Top Causes of Amnesia
What is amnesia?
Amnesia is when you can’t form new memories or recall experiences or old memories. Amnesia usually happens suddenly and has a clear cause. Other types of memory loss, like dementia, often develop more gradually.
Amnesia can be temporary or permanent and you may have partial or total memory loss. Some people with amnesia have trouble remembering the past, called retrograde amnesia. Others can't form new memories, called anterograde amnesia.
TV shows and movies typically depict dramatic cases of complete amnesia, usually after a car accident or some other trauma. In most instances, amnesia is not as severe as depicted. And in cases of trauma, it doesn’t just suddenly correct one day but is a more gradual process. —Dr. Karen Hoerst
Dissociative amnesia is usually a response to a particular stressor. Amnesia can also happen after a brain injury, seizures, or even severe stress.
While there can be some overlap with dementia, amnesia typically leads to more profound memory loss. This includes symptoms like not recognizing people you know or remembering events or information. Dementia is progressive, meaning that it worsens with time, while amnesia may remain the same or even improve with time.
Since amnesia happens suddenly, you should see a doctor to check for any serious medical issues. People with amnesia may not be aware of their own symptoms and may need others to help identify it.
How long does amnesia last?
Amnesia can be short-lived, lasting under 24 hours, or it can be long-term, depending on the cause. Amnesia caused by temporary loss of blood flow, limited epileptic seizures, and psychological events tend to be temporary.
Permanent injury to the brain, like with a traumatic brain injury, tends to cause long-lasting or permanent amnesia.
Can amnesia be reversed?
Yes, amnesia can go away in many cases, depending on the reason behind it. Often, your memory will return spontaneously following a mild concussion or drug-induced memory loss. Other common causes of reversible memory loss include seizures, migraines, and viral encephalitis. But memory loss from dementia is not usually reversible.
The most important thing to tell your doctor is if you are having any other symptoms, particularly neurological symptoms like headache, weakness, slurred speech, fevers. —Dr. Hoerst
1. Traumatic brain injury
Traumatic brain injury (TBI) can happen when you get bumped, jolted, or take a blow to the head. The injury damages the brain. According to the American Academy of Neurological Surgeons, TBI is most common in adults over age 75, very young kids, and young adults, ages 15 to 24. Concussion is a mild form of TBI.
Because you may not remember what happened right before or after the injury, your doctor might need to hear what happened from someone who saw the injury. You may need imaging tests, such as a CT (computed tomography) or MRI (magnetic resonance imaging) scan.
Treating traumatic brain injury
Your treatment is based on how severe the injury is. If you have a concussion, you may need rest and therapy. Your amnesia will probably improve with these measures.
You may need medications for headaches, such as amitriptyline. If you have a severe case of TBI, you may need medications and treatments to manage seizures, bleeding in the brain, or surgery.
2. Transient global amnesia (TGA)
- Sudden inability to remember new information
- Repeatedly asking the same questions
Transient global amnesia (TGA) is when someone is suddenly unable to form new memories. Previous memories are preserved.
With TGA, you may not recognize you have amnesia at first. But those around you notice that you are repeating questions about events that happened. TGA occurs in adults ages 50 to 80 and typically lasts less than 24 hours.
No one knows for sure what causes TGA. It could be caused by a blood flow disorder, seizure disorder, migraine, or stress.
Your doctor will do an MRI scan and electroencephalogram (EEG), which looks at the brain’s electrical activity. These tests will rule out a stroke or seizure.
There isn’t a specific treatment for TGA, but your doctor should assess your stroke risk.
- Shaking of the whole body or part of the body
- Tongue bite
- Not remembering a seizure
A seizure is a sudden, abnormal release of electrical signals in the brain. Normally these signals pass from one cell to another in a coordinated way, but during a seizure there is no pattern.
It’s common to not remember having a seizure or the time right before or after it. People with prior injuries to the brain, strokes, and a family history of seizures have a higher risk for seizure.
Treating a seizure
If you are diagnosed with a seizure, you will be given an anti-seizure medication, such as levetiracetam.
Some people will note that they “don’t like to talk about their past,” but in some instances it is because they have actually blocked out part of this memory. After a detailed history, often the cause of the amnesia can be determined, but in other cases, pictures of the brain—particularly with MRI as well as labs—are needed. —Dr. Hoerst
4. Wernicke-Korsakoff syndrome (WKS)
- Confusion and amnesia
- Flickering eye movements
- Inability to move eyes in certain directions
- Jerky, unsteady, or uncoordinated walk
- Feeling confused and not making sense while talking
Wernicke-Korsakoff syndrome (WKS) is caused by a deficiency of thiamine, also called vitamin B1. This condition is a spectrum, ranging from the acute stage, called Wernicke's encephalopathy, to the chronic stage, called Korsakoff syndrome.
In Wernicke’s encephalopathy, people can experience confusion, difficulty walking, and jerking eye movements. Korsakoff syndrome can cause confabulation, which is when people create false memories and are convinced that the information is true.
WKS is more likely to occur in people with alcoholism. But others with nutritional deficiencies may be at risk, including people who have a poor diet or don’t have access to enough food, those who have had weight-loss surgery, and those with serious illnesses, such as cancer or AIDS.
Wernicke’s encephalopathy can be life-threatening and is a medical emergency. Go to the ER or call 9-1-1. People with WKS can also experience alcohol withdrawal, which can be life-threatening.
Doctors will give you thiamine through an IV line, prescribe thiamine supplements, and treat other symptoms such as agitation or withdrawal with benzodiazepine medications.
If gait difficulty is a problem, physical therapy may also be needed. Early treatment offers the best chance for recovery from WKS.
5. Viral encephalitis
Encephalitis is irritation and swelling (inflammation) of the brain. The most dangerous type of encephalitis is caused by a viral infection, often the herpes simplex virus. Other viruses, such as West Nile virus, which is transmitted through a mosquito bite, can also cause encephalitis.
Viruses can damage a part of the brain, called the temporal lobe, responsible for memory. For that reason, there is a high risk of memory loss and seizures.
People with viral encephalitis normally develop symptoms very quickly and can go from feeling normal to being critically ill in a matter of days. Your doctor will look for symptoms like severe headache and fever. You may need imaging tests, such as MRI and lumbar puncture (spinal tap).
Viral encephalitis is treated with antiviral medications like acyclovir given through an IV line. But even with treatment, the risk of death can be up to 20%, according to the Encephalitis Society. Starting antiviral therapy early improves your chance for recovery.
Dementia slowly destroys memory and the ability to think and remember clearly. There are different types of dementia, like Alzheimer’s disease and frontotemporal dementia. Unlike other types of amnesia, the memory loss of dementia is progressive. Dementia also leads to problems performing tasks, such as self care, and neurological symptoms like difficulty speaking and walking.
Treatment is complicated and focuses on helping people maintain their mental function, manage behavioral symptoms, and slow the progress of the disease.
Other possible causes
Other conditions that may cause amnesia include:
When to call the doctor
Call your primary care doctor if you have any of these signs:
- Amnesia after a head injury
- Severe confusion or feeling disoriented
- You are unable to recognize close friends and family members.
- You are unable to identify yourself.
- You are unaware of the current date or events.
Should I go to the ER?
You should go to the emergency department if:
- You have sudden loss of memory, sudden confusion, or feel disoriented.
- You have neurological symptoms like weakness in an arm or leg, slurred speech, or shaking of a part of your body or your whole body.
- You have memory loss or confusion after a head injury and are taking a blood thinner like aspirin or coumadin.
Depending on the underlying causes, treatment that may help memory include:
- Meditation. This calming practice can help the nervous system function properly.
- A regular sleep schedule. Go to bed at the same time and wake up at the same time every day, and get 8 hours of sleep each night.
Other treatment options
- Medications for seizures
- Occupational therapy. This helps people learn new things and adjust to a new lifestyle when amnesia is long-lasting.
Dr. Hoerst is a board-certified Neurologist. She received her undergraduate degree in Neuroscience from the University of Scranton in 2005 and Jefferson Medical College (now Sidney Kimmel Medical College) in 2009. She completed an internal medicine internship, neurology residency and vascular neurology fellowship at Thomas Jefferson University Hospital in Philadelphia (2014). After completing her training, Dr. Hoerst joined Reading Hospital in West Reading, Pennsylvania where she acted as the Stroke Program Medical Director in addition to providing emergency, inpatient, and outpatient care. In 2019, she transitioned to the role of teleneurologist at SOCTelemed, providing emergency and inpatient care via teleneurology to patients with neurological disease across the country.
She also serves as a physician clinical reviewer for Magellan Health. Dr. Hoerst joined Buoy Health in 2021. She believes that providing accessible, accurate medical knowledge allows people to make informed and empowered decisions about their health.