Why do migraines happen

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Last updated: April 8, 2026

Quick Answer: Migraines occur due to complex neurological processes involving abnormal brain activity, genetic factors, and environmental triggers. Approximately 1 billion people worldwide experience migraines, with women being three times more likely than men to suffer from them. The condition costs the U.S. economy an estimated $36 billion annually in healthcare expenses and lost productivity. Research from 2020 identified specific genetic variants associated with migraine susceptibility, highlighting its hereditary nature.

Key Facts

Migraines affect about 1 billion people globally according to 2021 WHO data
Women experience migraines 3 times more frequently than men
Migraines cost the U.S. economy approximately $36 billion annually
The first documented descriptions of migraine symptoms date back to 3000 BCE in ancient Egyptian texts
About 50% of migraine sufferers have a family history of the condition

Overview

Migraines are a complex neurological disorder characterized by recurrent, severe headaches often accompanied by sensory disturbances. Historically documented since ancient times, with descriptions appearing in Egyptian medical texts from 3000 BCE and later detailed by Hippocrates in 400 BCE, migraines have evolved in medical understanding from supernatural explanations to recognized biological conditions. The International Classification of Headache Disorders (ICHD-3), established in 2018, categorizes migraines into several types including migraine with aura and migraine without aura. Globally, migraines rank as the second leading cause of disability worldwide according to 2019 Global Burden of Disease data, affecting people across all demographics but with significant gender disparities. The economic impact is substantial, with migraine-related costs including direct medical expenses and indirect costs from lost work productivity.

How It Works

Migraine pathophysiology involves a cascade of neurological events beginning with cortical spreading depression (CSD), a wave of neuronal depolarization that spreads across the brain cortex at 2-3 mm per minute. This triggers the release of inflammatory neuropeptides like calcitonin gene-related peptide (CGRP), which causes dilation of cranial blood vessels and activates pain pathways through the trigeminal nerve system. Genetic factors play a crucial role, with over 40 identified genetic loci associated with migraine susceptibility, including genes involved in neuronal excitability and vascular function. Environmental triggers such as stress (reported by 80% of sufferers), hormonal changes (particularly estrogen fluctuations), specific foods (like aged cheeses and processed meats containing tyramine), and sensory stimuli (bright lights, loud sounds) can initiate attacks. The pain phase involves sensitization of central and peripheral pain pathways, while accompanying symptoms like nausea and photophobia result from brainstem activation.

Why It Matters

Migraines have profound real-world impacts extending beyond individual suffering. They represent a major public health concern, causing approximately 157 million workdays lost annually in the United States alone. The condition significantly reduces quality of life, with migraine sufferers experiencing 50% more disability days than non-sufferers. Recent therapeutic advances, particularly CGRP-targeting medications approved by the FDA since 2018, have revolutionized treatment but highlight ongoing healthcare disparities in access. Understanding migraine mechanisms has broader implications for neuroscience, contributing to knowledge about pain processing, neurovascular interactions, and genetic influences on neurological disorders. The economic burden underscores the need for effective prevention and management strategies in healthcare systems worldwide.