Migraine: What Could Be Causing It?

The Neurobiology Behind Migraine Attacks

Migraine is not simply a bad headache. It is a genetically influenced neurological disease involving abnormal brain excitability, neurovascular inflammation, and dysfunctional pain processing. The pathophysiology has shifted dramatically from the old "vascular theory" toward a neurovascular model centered on the trigeminovascular system.

The current understanding begins with cortical spreading depolarization (CSD), a slow wave of neuronal and glial depolarization that propagates across the cerebral cortex at 3 to 5 mm per minute. CSD is the electrophysiological substrate of aura and may also trigger headache in migraine without aura by activating meningeal nociceptors. Once triggered, CSD causes release of potassium, hydrogen ions, and ATP into the extracellular space, activating trigeminal nerve fibers that innervate the meninges [1].

These trigeminal afferents release vasoactive neuropeptides, most notably calcitonin gene-related peptide (CGRP), substance P, and pituitary adenylate cyclase-activating peptide (PACAP). CGRP has emerged as the dominant mediator. Intravenous CGRP infusion reliably provokes migraine-like attacks in susceptible individuals but not in healthy controls [2]. This finding directly led to the development of CGRP-targeted monoclonal antibodies and gepants, which represent the first migraine-specific preventive drug class in over two decades.

The signal travels from meningeal nociceptors to the trigeminal nucleus caudalis in the brainstem, then ascends to the thalamus and cortex. Functional MRI studies show that the hypothalamus activates in the premonitory phase, hours before headache onset, explaining prodromal symptoms like yawning, food cravings, and mood changes [3]. This hypothalamic involvement also helps explain why sleep disruption and circadian irregularity are such reliable triggers.

Genetic Susceptibility and Family History

Your genes set the threshold. Migraine runs in families, and twin studies estimate heritability at 30 to 60%. If one parent has migraine, a child's risk roughly doubles.

Genome-wide association studies (GWAS) have identified over 120 genetic loci associated with common migraine [4]. Most of these variants cluster around genes involved in vascular function, ion channel regulation, and synaptic signaling. The picture that emerges is one of polygenic susceptibility: dozens of small-effect variants collectively lower the threshold for cortical excitability, making the brain more reactive to internal and external triggers.

Familial hemiplegic migraine (FHM) offers a clearer genetic window. Three genes have been identified: CACNA1A (encoding a calcium channel), ATP1A2 (sodium-potassium ATPase), and SCN1A (sodium channel). Mutations in these genes cause ion channel dysfunction that increases neuronal excitability. While FHM is rare, studying these mutations has confirmed that ion channel dysregulation sits at the core of migraine biology [5].

A 2022 analysis in Nature Genetics (Hautakangas et al., N=873,341) pinpointed 123 risk loci for migraine, with enrichment in vascular and smooth muscle tissue gene expression [4]. This genetic architecture overlaps partially with other pain conditions, which may explain why migraine frequently co-occurs with fibromyalgia, irritable bowel syndrome, and temporomandibular disorders.

Common Triggers and Why They Matter

Triggers do not cause migraine. They activate attacks in a brain that is already predisposed. Understanding this distinction is clinically important because it shifts the focus from trigger avoidance alone toward reducing overall brain excitability through preventive therapy.

The American Migraine Foundation and multiple prospective diary studies identify several consistent trigger categories [6]:

Hormonal factors. Estrogen withdrawal is the most well-documented trigger. Roughly 60% of women with migraine report menstrually related attacks, typically occurring in the 2 days before through the first 3 days of menstruation [7]. The mechanism involves estrogen's modulatory effect on serotonin, CGRP, and prostaglandin pathways. Oral contraceptive pill-free intervals, perimenopause, and postpartum estrogen drops all carry increased attack risk.

Sleep irregularity. Both too little and too much sleep trigger attacks. A prospective study using actigraphy (Engstrom et al., 2013) showed that sleep fragmentation on a given night predicted migraine onset the following day [8]. The hypothalamus, which regulates sleep-wake cycles, is active during the premonitory migraine phase. Consistency of sleep timing may matter more than total sleep duration.

Stress and the let-down effect. Stress itself is reported as a trigger by approximately 70% of migraine patients. Interestingly, the period of relaxation after stress (the "let-down" period) may carry even higher risk. A diary study by Lipton et al. (2014) found that decline in perceived stress from one evening to the next was associated with a 5-fold increase in migraine odds the following day [9].

Dietary factors. Alcohol (particularly red wine), aged cheeses, processed meats containing nitrates, and artificial sweeteners are commonly cited. The evidence is mixed for many foods, and individual sensitivity varies widely. Skipping meals is a more consistent trigger than any specific food item. Caffeine has a bidirectional relationship: regular intake can reduce attack frequency, while withdrawal reliably triggers attacks within 24 hours.

Environmental stimuli. Bright or flickering light, strong odors, and barometric pressure changes are reported triggers. Photophobia between attacks (interictal photosensitivity) is present in many migraine patients, suggesting baseline differences in sensory processing rather than a purely external cause.

Migraine With Aura vs. Without Aura

About 25 to 30% of migraine patients experience aura, and the distinction carries clinical significance beyond symptom description.

Aura consists of fully reversible focal neurological symptoms that typically develop over 5 to 60 minutes and precede or accompany the headache phase. Visual aura is the most common type (occurring in over 90% of aura cases), presenting as scintillating scotoma, fortification spectra (zigzag lines), or visual field loss. Sensory aura (tingling, numbness migrating up an arm or across the face) is the second most common. Language disturbance (dysphasia) and, rarely, motor weakness (hemiplegic migraine) also occur.

The International Headache Society's ICHD-3 criteria classify migraine with aura (code 1.2) separately from migraine without aura (code 1.1) [10]. A patient can have both subtypes at different times.

The clinical importance of identifying aura includes cardiovascular risk stratification. A meta-analysis in the BMJ (Schurks et al., 2009) found that migraine with aura doubled the risk of ischemic stroke (RR 2.16 to 95% CI 1.53 to 3.03) [11]. This risk is amplified by combined oral contraceptive use and smoking. Current guidelines from the American College of Obstetricians and Gynecologists recommend against estrogen-containing contraceptives in women with migraine with aura [12].

Aura without headache (acephalgic migraine) is more common in patients over 50 and must be differentiated from transient ischemic attack (TIA). Key distinguishing features: aura symptoms build gradually over minutes (TIA symptoms are maximal at onset), aura often involves positive phenomena like scintillations (TIA typically presents with negative symptoms like vision loss), and aura duration is usually under 60 minutes.

How Migraine Is Diagnosed

Migraine is a clinical diagnosis. No blood test, imaging study, or biomarker confirms it.

The ICHD-3 diagnostic criteria for migraine without aura require at least 5 attacks lasting 4 to 72 hours (untreated), with at least two of four pain characteristics (unilateral, pulsating, moderate-to-severe intensity, aggravated by routine physical activity) and at least one associated symptom (nausea/vomiting or both photophobia and phonophobia) [10].

A thorough history is the most valuable diagnostic tool. The clinician should ask about attack frequency, duration, quality and location of pain, associated symptoms, family history, and trigger patterns. A headache diary kept for at least 4 to 8 weeks provides more reliable data than patient recall.

Neuroimaging is not routinely indicated for patients meeting migraine criteria with a normal neurological exam. The American Headache Society's Choosing Wisely recommendations advise against neuroimaging in patients with stable migraine patterns and no red flags [13]. Red flags warranting imaging include: thunderclap headache (peak intensity within seconds), new headache after age 50, headache with fever and neck stiffness, progressive worsening over weeks, focal neurological deficits that do not fit aura criteria, and headache triggered by Valsalva maneuver, coughing, or exertion.

Secondary causes that mimic migraine include cerebral venous sinus thrombosis, arteriovenous malformations, idiopathic intracranial hypertension (particularly in young women with obesity), cervicogenic headache, and medication overuse headache. This last entity deserves attention: patients using acute migraine medications on 10 or more days per month for 3 or more months can develop a chronic daily headache pattern that paradoxically worsens with continued medication use.

Acute Treatment Options

The goal of acute treatment is complete pain freedom at 2 hours, with sustained response through 24 hours and no recurrence.

Triptans remain first-line for moderate-to-severe migraine attacks. Seven triptans are available; sumatriptan 100 mg oral is the most studied. A Cochrane review found that sumatriptan 100 mg achieved pain-free status at 2 hours in 26% of patients vs. 10% placebo (NNT = 6.1) [14]. Subcutaneous sumatriptan 6 mg acts faster (onset within 10 to 15 minutes) with a 2-hour pain-free rate of approximately 50%. Triptans are contraindicated in patients with established cardiovascular disease, uncontrolled hypertension, or hemiplegic migraine.

Gepants (CGRP receptor antagonists) provide an alternative for patients who cannot tolerate or have contraindications to triptans. Ubrogepant (50 mg or 100 mg) and rimegepant (75 mg) are FDA-approved for acute treatment. In the ACHIEVE I trial (N=1,672), ubrogepant 100 mg produced 2-hour pain freedom in 21.2% vs. 11.8% placebo [15]. Unlike triptans, gepants have no vasoconstrictive effects and carry minimal risk of medication overuse headache.

Ditans (5-HT1F receptor agonists) represent another non-vasoconstrictive option. Lasmiditan 200 mg achieved 2-hour pain freedom in 32.2% vs. 15.3% placebo in the SAMURAI trial [16]. Its main limitation is CNS-related side effects (dizziness, sedation), requiring patients not to drive for 8 hours post-dose.

NSAIDs and combination analgesics are appropriate for mild-to-moderate attacks. Ibuprofen 400 mg, naproxen 500 mg, or the combination of acetaminophen/aspirin/caffeine (Excedrin Migraine) are all supported by evidence. Early treatment (within 1 hour of headache onset) substantially improves outcomes across all acute medication classes.

Antiemetics such as metoclopramide 10 mg or prochlorperazine 10 mg are useful adjuncts when nausea is prominent, and prochlorperazine alone has demonstrated efficacy comparable to sumatriptan in emergency department settings.

Preventive Strategies and Newer Therapies

Preventive therapy should be discussed with any patient experiencing 4 or more migraine days per month, or fewer attacks that cause significant disability despite optimized acute treatment.

Traditional oral preventives include beta-blockers (propranolol 80 to 240 mg/day), anticonvulsants (topiramate 50 to 100 mg/day), and antidepressants (amitriptyline 25 to 75 mg/day at bedtime). Each has level A evidence from the American Academy of Neurology/American Headache Society guidelines [17]. The choice among them is often guided by comorbidities: propranolol for coexisting hypertension or anxiety, topiramate for patients wanting weight loss (average 3 to 4% body weight reduction), amitriptyline for concurrent insomnia or tension-type headache.

CGRP monoclonal antibodies have changed preventive treatment. Four are FDA-approved: erenumab (targets the CGRP receptor), fremanezumab, galcanezumab, and eptinezumab (target the CGRP ligand). Monthly or quarterly subcutaneous injections reduce migraine days by 3 to 5 per month in episodic migraine and by 4 to 8 days in chronic migraine. In the STRIVE trial (N=955), erenumab 140 mg reduced monthly migraine days by 3.7 vs. 1.8 for placebo [18]. Side effects are generally mild (injection site reactions, constipation with erenumab). Long-term open-label extension data now extend beyond 5 years for several agents.

OnabotulinumtoxinA (Botox, 155 units across 31 injection sites every 12 weeks) is FDA-approved specifically for chronic migraine. The pooled PREEMPT trials (N=1,384) showed a reduction of 8.4 headache days per 28-day cycle vs. 6.6 for placebo at 24 weeks [19]. It is not effective for episodic migraine.

Neuromodulation devices offer drug-free options. The single-pulse transcranial magnetic stimulator (sTMS), external trigeminal nerve stimulator (Cefaly), non-invasive vagus nerve stimulator (gammaCore), and remote electrical neuromodulation device (Nerivio) all have FDA clearance. Evidence quality varies, but these devices fill a gap for patients who prefer non-pharmacological approaches or have failed multiple medications.

When to Worry: Red Flags That Require Urgent Evaluation

Most migraine is benign. But headache can also signal serious pathology, and knowing when to escalate is critical.

The SNOOP mnemonic (developed by Dodick, 2003) provides a structured red flag assessment [20]:

• Systemic symptoms (fever, weight loss, malignancy, HIV) or systemic disease
• Neurological symptoms or signs (confusion, altered consciousness, focal deficits not consistent with typical aura)
• Onset that is sudden or thunderclap (reaching maximum intensity in under 60 seconds, raising concern for subarachnoid hemorrhage)
• Older age at onset (new headache after age 50 warrants evaluation for giant cell arteritis or intracranial mass)
• Pattern change (progressive worsening, positional worsening, or headache that wakes from sleep)

Any patient presenting with thunderclap headache needs emergent non-contrast CT followed by lumbar puncture if the CT is negative, to rule out subarachnoid hemorrhage. The sensitivity of CT for subarachnoid hemorrhage is approximately 98% within 6 hours of onset but drops to around 93% at 24 hours.

New daily persistent headache (NDPH), a headache that begins one day and never remits, requires MRI with and without gadolinium plus MR venography to exclude cerebral venous thrombosis. Headache with papilledema raises concern for idiopathic intracranial hypertension, an entity more common in women of childbearing age with elevated BMI.

For established migraine patients, the emergence of new features (such as aura in a patient who previously had migraine without aura, or a shift in laterality) should prompt reassessment rather than automatic attribution to migraine.

Lifestyle and Non-Pharmacological Interventions

Regular aerobic exercise at moderate intensity (30 to 40 minutes, 3 to 5 times weekly) has preventive efficacy comparable to topiramate in a randomized controlled trial by Varkey et al. [21]. The mechanism likely involves modulation of endorphin, serotonin, and brain-derived neurotrophic factor (BDNF) levels.

Cognitive behavioral therapy (CBT) for headache management has strong evidence, particularly when combined with pharmacotherapy. A randomized trial found CBT plus amitriptyline was superior to either intervention alone for chronic migraine [22]. Mindfulness-based stress reduction (MBSR) programs have shown a reduction of approximately 1.6 migraine days per month compared to usual care in a 2024 JAMA Internal Medicine trial [23].

Sleep hygiene deserves specific attention. Consistent sleep and wake times (including weekends) reduce attack frequency. Obstructive sleep apnea screening should be considered in patients with morning migraine, snoring, or obesity. Treatment of comorbid sleep disorders often reduces migraine burden independent of other interventions.

Dietary approaches should avoid overly restrictive elimination diets, which lack strong evidence and can reduce quality of life. The most evidence-backed supplements include magnesium (400 to 600 mg daily of magnesium oxide or citrate), riboflavin (400 mg daily), and coenzyme Q10 (300 mg daily). The American Headache Society considers magnesium and riboflavin "probably effective" based on available trials [17].

Patients averaging 2 or more caffeine servings daily who experience weekend or vacation migraine should evaluate whether caffeine withdrawal contributes to their pattern. Gradual reduction over 2 weeks, rather than abrupt cessation, minimizes withdrawal headache.