What Causes Migraines? The Complete Neuroscience Guide

Migraine affects an estimated 1.04 billion people worldwide and is a leading cause of years lived with disability, especially in people aged 15 to 49 (GBD 2016 Headache Collaborators, 2018; Saylor & Steiner, 2018). It is extremely common, highly disabling, and still frequently under-diagnosed or under-treated.

If you live with migraine, you already know it is not "just a headache." But understanding why migraine happens can be genuinely useful. The more accurately you understand the biology, the easier it becomes to track patterns, recognize early symptoms, and have better conversations with clinicians.

The Old Theory Was Incomplete: Migraine Is Not Just a Blood-Vessel Problem

For decades, migraine was explained mainly as a vascular disorder: blood vessels were thought to constrict first and then dilate, creating the attack. That model captured part of the story, but it does not explain the full range of migraine symptoms, especially premonitory symptoms, aura, sensory hypersensitivity, postdrome, and the way attacks can evolve over time.

Modern reviews describe migraine as a neurovascular disorder of sensory processing and brain-network dysfunction. Brain excitability, cortical signaling, hypothalamic and brainstem networks, trigeminovascular activation, and vasoactive neuropeptides all contribute to the attack process (Charles, 2018; Brennan & Pietrobon, 2018; Goadsby et al., 2017).

The Modern Understanding: Migraine Is a Multi-Phase Brain Event

Contemporary migraine science describes migraine as a multi-phase neurologic event rather than a simple pain episode. Different symptoms can appear before, during, and after the headache phase because multiple brain systems are involved across the course of an attack (Dodick, 2018; Brennan & Pietrobon, 2018).

Phase 1: The Prodrome (Hours to Days Before the Attack)

Many people with migraine notice premonitory symptoms before pain begins. These can include fatigue, frequent yawning, food cravings, irritability, difficulty concentrating, neck discomfort, and changes in thirst, appetite, or urination. In review literature, the premonitory phase can begin as early as a few hours - or even up to a few days - before head pain.

Current evidence points to networks that include the hypothalamus and brainstem nuclei involved in homeostasis and nociceptive control. That fits the clinical picture: this phase often involves changes in sleep, appetite, energy, and autonomic regulation before headache pain fully emerges (Dodick, 2018; Brennan & Pietrobon, 2018).

Phase 2: Cortical Spreading Depression (The Aura)

About one-third of people with migraine experience aura in at least some attacks. Aura usually involves visual symptoms, but it can also include sensory symptoms or language disturbance that gradually spread over minutes.

The leading mechanistic explanation is cortical spreading depression (CSD): a slowly propagating wave of cortical depolarization followed by suppressed neural activity. This model explains the "marching" nature of aura symptoms much better than the older idea of isolated blood-vessel spasm (Charles, 2018; Dodick, 2018).

As cortical activity changes across different brain regions, a person may see scintillations or blind spots, then experience tingling or language symptoms depending on the area involved.

CSD is also relevant beyond aura, because cortical excitability and downstream pain signaling help connect aura biology with the later headache phase.

Phase 3: Trigeminovascular System Activation (The Headache)

The headache phase is strongly linked to the trigeminovascular system: meningeal nociceptors, trigeminal afferents, the trigeminocervical complex, thalamic relay pathways, and higher-order sensory processing networks. This is where migraine pain, sensory amplification, and autonomic symptoms start to feel clinically obvious.

Here is what happens at the molecular level:

1. Trigeminal activation: Nociceptive pathways connected to the meninges and craniofacial structures become activated

2. CGRP release: Activated trigeminal fibers release neuropeptides, most importantly calcitonin gene-related peptide (CGRP)

3. Peripheral and central sensitization: CGRP and related signaling amplify pain transmission and contribute to the sensitized migraine state (Edvinsson et al., 2018)

4. Pain signal transmission: Signals travel through the trigeminocervical complex to the thalamus and cortex, where head pain and accompanying sensory symptoms are consciously experienced

5. Allodynia and sensory gain: As sensitization builds, normally non-painful input such as scalp touch, glasses pressure, or ordinary light can become uncomfortable or painful

This is one reason migraine is increasingly described as a disorder of sensory gain or sensory processing, not just pain. By the time light, sound, movement, and touch all feel amplified, the attack is affecting multiple sensory circuits at once (Goadsby et al., 2017; Brennan & Pietrobon, 2018).

Phase 4: The Postdrome (The "Migraine Hangover")

Pain relief does not always mean the attack is fully over. Many people report a postdrome marked by fatigue, cognitive slowing, mood change, sensory sensitivity, or a "washed out" feeling after the worst pain resolves. Review literature treats this as a real part of the migraine attack rather than a vague after-effect (Dodick, 2018).

The Threshold Model: Why Triggers Do Not Work the Same Way Every Day

One of the most useful ways to think about migraine is the threshold model. It is a clinical framework, not a lab test: your brain has a changing level of vulnerability, and attacks become more likely when several biologic stressors stack together.

That helps explain why the same trigger can matter on one day and not on another. For example:

• a missed meal might not cause a migraine on a calm, well-rested day
• the same missed meal may matter much more when it combines with poor sleep, hormonal change, stress, dehydration, or sensory overload
• "let-down" after stress can be as important as stress itself

The goal is not to blame a single exposure every time. The goal is to understand the pattern of cumulative load that lowers your threshold.

This explains several puzzling aspects of migraines:

• Why the same trigger doesn't always cause an attack — it depends on what other factors are also present
• Why migraines seem unpredictable — the threshold fluctuates and triggers combine in different ways
• Why lifestyle regularity helps — by keeping baseline stress factors low, you raise the effective threshold
• Why hormonal migraines are so reliable for some people — hormonal fluctuation can be a strong and repeated threshold-lowering factor

Genetic Factors: Why Migraine Often Runs in Families

Migraine clearly runs in families, but common migraine is usually polygenic, not a single-gene disorder. A large genome-wide analysis of 102,084 migraine cases identified 123 susceptibility loci, including loci related to CGRP biology and serotonin 1F signaling (Hautakangas et al., 2022).

Key genetic findings:

• Many risk variants are small-effect variants that add up rather than acting like a single on/off switch
• Both vascular and central nervous system tissues show enrichment, which supports the current neurovascular model
• Rare monogenic forms, such as familial hemiplegic migraine, helped clarify the importance of ion transport and cortical excitability
• Genetics influence vulnerability, not destiny - environment, sleep, stress, hormones, and treatment still matter

The current genetic picture fits what clinicians see in practice:

• migraine is biologically real
• migraine has shared mechanisms across different subtypes
• migraine is best understood as a disorder that involves both the brain and vascular signaling rather than one or the other alone

The Brain Systems Most Often Discussed in Migraine Research

Modern migraine reviews repeatedly return to a few overlapping systems:

• Hypothalamus: linked to sleep, appetite, thirst, circadian patterning, and premonitory symptoms
• Cortex: central to cortical spreading depression and aura-related phenomena
• Trigeminovascular system: the pain pathway connecting meningeal nociception to central pain processing
• Brainstem networks: involved in nociceptive modulation, arousal, and sensory gating
• Thalamocortical pathways: important for how pain and sensory amplification are experienced consciously

Together, these systems explain why migraine can involve light sensitivity, noise sensitivity, nausea, fatigue, cognitive slowing, and neck discomfort - not only head pain.

Common Triggers and How They May Work

While triggers are covered in depth in our 15 Most Common Migraine Triggers article, here is a brief look at why common triggers affect the migraine brain:

Why the CGRP Pathway Matters Clinically

One of the most important translational discoveries in migraine science is the role of CGRP. CGRP is not the only molecule involved in migraine, but it is important enough that it became a major therapeutic target (Edvinsson et al., 2018).

That matters because it changed treatment strategy. Instead of treating migraine only with broad, non-specific drugs borrowed from other fields, clinicians now have migraine-specific approaches built around the biology of the trigeminovascular system.

Examples include:

• CGRP monoclonal antibodies used for prevention
• Oral CGRP receptor antagonists (gepants) used for acute treatment, prevention, or both in selected patients

This does not mean everyone with migraine needs the newest therapy. It means the science is strong enough to support more targeted treatment discussions, especially for people with frequent, disabling, or treatment-resistant attacks.

What This Means for You

Understanding migraine biology changes how people interpret their symptoms:

1. Migraine is a real biologic disease. It is not a personality flaw, a lack of resilience, or "just stress."

2. Symptoms before the headache still count. Yawning, neck discomfort, food cravings, mood change, and sensory sensitivity may be part of the same attack.

3. Patterns matter more than single triggers. A missed meal or a bad night of sleep is often most meaningful when it stacks with other threshold-lowering factors.

4. Early recognition is useful. The earlier you recognize your own migraine pattern, the easier it is to use diaries, behavioral strategies, or acute treatment plans more effectively.

5. Frequent or disabling migraine deserves a treatment conversation. If migraine is repeatedly disrupting work, school, family life, or recovery time, that is enough reason to discuss a fuller plan with a clinician. Our MIDAS Calculator can help you quantify that burden before an appointment.

References

1. Brennan KC, Pietrobon D. A systems neuroscience approach to migraine. Neuron. 2018;97(5):1004-1021. PMC

2. Saylor D, Steiner TJ. The Global Burden of Headache. Semin Neurol. 2018;38(2):182-190. PubMed

3. GBD 2016 Headache Collaborators. Global, regional, and national burden of migraine and tension-type headache, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet Neurol. 2018;17(11):954-976. PubMed

4. Goadsby PJ, Holland PR, Martins-Oliveira M, et al. Pathophysiology of Migraine: A Disorder of Sensory Processing. Physiol Rev. 2017;97(2):553-622. PubMed

5. Dodick DW. A phase-by-phase review of migraine pathophysiology. Headache. 2018;58(Suppl 1):4-16. PubMed

6. Charles A. The pathophysiology of migraine: implications for clinical management. Lancet Neurol. 2018;17(2):174-182. PubMed

7. Edvinsson L, Haanes KA, Warfvinge K, et al. CGRP as the target of new migraine therapies - successful translation from bench to clinic. Nat Rev Neurol. 2018;14(6):338-350. PubMed

8. Hautakangas H, Winsvold BS, Ruotsalainen SE, et al. Genome-wide analysis of 102,084 migraine cases identifies 123 risk loci and subtype-specific risk alleles. Nat Genet. 2022;54(2):152-160. PubMed

This article is based on peer-reviewed research and clinical guidelines. It is for educational purposes only and does not constitute medical advice. Consult a qualified healthcare provider for diagnosis and treatment of migraines.