The National Institutes of Health (NIH) defines long-term memory loss as difficulty remembering events that occurred further in the past. Long-term memories are formed when short-term memories, or non-permanent memories, are consolidated in the hippocampus, a brain structure located in the medial temporal lobe; once the memories are consolidated, they are available independent from the hippocampus in the neocortex, where they can be retrieved. When a patient has long-term memory loss, he has problems recalling stored memories, not creating new memories.
Types of Memories
The Helpguide.org article "Improving Your Memory--Tips and Techniques to Improve Memory," states that long-term memories can be three types of memories: episodic, semantic and procedural. Both episodic and semantic memories are conscious memories, which require active thought to remember; procedural memories, on the other hand, can be recalled unconsciously. Episodic memories are about experiences, semantic memories are factual data and procedural memories are skills and routines.
Long-term memories are stored in the neocortex, part of the cerebral cortex responsible for higher functions in the brain, according to Helpguide.org. The neocortex has separate parts for different functions; for example, there are areas in the neocortex for language, sensation, movement and problem-solving. When part of the neocortex is damaged, the patient will lose the associated memories. For example, if the language area of the neocortex is injured, the patient may have long-term loss of semantic language memories.
Stress is a large factor in long-term memory loss. The Franklin Institute states that during a stressful event, the brain releases the hormone cortisol. In large quantities, such as from long-term stress, cortisol can damage the brain. Cortisol interferes with neurotransmitters, making it difficult for the patient to retrieve long-term memories. This type of long-term memory loss may be temporary, if the patient is able to control her level of stress.
Certain diseases and injuries can cause long-term memory loss by damaging the neocortex; however, these afflictions may cause permanent long-term memory loss. The NIH states that physical injuries, such as head trauma, can affect long-term memory; other possible causes for neocortex lesions are brain tumors and strokes. Substance use, such as as excessive alcoholism, and degenerative diseases, such as Alzheimer's disease, also can result in long-term memory loss.
A patient with long-term memory loss can help reduce the severity of his symptoms by keeping mentally active or doing what Helpguide.org describes as "neurobic" activities. One way to improve recall is to rehearse information, where the patient practices important content repetitively. Using mnemonic devices, which utilize associations to remember items, also can help. The patient can reinforce information by using multiple senses, such as speaking out loud while writing. Increasing the amount of attention used when studying something can help with later recall, as this will strengthen the neural connections.