In 158 migraine patients, anti-CGRP antibodies reduced light sensitivity, sound sensitivity, and aura at a faster rate than headache days themselves, suggesting CGRP plays a direct role in these symptoms beyond just causing pain.
-19.5% photophobia ratioLight sensitivity decreased at a higher rate than headache days in responders, and worse baseline photophobia predicted better treatment response
What the researchers found
Of 158 patients, 44% achieved a 50% or greater reduction in headache days at month 6. In this responder group, headache days decreased by 9.4 days/month (p<0.001). Beyond headache reduction, the ratio of days with specific symptoms decreased significantly:
- Photophobia: -19.5% (p<0.001)
- Phonophobia: -12.1% (p=0.010)
- Aura: -25.1% (p=0.008)
These reductions exceeded the proportional decrease in headache days, meaning the symptoms improved independently, not just because there were fewer migraines. Nausea and dizziness decreased only in proportion to fewer headache days. Higher baseline photophobia ratios predicted better response between months 3-6 (IRR=0.928, p=0.040), suggesting CGRP's role in light sensitivity may identify patients likely to benefit.
Why it matters
Clinical trials of anti-CGRP antibodies focused almost exclusively on headache day reduction, largely ignoring the accompanying symptoms that migraine patients often describe as equally disabling. This study shows these drugs do more than just reduce headache frequency — they specifically improve sensory symptoms like light sensitivity and aura, suggesting CGRP has a direct role in these experiences. This is clinically important because patients with prominent photophobia may be particularly good candidates for anti-CGRP therapy.
How the study worked
This was a prospective real-world study at a headache clinic. 158 migraine patients treated with erenumab, galcanezumab, or fremanezumab completed daily electronic diaries tracking headache frequency and accompanying symptoms (photophobia, phonophobia, nausea, dizziness, aura). Symptom ratios were calculated relative to headache days at baseline, 3 months, and 6 months. Responders (≥50% headache reduction) were compared to non-responders.
What this study cannot tell us
This was an observational real-world study without a placebo control, so some symptom improvement could reflect placebo effects or natural disease fluctuation. The sample size of 158 limits subgroup analyses. Symptom assessment relied on patient-reported eDiaries, which may have recording biases. The 6-month follow-up may not capture longer-term effects. The three different anti-CGRP antibodies were analyzed together rather than separately.
How to read the evidence
This is a prospective observational real-world evidence study with electronic diary tracking — more rigorous than retrospective studies but lacking a placebo control. The 158-patient sample provides moderate statistical power.
When this study was published
Published in 2023, this study captures real-world outcomes with established anti-CGRP therapies and addresses a gap in the clinical trial literature about accompanying symptoms.
The bigger picture
CGRP is released by sensory neurons and was known to be involved in pain signaling, but its role in migraine's sensory symptoms (photophobia, phonophobia, aura) was less well understood. This study provides real-world evidence that blocking CGRP affects these symptoms independently of headache reduction, suggesting CGRP contributes to the broader migraine syndrome beyond just pain. The finding that anti-CGRP antibodies — which primarily work in the peripheral nervous system — can reduce aura (a central nervous system phenomenon) hints at peripheral-central CGRP crosstalk.
Questions still open
- Does photophobia at baseline serve as a reliable biomarker for predicting anti-CGRP antibody response in clinical practice?
- How do anti-CGRP antibodies reduce aura, given that aura is thought to originate in the brain cortex where these antibodies have limited access?
Common questions
Do anti-CGRP drugs help with light sensitivity, or just the headache?
Can my light sensitivity predict whether anti-CGRP drugs will work for me?
Read the original research
Impact of anti-CGRP monoclonal antibodies on migraine attack accompanying symptoms: A real-world evidence study.
Cephalalgia : an international journal of headache, 43(8), 3331024231177636
Citation
Alpuente, Alicia; Torre-Sune, Anna; Caronna, Edoardo; Gine-Cipres, Eulalia; Torres-Ferrús, Marta; Pozo-Rosich, Patricia. (2023). Impact of anti-CGRP monoclonal antibodies on migraine attack accompanying symptoms: A real-world evidence study.. Cephalalgia : an international journal of headache, 43(8), 3331024231177636. https://doi.org/10.1177/03331024231177636