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.
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 impacted.
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, the brain can store anywhere from five to nine items. Long-term memory has much greater capacity and contains things such as fact, personal memories and the name of your third-grade teacher.
The different stages of memory are handled by different parts of the brain. Short-term memory is primarily takes place in the frontal lobe ofthe cerebral context. Then the information makes a stopover in the hippocampus and is then transferred to the areas of the cerebral cortex involved in language and perception for permanent storage.
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.
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 od a mnemonic is the trick many people learned in school 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 reporting by contributor Ben Mauk.