Sudden short-term memory loss is often as frightening for loved ones as it is for the sufferer. The fact that it comes on suddenly yields clues to its possible causes. New cases of confusion or sudden memory loss for no apparent reason should be evaluated by a medical professional immediately.
Stroke is one of the most serious reasons for sudden short-term memory loss. The National Stroke Association explains that a stroke, also called a cerebrovascular accident, can impair the memory in several different ways. It may be difficult for the individual to learn new things or it may be difficult to recall what he has learned since the stroke.
A blow to the head can sometimes result in memory loss that is short-term and sudden. This can happen even when concussion is not sustained. Being in the vicinity of a bomb exploding, for example, or being in a serious car accident can damage the brain in this way.
Several psychiatric disorders can cause short-term memory loss. People with dissociative fugue, dissociative identity disorder and certain types of amnesia can all have symptoms congruent to this diagnosis.
Short-term memory loss may be caused by a lack of oxygen to the brain. This could come from being choked, smothered or nearly drowned. Severe respiratory problems can also lead to low blood oxygen, which leads to oxygen deprivation in the brain.
Several types of infection can lead to sudden memory loss. The U.S. National Library of Medicine lists Lyme disease as one potential culprit. Another is called tertiary syphilis, a condition that may occur decades after syphilis is contracted but left untreated. Tuberculosis and AIDS may also cause significant memory loss.
A brain tumor is sometimes found to be responsible for sudden short-term memory loss. It may be malignant or benign, and fast- or slow-growing, yet have the same outcome.
Severe Psychological Stress
A severe stress that pushes a person beyond his coping abilities may cause memory problems and other mental disturbances. This often happens in serious illness and traumatic situations such as being kidnapped or upon witnessing violent acts. Extreme sleep deprivation is another possible cause.
According to the U.S. Food and Drug Administration, many types of drugs may be responsible for memory loss. These include antidepressants, antipsychotics, sleeping pills and pain medications, among others. General anesthesia is also notorious for affecting memory, particularly in elderly patients. Alcohol and illegal drugs can greatly impair memory and other cognitive abilities.