Memory disorder

Acquired brain injury (ABI) Agnosia Agnosia is the inability to recognize certain objects, persons or sounds. Agnosia is typically caused by damage to the brain (most commonly in the occipital or parietal lobes) or from a neurological disorder. Treatments vary depending on the location and cause of the damage. Recovery is possible depending on the severity of the disorder and the severity of the damage to the brain. Many more specific types of agnosia diagnoses exist, including: associative visual agnosia, astereognosis, auditory agnosia, auditory verbal agnosia, prosopagnosia, simultanagnosia, topographical disorientation, visual agnosia etc. Alzheimer's disease Alzheimer's disease (AD) is a progressive, degenerative and fatal brain disease, in which cell to cell connections in the brain are lost. Alzheimer's disease is the most common form of dementia. Globally approximately 1–5% of the population is affected by Alzheimer's disease. Women are disproportionately affected by Alzheimer's disease. The evidence suggests that women with AD display more severe cognitive impairment relative to age-matched males with AD, as well as a more rapid rate of cognitive decline. File:PET_Normal_brain.jpg|PET scan of a healthy brain - Image courtesy of US National Institute on Aging Alzheimer's Disease Education and Referral Center File:PET_Alzheimer.jpg|PET scan of brain with AD - Image courtesy of US National Institute on Aging Alzheimer's Disease Education and Referral Center Amnesia Amnesia is an abnormal mental state in which memory and learning are affected out of all proportion to other cognitive functions in an otherwise alert and responsive patient. There are two forms of amnesia: Anterograde amnesia and retrograde amnesia, that show hippocampal or medial temporal lobe damage. People with anterograde amnesia show difficulty in the learning and retention of information encountered after brain damage. People with retrograde amnesia generally have memories spared about personal experiences or context independent semantic information. Brain injury Traumatic brain injury (TBI) often occurs from damage to the brain caused by an outside force, and may lead to cases of amnesia depending on the severity of the injury. Head injury can give rise to either transient or persisting amnesia. Occasionally, post-traumatic amnesia (PTA) may exist without any retrograde amnesia (RA), but this is often more common in cases of penetrating lesions. Damage to the frontal or anterior temporal regions have been described to be associated with disproportionate RA. Studies have illustrated that during PTA, head injury patients showed accelerated forgetting of learned information. On the other hand, after PTA, forgetting rates were normal. When looking at the chart to the right on the page, it states that falls are only 28% of the total causes of TBI, so that would suggest that the elderly make up a good portion of that 28% overall. Another factor associated with TBI and age is the relationship between when the injury was sustained and the age at which it occurred. It is estimated that the older the individual, the more likely they would require assistance post TBI. Brain injuries can also be the result of a stroke as the resulting lack of oxygen can cause damage to the location of the cerebrovascular accident (CVA). The effects of a CVA in the left and right hemispheres of the brain include short-term memory impairment, and difficulty acquiring and retaining new information. Dementia Dementia refers to a large class of disorders characterized by the progressive deterioration of thinking ability and memory as the brain becomes damaged. Dementia can be categorized as reversible (e.g. thyroid disease) or irreversible (e.g. Alzheimer's disease). Currently, there are more than 35 million people with dementia worldwide. In the United States alone the number of people affected by dementia is striking at 3.8 million. While studies show that there are “normal” aspects to aging, such as graying hair and changes in vision, there are changes such as forgetting how to do things that are not considered “normal”. This form of dementia is not a slow deterioration but rather a sudden and unexpected change due to heart attack or stroke significantly reducing blood to the brain. Hyperthymestic syndrome Hyperthymestic syndrome causes an individual to have an extremely detailed autobiographical memory. Patients with this condition are able to recall events from every day of their lives (with the exception of memories before age five and days that were uneventful). This condition is very rare with only a few confirmed cases. Because of the inheritability of Huntington's each child born to a parent with Huntington's has a 50% chance of inheriting the disease, leading to a prevalence of almost 1 in 10,000 Canadians (0.01%). The first signs of Huntington's Disease are generally subtle; those affected commonly note tics and twitching as well as unexplained fluctuations of mood. Clumsiness, depression and irritability are noted. What begins as a slurring and slowing of speech eventually leads to difficulty communicating, reliance on a wheelchair, or confinement to a bed. Movement is normally controlled by dopamine; a chemical that carries signals between the nerves in the brain. When cells that normally produce dopamine die off, the symptoms of Parkinson's appear. This degeneration also occurs in normal aging but is a much slower process. Another symptom associated with PD is memory dysfunction. This can be attributed to frontal lobe damage and presents itself in a manner which could be associated in normal aging. However, there is no certain correlation between normal aging and that of Parkinson's disease with relation to memory specifically. although this can vary regionally and affect a large range of age groups. Cognitive impairment is common in PD. Specific parkinsonian symptoms, bradykinesia and rigidity, have been shown to be associated with decline of cognitive function. The underlying neuropathological disturbance in PD involves selective deterioration of subcortical structures, and the executive dysfunction in PD, especially in processes that involve working memory. This has been shown to be related to decreased activation in the basal ganglia and frontal cortex. Elgh, Domellof, Linder, Edstrom, Stenlund, & Forsgren (2009) studied cognitive function in early Parkinson's disease and found that PD patients performed significantly worse than healthy controls in attention, episodic memory, category fluency, psychomotor function, visuospatial function and in several measures of executive function. Patients also exhibited greater difficulty with free recall that required a preserved executive function than with cued recall and recognition in tests of episodic memory. According to a Japanese study, normal elderly subjects had difficulty with memory recognition and the PD elderly subjects had an even more troubling time with recognition than the normal group Another pertinent correlation made by this Japanese survey is that for PD patients their immediate memory response is intact while their ability to recognize memories from the past are inhibited. It is also said that PD patient memory is considered a selective impairment. Certain responses to stress within the hippocampus can have negative effects on learning. What then becomes more noticeable is that the aging brain is not as able to recognize growth, this is a symptom of hippocampal damage. If the information is not being encoded properly in the brain then of course there would not be good memory retention without the consideration of outside implications. However, the consideration of anxiety, memory and overall function must be compromised. An emotional memory is capable of being embedded and then reused in a similar scenario at a later time if need be. A survey published in 1995 indicated that there was no connection to the national average amount of alcohol ingested by a country in correlation to a range of prevalence within 0 and 2.5%. Symptoms of Wernicke–Korsakoff syndrome include confusion, amnesia, and impaired short-term memory. WKS also tends to impair the person's ability to learn new information or tasks. In addition, individuals often appear apathetic and inattentive and some may experience agitation. WKS symptoms may be long-lasting or permanent and its distinction is separate from acute effects of alcohol consumption and from periods of alcohol withdrawal. ==Case studies==

• A.J. (patient) A.J. had a rare memory disorder called hyperthymestic syndrome. She had an inability to forget. Her autobiographical memory was extremely accurate to the point that she remembered every day of her life in detail (with some exceptions). She was unable to control what she remembered or what she forgot. • Clive Wearing Clive Wearing had anterograde amnesia after a rare case of herpes simplex virus I (HSV-I) which targeted and attacked the spinal column and brain. The virus led to a case of encephalitis which caused the brain damage of his hippocampus, resulting in his amnesia. • Henry Molaison, formerly known as patient H.M. Molaison had epileptic seizures and had his medial temporal lobes surgically removed to prevent or decrease the occurrence of the seizures. After the removal of Molaison's medial temporal lobes, he had anterograde amnesia as well as moderate retrograde amnesia. Molaison was still able to retain procedural memory after the surgery. • KC (patient) "The extent of damage to K.C.'s medial temporal lobes, particularly to his hippocampus and parahippocampal gyrus, and associated diencephalic and basal forebrain structures, is in line with his profound impairment on all explicit tests of new learning and memory. There is some uncertainty as to whether this pattern of neurological damage also accounts for his severe remote autobiographical memory loss while sparing his remote spatial memory." ==Aging==

Normal aging, although not responsible for causing memory disorders, is associated with a decline in cognitive and neural systems including memory (long-term and working memory). Many factors such as genetics and neural degeneration have a part in causing memory disorders. In order to diagnose Alzheimer's disease and dementia early, researchers are trying to find biological markers that can predict these diseases in younger adults. One such marker is a beta-amyloid deposit which is a protein that deposits on the brain as we age. Although 20-33% of healthy elderly adults have these deposits, they are increased in elderly with diagnosed Alzheimer's disease and dementia. associated with Alzheimer's disease that increase in number with age Additionally, traumatic brain injury, TBI, is increasingly being linked as a factor in early-onset Alzheimer's disease. Delayed recall scores (median, 25th percentile, 75th percentile) declined with age: 60-69y: 6.4, 4.9, 7.8; 70-79y: 5.5, 3.9, 7.0; 80+y: 4.1, 2.4, 5.8. One study examined dementia severity in elderly schizophrenic patients diagnosed with Alzheimer's disease and dementia versus elderly schizophrenic patients without any neurodegenerative disorders. In most cases, if schizophrenia is diagnosed, Alzheimer's disease or some form of dementia in varying levels of severity is also diagnosed. It was found that increased hippocampal neurofibrillary tangles and higher amyloid plaque density (in the superior temporal gyrus, orbitofrontal gyrus, and the inferior parietal cortex) were associated with increased severity of dementia. Along with these biological factors, when the patient also had the apolipoprotein E (ApoE4) allele (a known genetic risk factor for Alzheimer's disease), the amyloid plaques increased although the hippocampal neurofibrillary tangles did not. It showed an increased genetic susceptibility to more severe dementia with Alzheimer's disease than without the genetic marker. As seen in the examples above, although memory does degenerate with age, it is not always classified as a memory disorder. The difference in memory between normal aging and a memory disorder is the amount of beta-amyloid deposits, hippocampal neurofibrillary tangles, or amyloid plaques in the cortex. If there is an increased amount, memory connections become blocked, memory functions decrease much more than what is normal for that age and a memory disorder is diagnosed. ==Cultural perspectives==

The pervasiveness of mental health illnesses can be illustrated by looking at the size of the Diagnostic and Statistical Manual IV-TR (DSM IV-TR). Epidemiological studies have shown an increase in mental health cases globally. In 2050, there could be a pandemic of neurological diseases. An aging baby-boom population increases the demand for mental health care. Western culture's gauge of mental illness is determinate on level of dangerousness, competence, and responsibility. This has led to many individuals being denied jobs, less likely to be able to rent apartments, and more likely to have false criminal charges pressed against them. The level of services available to an ever aging and memory-impaired demographic will need to increase in spite of the stigma against mental illness. With such a stigmatization of memory disorders, and mental illnesses in general, it can be especially hard for those providing aid for these individuals. Some individuals “are unable to acquire or retain new information, making it difficult or impossible to meet social, family and work-related obligations.” Because of this, there is a large responsibility placed on caregivers (usually children) to uphold economic and emotional upkeeps. While there are services available for this group, very few make use of them. In Asian collectivist cultures, focus lies on the social interactions between members of society. Every individual in the society has a certain role to fulfill, and it is deemed socially acceptable to uphold these roles. Furthermore, there is a focus on a balance of body, mind, and spirit. As a result, there is a large discrepancy between what should be deemed acceptable treatments for memory disorders that focus on interpersonal relationships and adjustments to others' expectations rather than a Western-led treatment schedule.. In these Asian cultures, mental illness is believed to be the result of an imbalance of hot-cold/wet-dry which interferes with the proper functioning of the nerves, heart, liver, lungs, kidneys, and spleen. Such an imbalance can sometimes been seen as a point of beauty as "one is the recipient of others' concern and sympathy." ==In popular culture==

Characters with memory disorders have helped to move literature and media along by allowing for suspense to be created either through retrograde or traumatic amnesia as seen in Alfred Hitchcock's Spellbound. It can also provide comic relief if a character is introduced who has short-term memory impairments. Some examples from film and television that depict characters with memory disorders include: • Denny Crane, a character from the television show Boston Legal, shows cognitive impairment that could be indicative to Alzheimer's disease. • Dr. Philip Brainard, a character in the movie The Absent-Minded Professor, displays mild memory impairment. • The character Dory, from the movie Finding Nemo, shows severe short-term memory loss. • Actor Michael J. Fox was diagnosed with Parkinson's disease in 1991, which caused memory loss over time. • In the film Memento, the main character, Leonard Shelby, has a short-term memory condition (anterograde amnesia) in which he cannot form new memories. • The character Savant, a member of the DC Comics superhero team the Birds of Prey, exhibits both photographic and non-linear memory as a result of what is described only as "a chemical imbalance". • Iris Murdoch, the British writer and philosopher, developed Alzheimer's disease. She was portrayed by Kate Winslet in the film Iris in 2001. • In The Notebook (2004), the film based on the novel by Nicholas Sparks (1996), the character Allie Hamilton (played by Rachel McAdams) developed Alzheimer's disease. • In the video game Firewatch, the main character's wife is diagnosed with early-onset Alzheimer's disease at the beginning of the game. • In the Peter Pan stories by J. M. Barrie, Peter is very immature and lacks the capacity to form mental representations. Because of this he is amnesic. He is unable to form episodic memories though he has acquired certain skills such as steering a boat. He knows certain facts including facts about himself but does not how he comes to know these facts. He has difficulty recognising people but knows that they are familiar to him. He has some memory of emotions and desires. • Remy "Thirteen" Hadley from House starts showing early signs of Huntington's disease and takes the test for it in the fourth season finale. ==See also==