- Researchers looked into hypertension and epilepsy.
- Antihypertensive drugs reduce the risk of epilepsy by roughly 2.5 times.
- Researchers need to do more research to understand how elevated blood pressure affects epilepsy.
After stroke and dementia, epilepsy is the third most frequent neurological condition that affects the elderly.
Late-onset epilepsy has become increasingly common in the previous two decades, according to research. As the population ages, the number of people suffering from epilepsy is projected to climb, and epilepsy will likely become a major public health condition.
Despite this, the fundamental causes of epilepsy are unknown in 32–48% of patients. According to some evidence, vascular risk factors may raise the likelihood of late-onset epilepsy. Other research suggests that vascular risk factors play a role in epilepsy in people in their 30s.
Understanding the significance of vascular risk factors in late-onset epilepsy could aid policymakers in developing public health initiatives and prevention efforts to reduce and manage the condition’s prevalence.
Researchers from Boston University School of Medicine in the United States recently undertook a study to look at the link between vascular risk factors and epilepsy onset.
They discovered that hypertension was linked to a nearly 2-fold increased incidence of late-onset epilepsy. This risk was even higher for people who did not take blood pressure medication to control it.
The research was published in the journal Epilepsia.
The Framingham Heart Study (FHS), a community-based study that began in 1948, was utilised by the researchers. Its Offspring Cohort follows the health results of 5,124 of the initial participants’ offspring over the course of four years, based on health examinations.
The researchers collected data from 2,986 people who had their fifth assessment between 1991 and 1995, were at least 45 years old at the time, and had vascular risk factor data in their health records.
Systolic and diastolic blood pressure were among the vascular risk indicators gathered. High blood pressure was defined by the researchers as a systolic blood pressure of 140 mm Hg or higher, and a diastolic blood pressure of 90 mm Hg or higher, as well as the usage of antihypertensive drugs.
In addition, the researchers looked for:
- cholesterol levels
- smoking status
- cardiovascular disease
- body mass index (BMI)
The researchers employed routine record checks for neurological diseases, self-reported seizures, International Classification of Diseases Ninth Revision (ICD-9) codes linked to epilepsy or seizures, and antiepileptic drug use to screen subjects for epilepsy or seizures.
To determine cases of epilepsy, the researchers used brain imaging and electroencephalography (EEG), as well as cardiac and other pertinent data.
The study found 55 cases of epilepsy in the group, with 26 cases being confirmed, 15 being probable, and 14 being suspected. At the time of potential diagnosis, the participants were on average 73.8 years old.
Hypertension was linked to a nearly 2-fold increased incidence of epilepsy, according to the study. The other risk factors, on the other hand, had no link to epilepsy.
After removing antihypertensive drugs out of the equation, the researchers discovered that high blood pressure was linked to a 2.44-fold increased risk of having epilepsy.
They also discovered that every 10 mm Hg increase in systolic blood pressure was linked to a 17 percent increased incidence of epilepsy.
Mechanisms at work
The association between epilepsy and hypertension could be explained by a number of explanations. The renin-angiotensin system (RAS), which regulates blood pressure, could be one way.
According to studies, rats with repeated seizures had 2.6–8.2 times the components of RAS as mice without seizures. Antihypertensive medications that reduced RAS component levels slowed the onset of seizures and reduced seizure frequency.
More research is needed, however, to determine how much this mechanism explains the link between epilepsy and hypertension, as other research suggests the system may only have a minor impact.
Small vessel disease (SVD), a condition in which the walls of small arteries and capillaries are damaged and consequently do not supply enough oxygen-rich blood to numerous organs, is another likely underlying mechanism, according to the researchers. Scientists discovered that the duration of high blood pressure is a powerful predictor of SVD later in life in a recent study.
SVD has been linked to temporal lobe epilepsy, according to the study. Cortical microinfarcts, minor lesions in cortical tissue, and the disruption of U fibers, which can contribute to excessive excitability and seizures, are all possible explanations. U fibers connect the cerebral cortex’s surrounding sections.
According to the researchers, hypertension is an independent predictor of late-onset epilepsy, with a 2-fold risk of seizures after 45 years.
They do acknowledge, however, that their research has limitations. It is possible that it does not reflect all ethnicities and races because it largely comprised white participants. The researchers also point out that because it is an observational study, it cannot show causation.
Dr. Jason Hauptman, a neurosurgeon at Seattle Children’s Hospital, told Medical News Today, “These results are particularly interesting because whether or not high blood pressure (hypertension) in and of itself is an independent risk factor for stroke has been a topic of controversy,”. “The thought is that independent of the presence of stroke, hypertension may lead to disease of small arteries throughout the brain that can cause injuries on the microscopic level.”
“These injuries could potentially lead to epilepsy with or without the presence of a visible or symptomatic stroke. This research is important because hypertension is not only common, but it is modifiable – that is, we may have ways of assessing and treating it. This would need to be pursued in larger, more diverse patient populations to fully assess exactly how much this is a risk factor and to test the potential interventions,” he stated.
Sanjay Prasad, M.D., a cardiologist at Mayo Clinic Healthcare in London who was not involved in the study, told MNT that the findings were not surprising and that they matched earlier findings.
“This work is observational, so does not confirm that there is a definite direct link. However, it builds on our knowledge base and highlights the importance of lifestyle, regular exercise, and a low salt intake to control blood pressure as an important way of reducing morbidity,” he noted.
“[These results highlight] the need for aggressive control of blood pressure — and encourage everyone —particularly those above the age of 50, to regularly monitor their blood pressure. We also need to assess the impact of blood pressure control in those with epilepsy and after a stroke.”
– Dr. Prasad