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Understanding Memory Loss

Updated on January 10, 2013

Memory loss is often called amnesia. It can be referred as normal forgetting, large-scale loss of memory due to trauma or disease, or selective memory loss related to psychological factors. One of the key concerns of aged people is the experience of memory loss. Occasional lapses in memory are normal in aging adults and understanding the distinction between normal symptoms and warning signs of Alzheimer’s is critical in maintaining cognitive health.

Memory and Limbic system

Modern research confirms the hypothesis that memories are not localized in one particular place in the brain, but rather involve interacting circuits operating across the brain. Thus, although different brain regions perform different memory-related processes, the memories themselves do not appear to reside in any particular place. The limbic system is a group of brain structures that play a key role in memory, emotion, and motivation. It comprises of hippocampus, amygdala, and fornicate gyrus. It is strongly interconnected with the septal area, the hypothalamus, and a medial zone of mesencephalic tegmentum. The hippocampus and surrounding structures are thought to play crucial roles in the encoding and retrieval of memories, whereas amygdala helps to regulate emotions, and thus plays a role in emotional memories.

The hippocampus is thought to be one of the most important brain structures involved in memory. The case of the patient H.M. (only his initials were used to preserve his anonymity), one of the most famous case studies in neuropsychology, strikingly demonstrates the importance of the hippocampus. In 1953, as a 27-year-old man, H.M. underwent brain surgery to control severe epileptic seizures. The surgeons removed his medial temporal lobes, which included most of the hippocampus, the amygdala, and the surrounding structures. Although the operation successfully controlled H.M.’s seizures, it had an altogether unexpected and devastating side effect. Now, he was unable to form new long-term memories in a way that he could later retrieve them. His memory of events prior to the surgery was mostly intact, and his reasoning and thinking skills remained strong. But he could not remember meeting new people or new experiences for more than a few minutes. Researchers concluded that the hippocampus and its surrounding structures in the medial temporal lobe play a critical role in the encoding of episodic memories, especially in binding elements of memories together to locate the memories in particular times and places.

Further evidence for the importance of the hippocampus and other regions of the brain in human memory has been provided by advanced brain imaging techniques, such as positron emission tomography (PET), functional magnetic resonance imaging (fMRI) and neuro-imaging techniques. Brain imaging methods allow researchers to see the activity of the living human brain on a computer screen as a person engages in different types of cognitive tasks, such as reading, solving math problems, or memorizing a list of words. These scanning methods take advantage of the fact that when a brain region becomes active, the rate at which neurons fire increases within this region. Increased neuronal firing in a region causes an increase in blood flow to that region, which the scanners can measure. Therefore, if a person is encoding new information into his memory and the hippocampus is active during encoding, we would expect to see an increased blood flow to the hippocampus. This is exactly the pattern observed in most studies. Neuro-imaging techniques have revealed brain regions, other than hippocampus which are involved in memory. The frontal lobes play an important role in encoding and retrieving memories. For example, certain areas of the left frontal lobe seem especially active during encoding of memories, whereas those in the right frontal lobe are more active during retrieval. An area in the right anterior prefrontal cortex becomes active when a person is trying to retrieve a previously experienced episode. Some evidence indicates that this region may be even more active when the retrieval attempt is successful i.e. when the person not only attempts to remember but is able to remember some previous occurrence too. (Encarta encyclopedia)

Forms of Memory Loss There are two main types of memory loss: Anterograde amnesia and retrograde amnesia.

Anterograde amnesia is a loss of the ability to create new memories after the event that caused the amnesia, leading to a partial or complete inability to recall the recent past, while long-term memories from before the event remain intact. The patho-physiology of anterograde amnesic syndromes varies with the extent of damage and the regions of the brains that were damaged. The most well described regions indicated in this disorder are the medial temporal lobe (MTL), basal forebrain and fornix. When only one side of the MTL is damaged, there is an opportunity for normal functioning or near-normal functioning for memories. Neuroplasticity describes the ability of the cortex to remap when necessary. There was a case, in which the patient underwent two lobectomies. During first surgery, doctors removed a part of her right MTL because of seizures originating from that particular region, and later on the other lobe was also removed because of the development of tumor in that region. This case is unique because it is the only one in which both sides of the MTL were removed at different times. The authors observed that the patient was able to recover some ability to learn when she had only one MTL, but observed the deterioration of function when both sides of the MTL were afflicted. (Di Gennaro G, Grammaldo LG)

Retrograde amnesia (RA) involves the loss of pre-existing memories. With retrograde amnesia it becomes so hard for the patient to remember the past events. A person may be able to memorize new occurrences, but he may be unable to pull memories from the past. This happens when a person is unable to recall their identity. The most commonly affected areas in retrograde amnesia are the hippocampus, the diencephalon and the temporal lobes. There are some aspects essential to the patient that remains unaffected by RA. In many patients, their personality remains the same. Semantic memory, which is general knowledge about the world, is usually unaffected. However, episodic memory, which refers to one's life experiences, is always impaired. (Tulving, E., & Markowitsch, H. J.)

Another form of amnesia is a post traumatic amnesia, which occurs from an external force that causes structural damage to the brain, such as a sharp blow to the head, a diffuse axonal injury, or a childhood brain damage (e.g., shaken baby syndrome). In cases of sudden rapid acceleration, the brain continues moving around in the skull, harming brain tissue as it hits internal protrusions. With post traumatic amnesia, patient is unable to recall information. This type of memory loss can last even after a patient is cured from the event. The brain damage did not affect the person's ability to form new memories. Therefore, the idea that specific sections of retrograde memory are independent of anterograde is supported. Normally, there is a very gradual recovery, however, a dense period of amnesia immediately preceding the trauma usually persists. (Yarnell, P. R., & Lynch, S.)

The effects of memory loss can either be permanent or transient. Even when sufferers regain some of their memory, they may suffer from psychological after effects. These after effects may involve loss of confidence and accurate accountability of the event that was lost. When this occurs, the patient cannot correctly remember past events and they also have a difficult time imagining future events. The cardinals of memory loss are governed by a large assortment of circumstances. So these can cause transient or temporary memory loss, while others can cause permanent amnesia. Additionally, amnesia may also involve the loss of a specific memory or engulf the sufferer’s entire life. An estimated 5.3 million Americans, a little more than 2 percent of the U.S. population, currently live with disabilities from traumatic brain injuries, according to a new report by the Centers for Disease Control and Prevention. The report says that each year, approximately 80,000 Americans experience the onset of disabilities resulting from brain injuries. The data released in the CDC study is considered the most complete picture of the impact of traumatic brain injuries in the United States (CNN, CDC report, April 1999). Following are some of the major causes of memory loss:

Korsakoffs syndrome

Long term alcoholism can lead to Korsakoff’s syndrome, which is basically due to the deficiency of vitamin B1. Alcohol affects the central nervous system and its metabolites can damage the neurons in the brain. With this syndrome, a person might be able to remember things like normal but he might be having difficulty in trying to remember his past events. In addition to amnesia, these patients may also suffer from delirium tremons, confusion and Wernicke’s encephalopathy. (McEntee, W. J., & Mair, R. G.)

Medications

Certain medications can cause memory loss. The most common categories of medicines which are responsible for the lapse in memory are tranquilizers, antidepressants, muscle relaxants and anesthetics. Drugs like antihypertensive drugs, anxiolytics and anti rheumatoid drugs can also cause loss of memory. The effects of memory loss, caused by drugs can be reversed by simply withdrawing from the drugs intake. One of such drugs is Sibutramine (Reductil, Abbott). It is a serotonin and nor-adrenaline reuptake inhibitor and it is widely used in the management of obesity. The Intensive Medicines Monitoring Programme (IMMP) in New Zealand has received a report of amnesia in a 39 year old woman taking sibutramine 10 mg daily. Memory impairment became evident one month after starting sibutramine and progressively worsened until her daily activities were severely affected. She also experienced increased frequency of migraines associated with neck stiffness. Within two weeks of stopping sibutramine her amnesia improved, and it had resolved completely by six weeks. ( David W J Clark, senior research fellow, IMMP)

Sleep Deprivation

Sleep deprivation is another cause for memory loss. When we sleep the brain works in a way to move short-term memory into long-term memory banks. Some experts believe that dreams are appearances of the brain and correctly filing away memories involving the subconscious. If we sleep less than our required hours, our body experiences fatigue and lethargy. Sleep deprivation will interfere with the process of storing information in the memory banks. The fatigue makes it difficult to retrieve our stored memory.

Nutritional Deficiencies

The lack of proteins and healthy fats such as Omega 3 can disrupt the body process to store necessary information in memory banks in the brain. Protein and Omega 3 helps to build new connections and protect established ones. However, there are other factors too that can lead to memory loss within the diet. Lack of vitamin B1 and B12 are specially known for causing memory loss. The lack of vitamin B12 can lead to everlasting brain damage. Vitamin B1 is needed by the neurons as a cofactor for various enzyme activities in the brain. Other vitamins such as vitamin C, vitamin E and vitamin A also plays important role in memory. A 2011 study suggests that increasing Vitamin C and Vitamin E in diets can increase verbal memory functions. Vitamin C is an antioxidant that can protect brain tissues from inflammation and oxidation damage. Foods rich in Vitamin C include broccoli, Brussels sprouts, cabbage, cantaloupe, cauliflower, grapefruit, green and red peppers, kale, kiwi, mango, oranges, papaya, pineapple, strawberries, and tomato juice. Vitamin E can protect brain cell membranes from free radicals. Foods rich in Vitamin E include almonds, canola oil, grape seed oil, hazelnuts, papaya, safflower oil, sunflower seeds, and wheat germ oil. Vitamin E is also prevalent in leafy greens, including arugula, beet greens, collard greens, kale, mustard greens, rapini, spinach, and Swiss chard. (Beck, Leslie)

Stress, Depression and Anxiety Disorders

These disorders affect the concentration power and lowers mental focus in some people. Primarily referred to as psychogenic amnesia or psychogenic fugue, it often occurs due to a traumatic situation that individuals wish to consciously or unconsciously avoid. People experiencing psychogenic amnesia have impaired episodic memory, instances of wandering and traveling, and acceptance of a new identity as a result of inaccessible memories pertaining to their previous identity. (Markowitsch, H. J.)

Aging

Forgetfulness can be a normal part of aging. As people get older, changes occur in all parts of the body, including the brain. As a result, some people may notice that it takes longer to learn new things, they don't remember information as well as they did, or they lose things like their glasses. These usually are signs of mild forgetfulness, not serious memory problems. Advances in medical research, and the growing new field of Geroscience, have enabled us to understand the aging process better, and to live longer. However, despite progress made on the understanding of cellular changes and loss that accompany aging, little progress has been made in treating cognitive problems, most notably the progressive decline in memory function. In most people, age-related memory troubles emerge in mid-life and memory continues to weaken with advancing age. However, memory decline is not an inevitable consequence of aging. An important first step has been the delineation of memory problems associated with normal aging and those associated with diseases such as Alzheimer’s disease. In contrast to neurodegenerative diseases, normal aging is not always associated with the loss of cells. The absence of neural degeneration has directed researchers to consider the possibility that age-related memory deficits may reflect more subtle changes in processes that alter synaptic connectivity, including changes in synaptic plasticity. Several reasons have been speculated as to why older adults use less effective encoding and retrieval strategies as they age. The first is the “disuse” view, which states that memory strategies are used less by older adults as they move further away from the educational system. Second is the “diminished attentional capacity” hypothesis, which means that older people engage less in self-initiated encoding due to reduced attentional capacity. The third reason is the “memory self-efficacy,” which indicates that older people do not have confidence in their own memory performances, leading to poor consequences. It is known that patients with Alzheimer’s disease and patients with semantic dementia both exhibit difficulty in tasks that involve picture naming and category fluency. This is tied to damage to their semantic network, which stores knowledge of meanings and understandings. ( Light, Leah.)

Electroconvulsive Therapy

Electroconvulsive therapy is generally indicated for depression that is resistant to treatment. This involves electrical stimulation of particular parts of the brain through the use of the electrodes. It’s used to induce convulsions to relieve certain psychiatric and psychological disorders. However, memory loss is one of its main side effects. Electroconvulsive therapy can cause either anterograde or retrograde amnesia. As the brain acts in the form of an electrical circuit, electroconvulsive therapy would short circuit the brain and cause major changes in the neuro-chemical communication. The Royal College of Psychiatrists fact sheet states that more than eight out of 10 depressed patients who receive electroconvulsive therapy respond well. Electroconvulsive therapy is the most effective treatment for severe depression and people report that it makes them feel that ‘life is worth living’. The rate of reported persistent memory loss varied between 29% and 55%, but, unlike levels of perceived benefit, the rate did not seem to depend on whether studies were clinical or patient based, with relatively high levels being reported by both types of study. ( Freeman CPL, Weeks D, Kendell RE )

Treatment of memory loss

People with some forgetfulness can use a variety of techniques that may help them stay healthy and maintain their memory and mental skills. Here are some tips that can help: (1) Plan tasks, make "to do" lists, and use memory aids like notes and calendars. Some people find they remember things better if they mentally connect them to other meaningful things, such as a familiar name, song, book, or TV show. (2) Develop interests or hobbies and stay involved in activities that can help both the mind and body. (3) Engage in physical activity and exercise. Several studies have associated exercise (such as walking) with better brain function, although more research is needed to say for sure whether exercise can help to maintain brain function or prevent or delay symptoms of Alzheimer's. (4) Limit alcohol use. Although some studies suggest that moderate alcohol use has health benefits, heavy or binge drinking over time can cause memory loss and permanent brain damage. (5) Find activities, such as exercise or a hobby, to relieve feelings of stress, anxiety, or depression. If these feelings last for a long time, talk with your doctor

New research has identified specific impaired neurons within the human brain that when stimulated, can be recovered. Through studies with fruit flies, it was discovered by Professor Ron Davis that, “once the appropriate neurons are identified in people, in principle at least, one could potentially develop drugs to hit those neurons and rescue those memories affected by the aging process." Research such as this, is bringing us one step closer to developing preventative methods and drugs that can reverse and slow the cognitive declines associated with aging. (Thornhill, Ted.)

Recent research studies upon rats have shown that vaccinations with amyloid-β peptide (AB) can dramatically reduce amyloid deposition in a transgenic mouse model of Alzheimer's disease. ( Dave Morgan1, David M. Diamond)

Conclusion

In today’s World, memory loss is indeed a very disturbing thing for lots of people to deal with. Individuals make conscious and unconscious decisions about if, where, and how to store memories. These influences are manifested in individuals without memory loss and can be usefully applied to help those, with less severe memory loss problems to cope with, work around, or fight their memory loss. No matter what your age is, it's not too late to take steps to prevent memory loss. A good place to start is with the strategies for improving your memory. The lesson for older people is to seek out the company of people who will encourage them to keep on trying. The lesson for children and caregivers is to resist the impulse to jump in and do things for older people that they are capable of doing for themselves

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      Nancy Yager 4 years ago from Hamburg, New York

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      progressivehealth 4 years ago from Boise, Id

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      Jessica 2 years ago

      1) The Beatles line. That LP was playing, Venice, CA, 1969, when I took her back to her place, gave her a rose, and kisesd her against her Murphy bed.2) The play we went to at a high school with our 3 year old daughter, back a ways. I told B today that I remember C's ballet appearance, her chorus shot in the Sondheim thing Out of the Woods, and The Nutcracker auditorium, cold with a bunch of toddlers in tights. I don't remember the high school play.

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      Viny 2 years ago

      1) The Beatles line. That LP was playing, Venice, CA, 1969, when I took her back to her place, gave her a rose, and kiessd her against her Murphy bed.2) The play we went to at a high school with our 3 year old daughter, back a ways. I told B today that I remember C's ballet appearance, her chorus shot in the Sondheim thing Out of the Woods, and The Nutcracker auditorium, cold with a bunch of toddlers in tights. I don't remember the high school play.

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