What are common causes of short term memory loss?

Chronic and acquired: Neurologists would include alzheimer's disease, head injury, the effect of alcohol abuse and thiamine deficiency, and pernicious anemia, as either irreversible or relatively reversible causes. However, difficulty with memory is not uncommon during periods of severe stress, ongoing sleep deprivation, such as sleep apnea, and reactions to many common medicines which possess anticholinergic effects.

Several: Intoxication, aging, alzheimer's, thiamine deficiency, stroke, brain radiation, electroconvulsive therapy, medication side effects, seizures, encephalitis, traumatic brain injury, hypoxia, cardiac arrest etc.