It's the stuff movies are made of: After a blow to the head, a person wanders aimlessly, unable to remember who he is or where he came from. While such sudden, profound loss of memory is rare, memory loss is a problem that affects most people, to a degree.
Whether it's occasional forgetfulness or loss of short-term memory that interferes with daily life, there are many causes of memory loss.
Dystonia is a movement disorder in which a person's muscles contract uncontrollably. The contraction causes the affected body part to twist involuntarily, resulting in repetitive movements or abnormal postures. Dystonia can affect one muscle, a muscle group, or the entire body. Dystonia affects about 1% of the population, and women are more prone to it than men.
Alcohol, tobacco, or drug use. Excessive alcohol use has long been recognized as a cause of memory loss.
Smoking harms memory by reducing the amount of oxygen that gets to the brain. Studies have shown that people who smoke find it more difficult to put faces with names than do nonsmokers. Illicit drugs can change chemicals in the brain that can make it hard to recall memories.
Sleep deprivation. Both quantity and quality of sleep are important to memory. Getting too little sleep or waking frequently in the night can lead to fatigue, which interferes with the ability to consolidate and retrieve information.
Depression and stress. Being depressed can make it difficult to pay attention and focus, which can affect memory. Stress and anxiety can also get in the way of concentration. When you are tense and your mind is overstimulated or distracted, your ability to remember can suffer. Stress caused by an emotional trauma can also lead to memory loss.
Nutritional deficiency. Good nutrition -- including high-quality proteins and fats -- is important to proper brain function. Deficiencies in vitamin B1 and B12 specifically can affect memory.
Head injury. A severe hit to the head -- from a fall or automobile accident, for example -- can injure the brain and cause both short- and long-term memory loss. Memory may gradually improve over time.
Stroke. A stroke occurs when the blood supply to the brain is stopped due to the blockage of a blood vessel to the brain or leakage of a vessel into the brain. Strokes often cause short-term memory loss. A person who has had a stroke may have vivid memories of childhood events but be unable to recall what he or she had for lunch.