led by Johns Hopkins determined that measuring a fat-derived protein called adiponectin before and after migraine treatment can accurately reveal which headache victims felt pain relief. They said it might provide a biomarker for tracking treatment response.