Problems With Long-term & Short-Term Memory

Chronic Medical Conditions

Alzheimer's Disease is the leading cause of dementia, according to the Mayo Clinic. A person's ability to function normally during the day is hindered due to the loss of intellectual and social abilities. The brain tissues continue to worsen, leading to the continuing decrease in memory and mental abilities. 
Creutzfeldt-Jakob disease is a very rare degenerative brain disorder, similar to Alzheimer's disease that deteriorates at a much more rapid pace. 
Parkinson's Disease expands slowly, usually beginning with a tremor in one of the person's hands. In the severe stages of Parkinson's dementia occurs. 
Pick Disease, also known as frontotemporal dementia, is when the frontal and temporal anterior lobes of the brain decrease in size. 
Epilepsy, where a person has unprovoked seizures, may be genetic, or it can be brought on by a severe illnesses that leads to brain damage. 
Wilson's disease is a genetic disorder that may affect a person when he is a child or an adult, causing liver disease and deterioration of the brain. 
Strokes, HIV/AIDS and brain tumors are other chronic conditions that may affect a person's short-term and long-term memory.

Psychological Conditions

Depression, anxiety, addiction to drugs and alcohol are psychological conditions that may lead to memory loss. Depression and anxiety adversely affects a person's ability to sleep, making it hard to concentrate and remember simple things to function normally throughout the day. Alcohol and drug abuse in high volumes may damage the brain permanently, or on a less severe note; cause blackouts--a short period of time that a person is not able to remember.

Trauma

Psychological/emotional disturbances may occur causing a person's brain to have selective memory. Head trauma may lead to different types of memory loss. 
Transient global amnesia: an unusual, brief state of a complete loss of memory. Anterograde amnesia: the inability to remember recent events after a traumatic experience, but the far past is not forgotten. Retrograde amnesia: the ability to remember recent events following a trauma, but not the memories prior to the traumatic event. 
In most cases, memory loss due to a traumatic event is temporary.

Medications

Medications that may cause memory loss, depending on the person, include the anti-inflammatory drug prednisone, heartburn drugs, antianxiety/sedative drugs and insulin, according to Johns Hopkins Medicine. Also, drugs administered to treat cancer, heart disease, high blood pressure, pain, nausea, allergies and colds may be the reason for memory loss. It could be as simple as changing the medications or lowering the dose to restore a person's ability to remember.

Infections

Infections that target the brain, unless treated properly and in a timely fashion, may lead to irreparable damage to parts of the brain causing permanent memory loss. Encephalitis is caused by a viral infection that leads to the development of the inflammation of the brain. In its most severe stages it may cause confusion, mental disturbances and hallucinations. Meningitis is caused by a viral, bacterial or fungal infection that leads to the development of the swelling of membranes (meninges) and cerebrospinal fluid neighboring the brain and spinal cord. 
Normal pressure hydrocephalus is the blockage of fluids in the brain, usually caused by a brain infection. Temporarily, normal pressure hydrocephalus leads to amnesia. Once the pressure of the blockage of the fluids is relieved, recovery is noticed right away, with the person's restoration of memory. The hippocampus, a structure located in the human's brain, significantly affects the ability of a person to accumulate fresh data in their memory, according to Fundamentals of Psychology. However, there are problems with long-term and short-term memory that takes place when the hippocampus or other parts connecting to and from the hippocampus are injured. In some instances the amnesia (memory loss) may be permanent or temporary, affecting either the short-term or long-term memory. Several causes affect a person's memory, not just the progression of age.