A study published in the journal Scientific Reports has categorized migraine-associated odors into six groups and observed that odors of cleaning products can significantly increase migraine attacks in patients with chronic migraines.

Study: Classification of odors associated with migraine attacks: a cross-sectional study. Image Credit: fizkes/Shutterstock.com

Background

Migraine is a common neurological disease characterized by strong headache, typically on one side of the head. In Japan, the prevalence of migraine is 8.4%. Certain factors, including stress, fasting, weather, sleep disturbance, hormones in women, light, sound, and odors, are known to increase migraine attacks.

Increased sensitivity to odor is considered a specific symptom of migraine, which is frequently observed in 95% of migraine patients. There is evidence showing that certain types of odors are particularly associated with migraine attacks.

Mechanistically, odor signal is received by the brain through the olfactory bulb, and studies have shown that odors trigger migraine by activating different brain regions.

In the current study, scientists have categorized migraine-associated odors and determined their correlation with clinical characteristics.

Study design

The study was conducted on a total of 101 patients with clinical migraine. The participants were provided with a questionnaire comprising 35 items of odors selected based on previous evidence.

The questionnaire was used to determine which types of odors triggered migraine attack and how the participants protected themselves from the odors.

Furthermore, the scientists conducted a factor analysis to determine common factors of odors associated with migraine attacks. Factor analysis is a statistical method that reduces a large set of variables into a smaller set of factors by extracting all commonalities from the variables.

Important observations

About 16% and 84% of the study population were present with chronic and episodic migraine, respectively. Among participants with chronic migraine, 75% had concomitant medication overuse headache. An association between odor and migraine attack was observed in 78% of participants.

More than 50% of participants reported perfume odor as a trigger of migraine attack. This was followed by odors of tobacco, fabric softener, body, garbage, hairdressing product, automobile, and sweat. None of the participants reported lemon, tangerine, or apple odor as a migraine trigger.

Apart from 35 items of odors included in the questionnaire, ikebana (a Japanese art of flower arrangement) and gasoline were the most commonly reported odors associated with migraine attack.

Besides types of odors, the study determined common places associated with migraine attack. More than 50% of the participants reported office as a common place related to migraine attack.

This was followed by home, restaurant, and hospital waiting room. None of the participants identified consultation or examination room as a place associated with migraine attack.

Apart from migraine-associated locations included in the questionnaire, train, town, and departmental stores were the most commonly reported places associated with migraine attack.

Regarding preventive measures against odors, about 42%, 23%, and 22% of the participants reported wearing mask, using air cleaner, and using deodorant spray, respectively. In addition, about 17% and 5% of the participants reported moving out of the place and covering the nose with a handkerchief, respectively, to prevent odors.

Considering participant’s age, a significantly high rate of migraine attack due to tobacco or soap odor was observed among younger participants. Considering gender, migraine attack due to body odor or garbage was observed only in female participants.

Considering types of migraine, participants with chronic migraine showed higher susceptibility to fabric softener, sweat, socks, coffee, excrement, vomit, and animal odors compared to those with episodic migraine.

Based on the factor analysis, six common factors of the odors were identified. Factor one was fetid odor; factor two was cooking products; factor three was oil derivatives and others; factor four was shampoo and conditioner; factor five was cleaning products; and factor six was perfumes, insecticides, and rose.    

Factor five, which also included flora-based hair styling preparations, laundry detergents, and fabric softeners with floral fragrances, showed significantly higher association with migraine attacks in chronic migraine patients than that in episodic migraine patients.

Study significance

The study identifies six groups of odorant substances that can trigger migraine attack in patients with chronic or episodic migraine.

However, chronic migraine patients can have higher susceptibility to some chemicals with floral fragrance.

Written by

Dr. Sanchari Sinha Dutta

Dr. Sanchari Sinha Dutta is a science communicator who believes in spreading the power of science in every corner of the world. She has a Bachelor of Science (B.Sc.) degree and a Master's of Science (M.Sc.) in biology and human physiology. Following her Master's degree, Sanchari went on to study a Ph.D. in human physiology. She has authored more than 10 original research articles, all of which have been published in world renowned international journals.