Is There a Link Between Hypertension and Epilepsy?

Stroke is the most common cause of epilepsy in older age. Subclinical cerebrovascular disease is believed to underlie some of the 30-50% of late-onset epilepsy without a known cause. Epilepsy is the third most common neurological condition that affects older people after stroke and dementia. 

Research shows that late-onset epilepsy has become more widespread in the last 2 decades, with the number of people with the condition continuing to rise as the aging population increases. 

Understanding the role of vascular risk factors in late-onset epilepsy could help policymakers design public health measures and preventive strategies to curb and manage rates of the condition.

New Research Study 

A new study led by the Boston University School of Medicine in the United States and published in the journal Epilepsia, investigated the link between vascular risk factors and the onset of epilepsy. The researchers found that hypertension had links to an almost 2-fold higher risk of developing late-onset epilepsy. This risk was even higher for those who did not use medication to regulate their blood pressure. 

The study used data from the Framingham Heart Study (FHS), an ongoing, community based study that began in 1948. Its Offspring Cohort tracks the health outcomes of 5,124 of the original participants’ children from health examinations every 4 years. 

In total they used data from 2,986 people who attended their fifth examination between 1991 and 1995, were at least 45 years old and whose health records contained data on vascular risk factors (systolic and diastolic blood pressure of 140 mm Hg and above, and diastolic of 90 mm Hg and above; as well as the use of antihypertensive medications). 

To screen participants for epilepsy or seizure, the researchers used routine chart reviews for neurological conditions, self-reported seizures, International Classification of Diseases Ninth Revision (ICD-9) codes linked to epilepsy or seizures, and antiepileptic drug use. The researchers also used brain imaging and electroencephalography (EEG), cardiac and other relevant data to ascertain cases of epilepsy.

They found 55 examples of epilepsy of which 26 were definite, 15 probable and 14 suspected. 

The researchers found that hypertension had links to an almost 2-fold higher risk of epilepsy. However, the other risk factors had no links to epilepsy. They also found that every 10 mm Hg change in systolic blood pressure was associated with a 17% higher risk of developing epilepsy.

Several theories may explain the link between epilepsy and hypertension. One mechanism may be via the renin-angiotensin system (RAS), which regulates blood pressure.

Research suggests that after repetitive seizures, rats have 2.6–8.2 times the components of RAS than mice without seizures. Antihypertensive drugs that lowered levels of RAS components delayed seizure onset and reduced seizure frequency.

According to the researchers, another possible underlying mechanism is small vessel disease (SVD), a condition in which the walls of small arteries and capillaries are damaged and thus do not deliver sufficient oxygen-rich blood to various organs. In a recent study, scientists found that the duration of high blood pressure is a strong predictor of SVD in later life.

The researchers conclude that hypertension is an independent predictor of late-onset epilepsy and carries a 2-fold risk of developing seizures after 45 years.

Source: 

Annie Lennon. (2021, Nov 23). Hypertension linked to 2.5 times higher risk of epilepsy. Medical News Today. Retrieved from: 

https://www.medicalnewstoday.com/articles/hypertension-linked-to-2-5-times-higher-risk-of-epilepsy

Image from: 

https://utswmed.org/conditions-treatments/epilepsy/