When a person experiences short-term memory loss, he or she can remember incidents from 20 years ago but is fuzzy on the details of things that happened 20 minutes prior.

There are a number of causes of short-term memory loss, some which are a result of medical conditions and others that are related to injuries or other outside influences. Treatment options depend on what caused the loss, according to the National Institutes of Health (NIH).

A brain aneurysm may cause short-term memory loss, as well as long-term memory loss. Aneurysms are wek, bulging spots on the wall of brain arteries, according to the Brain Aneurysm Foundation (BAF). Brain aneurysms don't always rupture, but when they do, they can cause bleeding into the compartment surrounding the brain. The pool of blood clots, increases tpressure on the brain and can irritate, damage or destroy brain cells. Problem with body functions and mental skills may result. In 30 perecent of brain aneurysm cases, memory problems disappear over time, but recovery may take weeks, according to BAF.

A brain tumor may affect memory. Cancer treatment, head trauma or concussion, brain infections and strokes may also bring about short-term memory loss, according to the NIH. A lack of oxygen to the brain can affect short-term memory. Alcohol and drug abuse, concussions and other trauma to the head can impact short-term memory. Medical conditions such as seizures, epilepsy, heart bypass surgery and depression can also impact short-term memory. One of the first signs of dementia is short-term memory loss.

People who have been victims of or witnessed a traumatic event such as a violent crime or accident can also have their short-term memories affected.

Short-term vs. long-term memory

Short-term memory is the information that a person is currently thinking about or is aware of. It is also called primary or active memory. Recent events and sensory data such as sounds are stored in short-term memory. Short-term memory often encompasses events over a period anywhere from 30 seconds to several days.

Because short-term memories need to be recalled for a lesser amount of time than long-term memories, the ability of the brain to store short-term items is more limited. According to "Memory Loss & the Brain," a newsletter from the Memory Disorders Project at Rutgers University, short-term memory can store anywhere from five to nine items. New information can bump out other items from short-term memory. Long-term memory has much greater capacity and contains things such as facts, personal memories and the name of your third-grade teacher.

Different parts of the brain handle the different stages of memory. Short-term memory primarily takes place in the frontal lobe of the cerebral cortet. Then the information makes a stopover in the hippocampus. A 2014 study published in Proceedings of the National Academy of Sciences found that a small number of neurons in the hippocampus may hold the memories of recent events. Exposure to a particular face becomes linked to these neurons, which fire when the memory is recalled. The memories are then transferred to the areas of the cerebral cortex involved in language and perception for permanent storage.

Amnesia

Amnesia, also called amnestic syndrome, is a loss of memories, such as facts, information and experiences, according to the Mayo Clinic. Unlike a temporary episode of memory loss, amnesia can be permanent. However, though losing one's memory of identity — not knowing who you are — is a common plot device on soap operas and mysteries, amnesia does not usually cause a loss of self-identity. Instead, people with amnesia usually know who they are, but they have trouble with short-term memory; they can't learn new information or form new memories.

Amnesia can occur as a result of head trauma, drug toxicity, stroke, Alzheimer's disease, infection or even emotional shock. This last type is called dissociative amnesia and is classified as psychogenic, or as having a psychiatric origin, and can result in the temporary loss of personal memories and identity.

These memories can often be recovered through psychotherapy, but in cases where amnesia lasts for months or years, the subject may begin an entirely new life. This is called a fugue state, and if those affected didn’t have it hard enough, on recovering their memories of pre-trauma events they usually forget the fugue state!

Tests for short-term memory loss

When testing for any type of memory loss, a doctor will take a medical history and perhaps ask a few questions to test a patient's memory.

Other exams may include cognitive testing to check the patient's mental status and ability to think. The doctor may also order blood tests to check for various conditions including vitamin B-12 deficiency and thyroid disease.

Depending on the results, other tests may include an MRI or CT scan of the head and an EEG to measure electrical activity in the brain. A cerebral angiography may also be ordered to examine blood flow to the brain.

If the cause of the short-term memory is related to a psychological trauma, a therapist or psychologist may be consulted.

Ginkgo biloba

Extracts from the ginkgo tree have been used for centuries in traditional Chinese medicine to treat a variety of ailments, including asthma, bronchitis, and kidney and bladder disorders, according to the NIH. Today, ginkgo extract is used as a dietary supplement for many conditions, including dementia, eye problems, leg pain and tinnitus (ringing in the ears).

However, several studies on the possible health effects have found no conclusive evidence that ginkgo is helpful for any health condition, according to the NIH. A study of more than 3,000 older adults found that ginkgo does not help prevent or slow dementia. There is also no evidence that ginkgo helps with memory enhancement in healthy people.

Improving short-term memory

One of the most common suggestions for a better short-term memory is to use mnemonics. Mnemonics is the technique of attaching a word, phrase or image to an object. One example of a mnemonic is the trick to remember how many days are in a month. “Thirty days hath September, April, June and November …” You can also use the trick to remember things such as a name, such as "Rob wore a red shirt."

Another trick is to have someone put a number of objects out on a table. Give yourself 30 seconds to memorize them. Then take the objects away and try to write down as many as you can in 30 seconds.

Doing activities that engage your brain, such as Sudoku and crossword puzzles, and reading in general can also help improve your memory.

Additional resources

Rutgers: Memory Loss & The BrainNIH: Things Forgotten — Simple Lapse or Serious Problem?NIH: Sleep On It — How Snoozing Strengthens Memories