Memory loss is a common symptom of many neurological conditions. Although the exact mechanics of memory are not completely understood, anything that disrupts functioning of the brain has the ability to result in memory loss. Memory loss may be temporary or permanent, depending on the cause and the extent of damage (if any) to the brain.

Memory is usually described as being short-term or long-term. Short-term memory is the ability to store or recall information for a short period of time (e.g., a couple of minutes or hours). Long-term memory is the ability to store or recall information for indefinite periods of time.

Memory loss does not necessarily indicate a loss of intelligence or inability to make judgments. However, certain conditions that can cause memory loss may also cause cognitive disorders such as the loss of speech or inability to understand speech (aphasia), the loss of movement (apraxia) or the loss of the ability to recognize familiar people, places, objects or sensations such as smells (agnosia).

The term amnesia is sometimes used interchangeably with memory loss. There are two major types of memory loss that involve disease or injury to the brain. These are:

• Anterograde amnesia. The inability to form new long-term memories after a certain point in time (e.g., after a head injury).
  
  
• Retrograde memory loss. The loss of some or all long-term memories before a certain point in time (e.g., prior to a head injury).

Another, less common type of memory loss is called psychogenic memory loss. This involves a loss of memory, either short- or long-term, that is the result of emotional trauma. It is not related to physical damage to the brain.

Memory loss can be caused by many conditions, including:

• Alzheimer's disease
• Head injury
• Epilepsy
• Parkinson’s disease
• Alcohol or drug abuse
• Stroke
• Tumors or brain lesions
• The use of certain medications
• Psychological trauma

Some instances of memory loss resolve without treatment. Memory loss that is caused by damage to the brain may be permanent and, although some medications are available to slow the progression of memory loss, there is rarely a cure. In some cases, treating the underlying disease or condition may resolve memory loss.

Many neurological conditions are poorly understood and no known prevention methods exist for these causes of memory loss. However, some causes of memory loss (e.g., head injury, substance abuse) may be prevented with appropriate self-care or avoidance techniques.