Epidemiology: For families

So, you have a headache.

The bad news is: you have a headache.

The good news is: you are not alone, and there are many things that can be done to help.

Headaches are very common, and affect children and teenagers of all ages, from across the world. Approximately half of school-aged children and 8 out of 10 teenagers have reported a bad headache at some point in their life. In the United States, about 1 out of 6 children report severe or frequent headaches within the past year. Parents often seek medical care to find out the cause of the headaches, or because headaches are affecting their child’s life.

Headache history is a key part to helping your clinician make a diagnosis. Your clinician will try to understand all the details of the headache problem, and how it affects your life. We classify headaches based on their characteristics into two general categories, secondary headaches and primary headaches. In secondary headache disorders, the headache can be thought of as a clue to the underlying problem. In primary headache, the headache is the underlying problem.

Secondary headaches are caused by another underlying problem, such as a head injury or a viral infection. After asking questions and examining you, your clinician will determine whether there are any “red flags” for a serious condition. It is very rare for a serious condition, like a brain tumor, to present with only headache. This occurs in less than 1% of children. Usually there are other symptoms or exam abnormalities.

Primary headaches are the most common category of headache in children and teens. Primary headaches are not due to another underlying medical problem. Up to three-quarters of children and teens with primary headaches will have a family history of headache. In other words, there is a genetic link to headaches. Whether a headache problem occurs, and how severe it is, can also be influenced by things in the child’s environment.

The most common primary headache disorder in children and teens is tension-type headache . This affects at least 1 in 4 children in their lifetime. Tension-type headaches are often felt all over the head, and are mild to moderate in severity. The headache pain is usually the only symptom, without problems like nausea.

The most common primary headache disorder in children and teens seeking medical attention is migraine. Migraine is more than “just a headache”. The 2017 Global Burden of Diseases Study ranked migraine as the second leading cause of disability worldwide. Studies in children and teens have found that migraine affects children’s quality of life as much as diabetes, arthritis, and cancer. Migraine has been described as an invisible illness. Children and teens experiencing a migraine may appear otherwise normal to family, friends, and teachers. Although a migraine might seem invisible, behind the scenes there are important changes happening within the brain. You will read more about this in the chapter on Pathophysiology.

Migraine affects up to 5% of children and approximately 10% of teenagers. Before puberty, it is equally common in boys and girls. After puberty, more girls are affected. Less than a third of children and teens will experience aura symptoms, which are additional neurological symptoms. Most commonly, these are visual symptoms or sensory symptoms affecting one side of the face or body. These symptoms typically evolve over a few minutes, and then resolve completely. They may come before or during the pain of the migraine. Rarely, aura can involve motor weakness. This condition, called hemiplegic migraine, can run in families and accounts for only 0.01% of migraine cases in children and adolescents. Chronic migraine, where headache occurs more than half the days in a month, affects between 0.8% and 1.8% of children and adolescents. It is more common in girls and in the later teenage years. Teens with chronic migraine are more likely to report severe headache-related disability and impact on quality of life.

In summary, headaches are very common. More children will experience a headache in their lifetime than not. However, all headaches are different, and certainly not all headaches are created equal. Severe or frequent attacks can have a significant impact on day-to-day functioning, school, activities, and mood. Just because you can’t see it, doesn’t mean that it is not there . Molecular studies and functional brain imaging studies have proven that there are many complex changes happening in the brain during a migraine—stay tuned.

Epidemiology: For primary care and specialists

Headache is one of the most common conditions evaluated by healthcare providers. It is prevalent, disabling, underdiagnosed, and undertreated. The estimated mean prevalence of headache in children and adolescents varies between studies and is estimated to be up to 58.4%. Headache is more common in girls than boys, and the prevalence of headache increases from preschool age to adolescence.

Headaches are associated with substantial direct healthcare costs and resource utilization, as well as indirect costs from reduced educational and occupational productivity and quality of life. Migraine alone has an enormous impact on global economics; in 2003 migraine cost the United States $19.6 billion annually and the European Union €27 billion annually. The impact of pediatric headache is especially important to consider during the formative years of childhood and adolescence, where headaches can lead to absence from school, decreased performance, and missed extracurricular activities. The psychosocial and economic burden of headache lends urgency towards better understanding, accurately identifying, and promptly and effectively treating these disorders.

Epidemiological studies are central to understanding the burden, scope, and distribution of headache disorders in children. The lack of standardized case definitions and the heterogeneity in study methodology are among the challenges which contribute to the variability in estimates of prevalence and incidence in the literature.

As noted earlier, headache disorders are classified as primary or secondary. An additional challenge in categorizing pediatric headache using the International Classification of Headache Disorders, 3rd Edition (ICHD-3) is that headache disorders in childhood differ from their adult manifestations. Furthermore, the character of pediatric headache disorders can change over time. This may relate to developmental and maturational changes in the brain, such as myelination and synaptic development and reorganization. The two most common primary headache disorders in children are tension-type headache and migraine , and the distinction clinically between these disorders is far less clear in children than in adults.

Migraine

The literature on pediatric migraine is the most robust among the primary headache disorders in children and adolescents. In girls, the incidence of migraine with aura peaks between 12 and 13 years of age, and the incidence of migraine without aura peaks between 14 and 17 years of age. In boys, the incidence of migraine with aura peaks around 5 years of age, and for migraine without aura between 10 and 11 years of age.

Migraine affects both girls and boys equally at a young age, but more girls than boys in adolescents and young adults. The prevalence of migraine increases with age, from about 7.0% in girls and 4.7% of boys by age 15, up to 9.7% of girls and 6.0% of boys by age 20. The burden of migraine lays not only in the number of children and adolescents it affects, but also in the extent to which they are affected. During a migraine, 60.8% of adolescents report experiencing severe impairment. Evaluating severity and disability surveys, 16.8% of adolescents with migraine report scores in the range of moderate-to-severe disability.

Chronic primary headaches in children and adolescents are particularly challenging to study from an epidemiological perspective, as they can be difficult to diagnostically categorize. There are no criteria specified for children and adolescents for chronic migraine. Since symptoms in children and adolescents can be different than adults, children with chronic headache may not meet the ICHD-3 criteria for a specific headache subtype. The prevalence of chronic migraine in adolescents (ages 12–17) is between 0.8% and 1.8%, with a female preponderance and a peak in the later teenage years. The majority of adolescents surveyed with chronic migraine indicated severe headache-related disability and impact on quality of life. Notwithstanding the degree of impairment, more than half of chronic migraine patients reported they had not seen a healthcare professional for their headaches in the past year.

Migraine is a complex genetic disorder, influenced by both environmental and genetic factors. Most familial migraine results from polygenic changes. Research in genome-wide association studies have revealed many different variants involving genes with roles in both neuronal and vascular pathways. More work is needed to evaluate gene expression and epigenetic factors to better understand how the genetic architecture relates to migraine pathophysiology.

A positive family history of migraine is the most impactful risk factor for migraine, conferring a two-fold to three-fold increased risk of developing migraine as compared to people without a family history of migraine. The actual risk may be even higher, as studies have shown that migraine assessed by family member report largely underestimates migraine in relatives. Children and adolescents with a family history of migraine tend to have an earlier onset of headache symptoms and a greater severity than those without a family history.

Twin studies and population studies have estimated that half of the variance in migraine prevalence may be attributed to genetic factors. This suggests that environmental risk factors still play an important role. In an adult population, migraine has a higher prevalence in the lower income and educational strata. Two hypotheses for this association have been considered. Firstly, in the social causation hypothesis, it is thought that factors relating to lower income such as poor diet, stress, and barriers to accessing healthcare may increase disease prevalence. Conversely, in the social selection hypothesis, those with migraine may be more likely to have a lower income status due to disease-related dysfunction and the downstream effect this has on educational and occupational performance and outcomes.

In adolescents, the same observation holds true only when there is not a parental diagnosis of migraine. With a parental diagnosis of migraine, household income does not have a significant effect on migraine prevalence. This is a curious observation and may suggest that in those with a family history of migraine the biologic predisposition predominates and income strata does not have as strong of a modifying effect.

Several studies have shown a correlation between adverse childhood experiences (ACEs) and headaches. This has been established as a risk factor for early onset and chronicity of headaches in adolescents, and this relationship is independent of a diagnosis of an anxiety disorder or depression.

In terms of healthcare utilization in children and adolescent headache, there is often a delay to seeking medical care, and an even greater delay to seeking specialist headache care. A recent study showed that less than 5% of children with migraine who qualified for the use of a preventive medication were started on one while awaiting a neurology referral, and none had been started on a triptan by their primary care physician. Further study evaluating prescribed medications in children with migraine in the United States suggested that more than half were under the care of pediatricians; and less than a quarter were being treated by a neurologist. These findings further emphasize the need for ongoing education among patients, families, and healthcare providers, as inadequate treatment of pediatric migraine is associated with disease progression and chronification.

Tension-type headache

Tension-type headache is the most common primary headache disorder in children and adolescents. There is a wide range in the reported prevalence, from 5% to 25%. The mean age of onset is 7 years old and attack duration is variable, with an average duration of 2 h. Headaches often begin in the afternoon at school. In children, tension-type headache has been postulated to be related to many different risk factors, including psychosocial stressors, musculoskeletal pathology, oro-mandibular dysfunction, or anxiety or depression.

Trigeminal autonomic cephalalgias

Trigeminal autonomic cephalalgias (TACs) are subdivided into: paroxysmal hemicrania, cluster headache; short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT); short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA); and hemicrania continua. These syndromes rarely begin in childhood, and if present, would warrant further workup to exclude for secondary causes. Cluster headache begins in adolescents in a minority of patients (0.03%–0.1%) and has a male predominance of 2.5:1.

Other primary headache disorders

Primary stabbing headache has a prevalence of 3%–5% in children and is associated with a higher incidence of co-morbid migraine or tension-type headache. Other primary headache disorders—such as primary cough headache, primary exercise headache, primary headache associated with sexual activity, and primary thunderclap headache—should be diagnosed in children and adolescents only after appropriate exclusion of a secondary etiology.

New daily persistent headache

New daily persistent headache (NDPH) has a prevalence in the general population of 0.03%–0.1% and is higher in children and adolescents. Among children and adolescents with chronic daily headache, the prevalence of NDPH is 21%–28%. Most children will report a precipitating event such as a febrile illness or minor head injury.

Secondary headache

Secondary headaches in children include headaches attributed to: injury to the head and neck; cranial or cervical vascular disorders; non-vascular intracranial disorders; substance use or withdrawal; infection; disorders of homeostasis; disorders of the head and neck; and psychiatric disorders. The most common cause of secondary headache in children is viral illness. Less than 2.5% of children who undergo neuroimaging to exclude a secondary intracranial cause for headache, are found to have any actionable abnormalities. As per the Childhood Brain Tumor Consortium, less than 1% of children with brain tumors present with headache alone, in the absence of other symptoms or signs.

Understanding the classification of headache disorders and evaluating the epidemiological patterns can help identify those groups at highest risk. Evaluating the genetic, environmental, and sociodemographic factors contributing to different types of headache disorders can further provide clues towards better understanding the disease mechanisms and determining the optimal treatment strategies.