Epilepsy Across Demographics: How Subtype Prevalence Varies in Different Populations
By Amanda Nascimento
Introduction
Epilepsy is a neurological disorder that affects individuals of all ages, races, and genders. However, the prevalence and presentation of epilepsy subtypes can vary significantly across different demographic groups. Understanding these variations is crucial for improving diagnosis, treatment, and management strategies. Factors such as age, gender, ethnicity, and socio-economic status can influence not only the likelihood of developing epilepsy but also the type of seizures experienced. This article explores how epilepsy subtypes vary across different populations and the implications for healthcare professionals and patients.
Epilepsy Subtypes and Their General Prevalence
Epilepsy is broadly classified into focal (or partial) and generalized epilepsy based on the origin of seizure activity in the brain. Focal seizures begin in a specific part of the brain, while generalized seizures involve both hemispheres. These two types are further subdivided into various subtypes, such as absence epilepsy, tonic-clonic seizures, and myoclonic epilepsy.
According to the World Health Organization (WHO), around 50 million people worldwide suffer from epilepsy, with about 80% of cases occurring in low- and middle-income countries. Globally, focal seizures tend to be more common than generalized ones, but this prevalence can change depending on the population group.
Age-Related Differences in Epilepsy Subtypes
Age is one of the most significant factors in determining the prevalence of certain epilepsy subtypes. Childhood epilepsy, for example, often presents with generalized seizures, such as absence epilepsy and juvenile myoclonic epilepsy (JME). Absence epilepsy is most commonly diagnosed between the ages of 4 and 10 and is characterized by brief lapses in consciousness, often referred to as “absence seizures” (Mayo Clinic, 2020).
On the other hand, older adults are more likely to experience focal seizures, often due to underlying causes such as stroke, brain tumors, or neurodegenerative diseases. In fact, epilepsy in individuals over the age of 60 is often secondary to conditions like Alzheimer’s disease or vascular disease (Sen et al., 2020). The aging brain is more susceptible to focal epilepsy due to increased vulnerability to injuries and neurodegeneration.
Gender Differences in Epilepsy Prevalence
Gender also plays a role in the manifestation and prevalence of different epilepsy subtypes. Studies have shown that men are slightly more likely to develop epilepsy than women, although the difference is small (Banerjee et al., 2009). However, specific epilepsy syndromes display gender-based prevalence. For instance, juvenile myoclonic epilepsy (JME) tends to be more prevalent in women, while focal epilepsy related to traumatic brain injury or brain lesions is more common in men (Sillanpää & Schmidt, 2006).
Hormonal fluctuations, especially during puberty, pregnancy, and menopause, can significantly impact seizure frequency and type in women. Catamenial epilepsy, a condition where seizures become more frequent around the menstrual cycle, highlights the influence of estrogen and progesterone on epilepsy in women (Herzog, 1997). This hormonal sensitivity can result in different treatment needs and seizure management strategies for women compared to men.
Ethnic and Geographic Variations
Ethnicity and geographic location also play an important role in the prevalence of epilepsy subtypes. For example, genetic epilepsies are more frequently diagnosed in individuals of European descent, particularly subtypes like Dravet syndrome and juvenile myoclonic epilepsy. Studies suggest that some genetic predispositions to epilepsy may be more common in certain ethnic groups due to historical evolutionary pressures or population-specific genetic variants (Helbig et al., 2008).
In sub-Saharan Africa and South Asia, focal epilepsy due to infectious diseases, such as neurocysticercosis (a parasitic infection of the central nervous system), is much more common than in Western populations. Neuroinfections, including malaria, tuberculosis, and HIV, are significant causes of epilepsy in these regions. In these areas, epilepsy is often underdiagnosed and untreated due to limited access to healthcare services and stigma surrounding the condition (WHO, 2019).
In contrast, epilepsy due to traumatic brain injury is more prevalent in regions with higher rates of violence or road traffic accidents, such as parts of Latin America and the Middle East (de Bittencourt et al., 1996). This trauma-induced epilepsy primarily leads to focal seizures, highlighting how environmental factors contribute to subtype prevalence.
Socioeconomic Status and Access to Care
Socioeconomic status (SES) has a profound influence on the type of epilepsy diagnosed and the quality-of-care individuals receive. In low-income populations, focal epilepsy is often more prevalent due to increased exposure to risk factors such as head injuries, malnutrition, and infectious diseases (Ngugi et al., 2011). Moreover, in these populations, epilepsy is often not properly treated or controlled, leading to higher rates of epilepsy-related mortality.
Access to healthcare plays a pivotal role in epilepsy management, particularly in terms of receiving accurate diagnoses and appropriate treatments. In high-income countries, individuals are more likely to receive treatment that controls seizures effectively, while those in low-income regions may go untreated, leading to recurrent seizures and progressive cognitive decline (WHO, 2019). The lack of specialized neurological care in resource-poor areas can also skew the apparent prevalence of different epilepsy subtypes, as many cases go undiagnosed.
Genetic Epilepsy and Family History
Genetic factors contribute significantly to the risk of developing epilepsy, and these factors often vary by population. Idiopathic generalized epilepsy (IGE), including subtypes like childhood absence epilepsy and juvenile myoclonic epilepsy, is strongly associated with family history and genetic predisposition. These subtypes are more common in populations with a history of consanguinity or where genetic disorders are more prevalent (Helbig et al., 2008).
Mutations in genes such as SCN1A, associated with Dravet syndrome, and CACNA1A, linked to familial hemiplegic migraine and epilepsy, are more commonly diagnosed in certain populations, highlighting the role of genetics in subtype prevalence (Helbig et al., 2008).
Conclusion
The prevalence of epilepsy subtypes is influenced by a wide range of demographic factors, including age, gender, ethnicity, and socioeconomic status. Recognizing these variations is crucial for healthcare providers to offer tailored treatment and management strategies that address the specific needs of different populations. Future research focusing on the intersection of genetics, environmental factors, and access to care will be essential for reducing the global burden of epilepsy and improving outcomes for patients worldwide.
References
Banerjee, P. N., Filippi, D., & Allen Hauser, W. (2009). The descriptive epidemiology of epilepsy—a review. Epilepsy Research. doi: 10.1016/j.eplepsyres.2009.03.003
de Bittencourt, P. R. M., Adamolekum, B., Bharucha, N., Carpio, A., & Zaatreh, M. (1996). Epilepsy in the tropics: epidemiology, socioeconomic risk factors, and etiology. Epilepsia. doi: 10.1111/j.1528-1157.1996.tb01035.x.
Helbig, I., Scheffer, I. E., Mulley, J. C., & Berkovic, S. F. (2008). Navigating the channels and beyond: unravelling the genetics of the epilepsies. The Lancet Neurology. doi: 10.1016/S1474-4422(08)70039-5.
Herzog, A. G. (1997). Catamenial epilepsy: Definition, prevalence pathophysiology and treatment. Seizure. doi.org/10.1016/j.seizure.2007.11.014
Mayo Clinic. (2020). Absence seizures. Retrieved from https://www.mayoclinic.org/diseases-conditions/absence-seizure/symptoms-causes/syc-20359683.
Ngugi, A. K., Kariuki, S. M., Bottomley, C., Kleinschmidt, I., Sander, J. W., & Newton, C. R. (2011). Incidence of epilepsy: a systematic review and meta-analysis. Neurology. doi: 10.1212/WNL.0b013e31822cfc90.
Sen A, Jette N, Husain M, Sander JW. (2020). Epilepsy in older people. Lancet. 10.1016/S0140-6736(19)33064-8.
Sillanpää, M., & Schmidt, D. (2006). Natural history of treated childhood-onset epilepsy: prospective, long-term population-based study. Brain. doi: 10.1093/brain/awh726.
World Health Organization (WHO). (2019). Epilepsy. Retrieved from https://www.who.int/news-room/fact-sheets/detail/epilepsy.
