Нарушения памяти и агнозия: причины, виды и лечение.

Memory disorders are the result of damage to neuroanatomical structures that hinders the storage, retention and recollection of memories. Memory disorders can be progressive, including Alzheimer's disease, or they can be immediate including disorders resulting from head injury.

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 (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.

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.

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 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.

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. 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.

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."