(CNN) -- An estimated 2.3 million adults in the United States have epilepsy, according to the Centers for Disease Control and Prevention. Actress Sky McCole Bartusiak, who passed away Saturday, was one of them.
Bartusiak's mother said her daughter had suffered from epileptic seizures since she was a baby. Epilepsy is a general term for several diagnoses that involve recurring seizures. The seizures are triggered by abnormal electrical activity in the brain that results in involuntary changes in body movement, behavior, sensation and, in some cases, loss of consciousness.
Here are seven things to know about epilepsy:
1. There is no identifiable cause in 50% of cases.
About half of diagnosed epilepsy cases have no known cause, according to the Mayo Clinic. For the cases that are identifiable, epilepsy is the result of:
-- Genetics. It's estimated that up to 500 genes could be associated with epilepsy, according to the National Institute of Neurological Disorders and Stroke, but genes are only part of the cause. Genes also make certain people more sensitive to environmental conditions that can trigger seizures.
-- Head trauma after a traumatic fall or car accident.
-- Brain conditions such a strokes, Alzheimer's disease and tumors. Strokes are the leading cause of epilepsy in adults over age 35.
-- Infectious diseases such as AIDS, viral encephalitis and meningitis.
-- Prenatal injury, such as poor nutrition or oxygen deficiencies. Developmental disorders such as autism or neurofibromatosis can also play a role.
2. Having a seizure does not mean that you have epilepsy.
In order to be considered an epileptic seizure, "the seizure has to be unprovoked and occur two or more times," according to Dr. Lawrence Seiden, a board certified neurologist and psychiatrist at the Peachtree Neurological Clinic.
While it may be difficult to identify between epileptic and nonepileptic seizures, nonepileptic seizures are provoked by a temporary medical condition such as a high fever or low blood sugar levels. In addition, epileptic seizures are caused by an electrical problem in the brain, unlike nonepileptic seizures.
3. Symptoms of epilepsy can vary.
Epilepsy symptoms vary from a blank stare during a seizure to repeated twitching of one's arms and legs, according to the Mayo Clinic. However, even mild seizures can be dangerous especially while driving, swimming or being at another unsafe location at the time of the seizure.
Epilepsy is also associated with other chronic health problems such as depression, obesity, bone loss and reproductive disorders.
4. Up to 18% of people with epilepsy die from SUDEP.
It's known as Sudden Unexplained Death in Epilepsy, according to the Mayo Clinic. The cause of SUDEP is unclear, but doctors have several theories.
Epileptic seizures can cause pauses in breathing, also known as apnea. When these pauses are long enough, oxygen levels in the blood can be reduced to dangerous levels. SUDEP may also be caused by an irregular heart rhythm or cardiac arrest.
5. Epileptic patients don't suffer from mental illness.
One of the common misconceptions about epilepsy, Seiden said, is the belief that epileptic patients are not normal and suffer from mental illness or mental retardation. While people with mental retardation may experience seizures, most epileptic patients have normal or above-average intelligence.
"The majority of people with epilepsy are completely normal except for the few seconds they are having seizures," said Seiden.
6. Medical marijuana may help.
The verdict is still out on medical marijuana among epilepsy experts. Some scientists believe the healing compound in marijuana called cannabidiol, or CBD, has medicinal properties that quiet the excessive electrical and chemical activity in the brain that causes seizures.
While much research is still needed, some children and adults who suffer from severe seizures have responded to medical marijuana when other medications did not work.
Anti-epileptic medications are effective in nearly 50% of the people who are newly diagnosed with epilepsy, according to the Mayo Clinic. When medications are not effective and the exact area of the brain where the seizure is generated is identified, surgery is recommended.
Doctors also recommend a high-fat, low-carb ketogenic diet for children who suffer from epilepsy.
7. People can thrive with epilepsy.
Some of the more famous sufferers (or rumored sufferers) of epilepsy include the philosopher Socrates, French military and political leader Napoleon Bonaparte, Nobel prize founder Alfred Nobel, Russian novelist Fyodor Dostoyevsky, and several Olympic medalists, according to the National Institute of Neurological Disorders and Stroke.