What causes seizures in adults
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Last updated: April 4, 2026
Key Facts
- Epilepsy is the most common cause of recurrent seizures, affecting over 65 million people worldwide.
- Stroke is a leading cause of new-onset seizures in older adults, accounting for approximately 10-20% of cases.
- Traumatic brain injuries (TBIs) can lead to post-traumatic epilepsy in up to 20% of severe injury cases.
- Brain tumors are responsible for about 3-5% of adult seizure cases.
- Metabolic disturbances like low blood sugar (hypoglycemia) or electrolyte imbalances can trigger seizures.
What Causes Seizures in Adults?
Seizures are sudden surges of electrical activity in the brain that can cause changes in behavior, movements, feelings, and consciousness. While often associated with epilepsy, seizures in adults can arise from a wide range of underlying causes. Understanding these causes is crucial for diagnosis, treatment, and managing the condition effectively.
Epilepsy: The Primary Culprit
Epilepsy is a neurological disorder characterized by recurrent, unprovoked seizures. It is the most common cause of seizures in adults. In many cases of epilepsy, the exact cause is not identified (idiopathic epilepsy), but it is believed to involve genetic predispositions and brain abnormalities. However, epilepsy can also be caused by:
- Genetic factors: Certain genes can make individuals more susceptible to seizures.
- Brain damage from injury: Head trauma, such as from accidents or falls, can lead to scarring in the brain that disrupts normal electrical activity.
- Brain infections: Conditions like meningitis or encephalitis can inflame the brain and trigger seizures.
- Stroke: A stroke, which occurs when blood supply to part of the brain is interrupted, is a significant cause of seizures, especially in older adults. The damaged brain tissue can become a source of abnormal electrical discharges.
- Brain tumors: Tumors, whether cancerous or benign, can press on brain tissue or disrupt its function, leading to seizures.
- Congenital disorders: Abnormalities in brain development before birth can increase the risk of seizures later in life.
Other Medical Conditions and Triggers
Beyond epilepsy, numerous other medical conditions and external factors can provoke seizures in adults:
- Traumatic Brain Injury (TBI): Moderate to severe TBIs can cause damage to brain tissue, increasing the likelihood of seizures, sometimes years after the initial injury.
- Central Nervous System (CNS) Infections: Infections like meningitis, encephalitis, and brain abscesses can cause inflammation and irritation in the brain, leading to seizures.
- Brain Tumors: Both primary brain tumors (originating in the brain) and metastatic tumors (spreading from elsewhere in the body) can cause seizures by disrupting brain function.
- Stroke: As mentioned, stroke is a common cause, particularly ischemic strokes (due to blocked blood flow) and hemorrhagic strokes (due to bleeding in the brain).
- Degenerative Brain Diseases: Conditions like Alzheimer's disease and other forms of dementia can sometimes be associated with seizures.
- Metabolic Disorders: Significant imbalances in body chemistry can trigger seizures. These include:
- Low blood sugar (hypoglycemia)
- High blood sugar (hyperglycemia)
- Electrolyte imbalances (e.g., low sodium, calcium, or magnesium)
- Kidney or liver failure
- Fever (less common in adults than children, but possible with severe infections)
- Autoimmune Diseases: Certain autoimmune conditions where the body attacks its own brain tissue (e.g., anti-NMDA receptor encephalitis) can cause seizures.
- Medications and Substances: Some prescription drugs, over-the-counter medications, and illicit drugs can lower the seizure threshold. Withdrawal from certain substances (like alcohol or sedatives) can also trigger seizures.
- Certain Illnesses: Severe infections elsewhere in the body can sometimes lead to febrile seizures, though this is more common in children.
When to Seek Medical Attention
If you experience a seizure for the first time, or if your seizure patterns change, it is essential to seek immediate medical attention. A thorough medical evaluation, including a neurological examination, EEG (electroencephalogram), and possibly brain imaging (MRI or CT scan), is necessary to identify the underlying cause. Prompt diagnosis and appropriate treatment can help manage seizures effectively and improve quality of life.
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