قد تحدث اضطرابات الذاكرة Memory disorders نتيجة تضرر التراكيب العصبية التشريحية التي تعيق تخزين واستجماع الذكريات. قد تصبح اضطرابات الذاكرة أكثر تقدماً، لتضم سقم ألزايمر، أوقد تكون معتدلة لتتضمن اضطرابات مباشرة عن إصابات الرأس.

قائمة اضطرابات الذاكرة

الإصابة الدماغية المكتسبة (ABI)

العمه

هوعدم القدرة على التعهد على بعض الأمور، الأشخاص أوالأصوات. ينتج العمه نتيجة تضرر المخ (وخاصة الفصوص القذالية والجدارية) أونتيجة الإصابة بالاضطرابات العصبية. يختلف العلاج تبعاً لمسقط وسبب التضرر. يعتمد التعافي على خطورة الاضطراب أوخطورة تضرر المخ. هناك الكثير من الأنوع من التشخيصات الأكثر تخصصاً للعمه، وتضم: ، ، ، ، ، ، ، ، وغيرها.

سقم ألزايمر

سقم ألزايمر هوسقم تنكسي وقاتل يصيب المخ، حيث تُفقد الاتصالات الخلوية بخلايا المخ. يعتبر سقم ألزايمر من أكثر أنواع الخرف شيوعاً. عالمياً، يصاب بسقم ألزايمر حوالي 1-5% من السكان. تقع النساء بشكل غير متناسب ضحايا لسقم ألزايمر، مع وجود أدلة تشير إلى حتى النساء المصابات بسقم ألزايمر يظهرن ضعفاً إدراكياً أكثر حدة مقارنة بالذكور المصابين بالسقم، بالإضافة إلى معدل أسرع من التدهور المعهدي.

• مسح PET لمخ غير مصاب - الصورة مقدمة من مركز الإحالة والتوعية بسقم ألزايمر التابع للمعهد الوطني للشيخوخة بالولايات المتحدة.

• مسح PET لمخ مصاب بسقم ألزايمر - الصورة مقدمة من مركز الإحالة والتوعية بسقم ألزايمر التابع للمعهد الوطني للشيخوخة بالولايات المتحدة.

فقدان الذاكرة

، هي حالة عقلية لا قياسية تتأثر فيها الذاكرة والتفهم بشكل لا يتناسب تماماً مع الوظائف المعهدية الأخرى لدى المريض الذي يبدي انتباهاً واستجابة. هناك نوعين من فقدان الذاكرة: ، والذي يظهر تضرراً في الفص الصدغي الأوسط أوالحـُصيني. يظهر المصابون بفقدان الذاكرة التقدمي صعوبة في التفهم والاحتفاظ بالمعلومات بعد تلف المخ. بشكل عام، يحتفظ المصابون بفقدان الذاكرة الركعي بذكريات حول تجاربهم الشخصية أوفي سياق المعلومات الدلالية المستقلة.

تلف المخ

عادة ما تحدث نتيجة تلف المخ بسبب قوة خارجية، وقد تؤدي إلى حالات فقدان الذاكرة تبعاً لخطورة الإصابة. قد تؤدي إصابات الرأس إلى فقدان مؤقت أومستمر في الذاكرة. في بعض الأحيان قد تحدث حالة بدون فقدان ذاكرة تراجعي، لكن هذاقد يكون أكثر شيوعاً في حالات الآفات المخترقة. يرتبط التلف في المناطق الصدغية الجبهية أوالأمامية بشكل غير متناسب مع فقدان الذاكرة التراجعي. أوضحت الدراسات حتى سقمى فقدان الذاكرة ما بعد الصدمة قد أظهروا فقداناً سريعاً للمعلومات التي تفهموها. من ناحية أخرى، بعد فقدان الذاكرة ما بعد الصدمة، كانت معدلات النسيان طبيعية.

كما لوحظ في القسم المذكور أعلاه عن إصابات المخ الرضية، يمكن حتى تترافق مع ضعف الذاكرة وسقم ألزايمر. ومع ذلك، فيما يتعلق بالشيخوخة، فإنه يشكل تهديدات أخرى كذلك. هناك أدلة تدعم معدل حالات السقوط الكبير بين كبار السن، ويعتبر هذا هوالسبب الرئيسي للوفاة المرتبطة بسقم فقدان الذاكرة ما بعد الصدمة بين الحالات التي تتراوح أعمارهم بين 75 سنة وأكثر. عند النظر للمخطط على يمين الصفحة، يظهر حتى السقوط يشكل فقط 28% من إجمالي مسببات فقدان الذاكرة ما بعد الصدمة، وهذا يعني حتى كبار السن يشكلون نسبة 28% تقريباً من الحالات. وهناك عامل آخر مرتبط بفقدان الذاكرة ما بعد الصدمة والفترة العمرية وهوالعلاقة بين وقت حدوث الإصابة وعمر الحالة في ذلك الوقت. يقدر حتى كبار السن هم الأكثر حاجة للمساعدة في حالات فقدان الذاكرة ما بعد الصدمة.

في بعض الحالات، أفاد بعض الأشخاص بأنهم يتمتعون بذاكرة يقظة بشكل خاص للصور أوالأصوات التي رأوها أوسمعوها قبل الإصابة مباشرة، عند استعادة الوعي، أوخلال الفترة الفاصلة الواضحة بين الإصابة وظهور فقدان الذاكرة ما بعد الصدمة. نتيجة لذلك، ظهر الجدل مؤخراً ما إذا كانت إصابات الرأس وفقدان الذاكرة الشديد تستبعد إمكانية حدوث .

الخرف

يشير إلى 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”. The importance of understanding that the changes most frequently observed and noticed on a daily basis concerning aging loved ones is imperative. While mild cognitive impairment can be considered a normal part of aging, the differences must be noted.

In one study by J. Shagam, it was noted that while Diabetes and Hypertension are not considered part of normal aging, they would be classified under mild cognitive impairment. With this being said, it is important to differentiate the differences with what can be potentially harmful and what is not. It is difficult to accurately diagnose dementia due to the fact that most people are unaware of what to be looking for and also because there is no specific test which can be given as a diagnostic tool.

What is even more evident is that the symptoms among dementia, Alzheimer's and Parkinson's related dementia tend to go beyond just one ailment. While there are different forms of dementia, Vascular dementia as it would sound is associated with vascular cautions.

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. Research has shown that persistent hypertension can be contributory to the breakdown of the BBB. The blood-brain barrier (BBB) serves as a “gatekeeper” for the brain by keeping out water and other substances. Various studies show that as the brain ages the blood-brain barrier starts to break down and become dysfunctional. There are different ways to measure the thinning of the BBB and one that most are familiar with is imaging, this consists of taking pictures of the brain using CT scans, MRI, or PET scans.

Previous research also indicates that with aging and the thinning of the BBB, cognitive changes were also occurring within the section of the brain known as the hippocampus. This shows a relationship between aging and the thinning of the BBB and its effects on the brain. Also indicated by the aging brain are learning and memory impairments.

While changes to the BBB are not a cause of impairment to cognitive functions alone research suggests that there is a relationship. Another impairment which is indicative of brain aging and the breakdown of the BBB is the accretion of iron.

Too much iron in the body can create free radicals which could influence the degeneration of the blood-brain barrier. One other specific age related factor noted in Popsecu et al. is a decrease in estrogen as one ages could adversely affect the breakdown of the blood-brain barrier and create a sensitivity to neurodegeneration. As pointed out earlier, dementia is a broad category of memory impairments most commonly associated with ageing. Another symptom which should be monitored is Type 2 diabetes, which can lead to vascular dementia.

Also linked with vascular dementia issues is high cholesterol; furthermore, this risk factor is related to cognitive decline, stroke, and Alzheimer's disease. It is estimated that within 20 years, worldwide prevalence will increase twofold. By 2050, this number is expected to increase to 115 million. Overall, dementia incidence is similar for men and women. However, after 90 years of age dementia incidence declines in men but not in women.

متلازمة فرط الاستذكار

متلازمة 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.

سقم هنتنگتون

، is an inherited progressive disorder of the brain that leads to uncontrolled movements, emotional instability, and loss of intellectual faculties. 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; sufferers 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 and confinement to a wheelchair or bed.

سقم پاركنسن

، هوسقم neurodegenerative disease. PD and aging share a lot of the same neuropathologic and behavioral features. 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. The most common symptoms include: tremors, slowness, stiffness, impaired balance, rigidity of the muscles, and fatigue. As the disease progresses, non-motor symptoms may also appear, such as depression, difficulty swallowing, sexual problems or cognitive changes.

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. According to studies done in London and in Sicily, 1 in 1000 elderly citizens will be diagnosed with Parkinson's, 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.

الضغط النفسي

It has become clear that aging negatively affects brain function and this can encompass a decrease in locomotor activities and coordination as well as affect in a negative way learning and memory. Certain responses to stress within the hippocampus can have negative effects on learning. In a study done by Mark A. Smith, it is demonstrated that exposure to continuous stress can cause age-related issues to the hippocampus. 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. Also noted within a study relating to age and anxiety and memory it was noted that lesions on the brain can affect spatial learning as well as sex presenting at a disadvantage. Dysfunction within the hippocampus can be a reason behind aging brain changes among the elderly. To sum up anxiety and memory and aging, it is useful to recognize a correlation between what anxiety can cause the body to do and how memories are then formed or not formed, and how the aging brain has enough difficulty on its own trying to perform recall tasks.

متلازمة ڤرنيكى-كورساكوف

is a severe neurological disorder caused by thiamine (vitamin B₁) deficiency, and is usually associated with chronic excessive alcohol consumption. It is characterized clinically by oculomotor abnormalities, cerebellar dysfunction and an altered mental state. Korsakoff's syndrome is also characterized by profound amnesia, disorientation and frequent confabulation (making up or inventing information to compensate for poor memory). 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.

الشيخوخة

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.

The National Health and Nutrition Examination Survey (NHANES) administered the word learning and recall modules from the Consortium to Establish a Registry for Alzheimer’s disease (CERAD) to over three thousand participants 60 years and older in 2011–2014. Trained interviewers administered the test at the end of a face-to-face private interview in an examination center. An extensive analysis of these data has been published. 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 neuritic 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 neuritic 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 neuritic 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 cholinergic hypothesis of geriatric memory dysfunction is an older hypothesis that was considered before beta-amyloid deposits, neurofibrillary tangles, or neuritic plaques. It states that by blocking the cholinergic mechanisms in control subjects you can examine the relationship between cholinergic dysfunction and normal aging and memory disorders because this system when dysfunctional creates memory deficits.

الجوانب الثقافية

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."

انظر أيضاً

• الجهاز العصبي المركزي
• تصوير الأعصاب

المصادر

وصلات خارجية

•  Smith Ely Jelliffe (1920). "Memory and its Disorders". Encyclopedia Americana.