Memory disorder
Encyclopedia
Memory
can be defined as an organism's ability to encode
, retain, and recall
information. Disorders of memory can range from mild to severe, yet are all a result of damage to neuroanatomical structures; either in part or in full. This damage 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
.
is the inability to recognize certain objects, persons or sounds, yet there are many more specific diagnoses of agnosia. 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.
Some examples of specific types of Agnosia include: Visual Agnosia, Auditory Agnosia, Prosopagnosia
, Somatosensory agnosia, Simultanagnosia, Apraxia
, Associative Agnosia
, etc.
(AD) is a progressive, degenerative and fatal brain disease, in which cell to cell connections in the brain are lost. As a result, the death of brain cells occur, therefore giving Alzheimer's disease the title as the most common form of dementia. In the entire world, approximately 1-5% of the population is affected by Alzheimer's disease. It is estimated that 500,000 Canadians currently suffer from Alzheimer’s disease or a related dementia. It is the most significant cause of disability among individuals aged 65 and above. Women are disproportionately the victims of Alzheimer’s disease, with evidence suggesting 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.
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. Anterograde amnesics show difficulty in the learning and retention of information encountered after brain damage. Retrograde Amnesics generally have memories spared about personal experiences or context independent semantic information.
often occurs from damages 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.
In some cases, individuals have reported having a particularly vivid memory for images or sounds occurring immediately before the injury, on regaining consciousness, or during a lucid interval between the injury and the onset of PTA. As a result, recent controversy has emerged about whether severe head injury and amnesia exclude the possibility of post-traumatic stress disorder
(PTSD) symptoms. In a study carried out by McMillan (1996), patients reported ‘windows’ of experience, in which emotional disturbance was sufficient to cause PTSD. These 'windows' involved recall of events close to impact (when RA was brief), of distressing events soon after the accident (when PTA was short), or of 'islands' of memory (e.g. hearing the screaming of others).
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.
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. 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.
. Patients with this disorder 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 disorder is very rare with only a few confirmed cases.
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 Huntinton'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; suffers 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.
(PD) is a neurodegenerative disease. 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. 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.
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.
(WKS) 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 affects of alcohol consumption and from periods of alcohol withdrawal.
A.J. suffered from 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 suffered from 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.
HM (patient)
H.M. suffered from epileptic seizures and had his medial temporal lobes surgical removed to prevent or decrease the occurrence of the seizures. After the removal of H.M.'s medial temporal lobes, he suffered from anterograde amnesia as well as moderate retrograde amnesia. H.M. 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
."
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.
_presenile_onset.jpg)
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.
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 While prejudiced views may have started out with a kernel of truth, the level of services available to an ever aging and memory-impaired demographic will need to increase as well.
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.
One is deemed to be mentally ill if there is an imbalance of hot-cold/wet-dry, and the proper functioning of the nerves, heart, liver, lungs, kidneys, and spleen. In an event of an imbalance, it can sometimes been seen as a point of beauty as "one is the recipient of others' concern and sympathy."
’s Spellbound
. It can also provide comic relief if one introduces a character who has short-term memory impairments.
Some examples from movies and television shows that often depict characters suffering from memory disorders include:
Memory
In psychology, memory is an organism's ability to store, retain, and recall information and experiences. Traditional studies of memory began in the fields of philosophy, including techniques of artificially enhancing memory....
can be defined as an organism's ability to encode
Encoding (Memory)
Memory has the ability to encode, store and recall information. Memories give an organism the capability to learn and adapt from previous experiences as well as build relationships. Encoding allows the perceived item of use or interest to be converted into a construct that can be stored within the...
, retain, and recall
Recall (memory)
Recall in memory refers to the retrieval of events or information from the past. Along with encoding and storage, it is one of the three core processes of memory. There are three main types of recall: free recall, cued recall and serial recall...
information. Disorders of memory can range from mild to severe, yet are all a result of damage to neuroanatomical structures; either in part or in full. This damage hinders the storage, retention and recollection of memories. Memory disorders can be progressive, including Alzheimer's disease
Alzheimer's disease
Alzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death...
, or they can be immediate including disorders resulting from head injury
Head injury
Head injury refers to trauma of the head. This may or may not include injury to the brain. However, the terms traumatic brain injury and head injury are often used interchangeably in medical literature....
.
Agnosia
AgnosiaAgnosia
Agnosia is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss...
is the inability to recognize certain objects, persons or sounds, yet there are many more specific diagnoses of agnosia. 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.
Some examples of specific types of Agnosia include: Visual Agnosia, Auditory Agnosia, Prosopagnosia
Prosopagnosia
Prosopagnosia is a disorder of face perception where the ability to recognize faces is impaired, while the ability to recognize other objects may be relatively intact...
, Somatosensory agnosia, Simultanagnosia, Apraxia
Apraxia
Apraxia is a disorder caused by damage to specific areas of the cerebrum. Apraxia is characterized by loss of the ability to execute or carry out learned purposeful movements, despite having the desire and the physical ability to perform the movements...
, Associative Agnosia
Associative agnosia
People with associative agnosia fail in assigning meaning to an object, animal or building that they can see clearly. Most cases have injury to the occipital and temporal lobes and the critical site of injury appears to be in the left occipital-temporal region, often with involvement of the...
, etc.
Alzheimer's disease
Alzheimer's diseaseAlzheimer's disease
Alzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death...
(AD) is a progressive, degenerative and fatal brain disease, in which cell to cell connections in the brain are lost. As a result, the death of brain cells occur, therefore giving Alzheimer's disease the title as the most common form of dementia. In the entire world, approximately 1-5% of the population is affected by Alzheimer's disease. It is estimated that 500,000 Canadians currently suffer from Alzheimer’s disease or a related dementia. It is the most significant cause of disability among individuals aged 65 and above. Women are disproportionately the victims of Alzheimer’s disease, with evidence suggesting 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
AmnesiaAmnesia
Amnesia is a condition in which one's memory is lost. The causes of amnesia have traditionally been divided into categories. Memory appears to be stored in several parts of the limbic system of the brain, and any condition that interferes with the function of this system can cause 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
Anterograde 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. This is in contrast to retrograde amnesia, where memories...
and retrograde amnesia
Retrograde amnesia
Retrograde amnesia is a loss of access to events that occurred, or information that was learned, before an injury or the onset of a disease....
, that show hippocampal or medial temporal lobe
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
damage. Anterograde amnesics show difficulty in the learning and retention of information encountered after brain damage. Retrograde Amnesics generally have memories spared about personal experiences or context independent semantic information.
Brain injury
Traumatic brain injuryTraumatic brain injury
Traumatic brain injury , also known as intracranial injury, occurs when an external force traumatically injures the brain. TBI can be classified based on severity, mechanism , or other features...
often occurs from damages to the brain caused by an outside force, and may lead to cases of amnesia depending on the severity of the injury. Head injury
Head injury
Head injury refers to trauma of the head. This may or may not include injury to the brain. However, the terms traumatic brain injury and head injury are often used interchangeably in medical literature....
can give rise to either transient or persisting amnesia. Occasionally, post-traumatic amnesia
Post-traumatic amnesia
Post-traumatic amnesia is a state of confusion that occurs immediately following a traumatic brain injury in which the injured person is disoriented and unable to remember events that occur after the injury. The person may be unable to state his or her name, where he or she is, and what time it...
(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.
In some cases, individuals have reported having a particularly vivid memory for images or sounds occurring immediately before the injury, on regaining consciousness, or during a lucid interval between the injury and the onset of PTA. As a result, recent controversy has emerged about whether severe head injury and amnesia exclude the possibility of post-traumatic stress disorder
Post-traumatic stress disorder
Posttraumaticstress disorder is a severe anxiety disorder that can develop after exposure to any event that results in psychological trauma. This event may involve the threat of death to oneself or to someone else, or to one's own or someone else's physical, sexual, or psychological integrity,...
(PTSD) symptoms. In a study carried out by McMillan (1996), patients reported ‘windows’ of experience, in which emotional disturbance was sufficient to cause PTSD. These 'windows' involved recall of events close to impact (when RA was brief), of distressing events soon after the accident (when PTA was short), or of 'islands' of memory (e.g. hearing the screaming of others).
Brain injuries can also be the result of a stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
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
DementiaDementia
Dementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...
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
Thyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
disease) or irreversible (e.g. Alzheimer's disease). Currently, there are more than 35 million people with dementia worldwide. 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.
Hyperthymestic Syndrome
Hyperthymestic Syndrome causes an individual to have an extremely detailed autobiographical memoryAutobiographical memory
Autobiographical memory is a memory system consisting of episodes recollected from an individual's life, based on a combination of episodic and semantic memory.-Formation:Conway and Pleydell-Pearce proposed that autobiographical...
. Patients with this disorder 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 disorder is very rare with only a few confirmed cases.
Huntington’s Disease
Huntington's DiseaseHuntington's disease
Huntington's disease, chorea, or disorder , is a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and dementia. It typically becomes noticeable in middle age. HD is the most common genetic cause of abnormal involuntary writhing movements called chorea...
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 Huntinton'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; suffers 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.
Parkinson's disease
Parkinson's diseaseParkinson's disease
Parkinson's disease is a degenerative disorder of the central nervous system...
(PD) is a neurodegenerative disease. Movement is normally controlled by dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
; 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. 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.
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.
Wernicke-Korsakoff’s Syndrome
Wernicke-Korsakoff syndromeWernicke-Korsakoff syndrome
Wernicke–Korsakoff syndrome is a manifestation of thiamine deficiency, or beriberi. This is usually secondary to alcohol abuse...
(WKS) is a severe neurological disorder caused by thiamine
Thiamine
Thiamine or thiamin or vitamin B1 , named as the "thio-vitamine" is a water-soluble vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B1. Its phosphate derivatives are...
(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
Confabulation
Confabulation is the process in which a memory is remembered falsely. Confabulations are indicative of a complicated and intricate process that can be led astray at any given point during encoding, storage, or recall of a memory. Two distinct types of confabulation are often distinguished...
(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 affects of alcohol consumption and from periods of alcohol withdrawal.
Case studies
A.J. (patient)A.J. suffered from a rare memory disorder called hyperthymestic syndrome. She had an inability to forget. Her autobiographical memory
Autobiographical memory
Autobiographical memory is a memory system consisting of episodes recollected from an individual's life, based on a combination of episodic and semantic memory.-Formation:Conway and Pleydell-Pearce proposed that autobiographical...
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
Clive Wearing is a British musicologist, conductor, and keyboardist suffering from an acute and long-lasting case of anterograde and retrograde amnesia, meaning that he lacks the ability to form new memories.-Musical career:...
Clive Wearing suffered from anterograde amnesia after a rare case of Herpes Simplex Virus
Herpes simplex virus
Herpes simplex virus 1 and 2 , also known as Human herpes virus 1 and 2 , are two members of the herpes virus family, Herpesviridae, that infect humans. Both HSV-1 and HSV-2 are ubiquitous and contagious...
I (HSV-I) which targeted and attacked the spinal column and brain. The virus led to a case of encephalitis
Encephalitis
Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...
which caused the brain damage of his hippocampus, resulting in his amnesia.
HM (patient)
HM (patient)
Henry Gustav Molaison , famously known as HM or H.M., was an American memory disorder patient who was widely studied from late 1957 until his death...
H.M. suffered from epileptic seizures and had his medial temporal lobes surgical removed to prevent or decrease the occurrence of the seizures. After the removal of H.M.'s medial temporal lobes, he suffered from anterograde amnesia as well as moderate retrograde amnesia. H.M. was still able to retain procedural memory
Procedural memory
Procedural memory is memory for how to do things. Procedural memory guides the processes we perform and most frequently resides below the level of conscious awareness. When needed, procedural memories are automatically retrieved and utilized for the execution of the integrated procedures involved...
after the surgery.
KC (patient)
KC (patient)
Patient KC is a widely studied Canadian memory disorder patient who has been used as a case study in over 20 neuropsychology papers over the span of the past 25 years. In 1981, KC was involved in a motorcycle accident that left him with severe anterograde amnesia, as well as temporally graded...
"The extent of damage to K.C.’s medial temporal lobes, particularly to his hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...
and parahippocampal gyrus
Parahippocampal gyrus
The parahippocampal gyrus is a grey matter cortical region of the brain that surrounds the hippocampus. This region plays an important role in memory encoding and retrieval....
, and associated diencephalic and basal forebrain
Basal forebrain
The basal forebrain is a collection of structures located ventrally to the striatum. It is considered to be the major cholinergic output of the central nervous system . It includes a group of structures that lie near the bottom of the front of the brain, including the nucleus basalis, diagonal band...
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
Spatial memory
In cognitive psychology and neuroscience, spatial memory is the part of memory responsible for recording information about one's environment and its spatial orientation. For example, a person's spatial memory is required in order to navigate around a familiar city, just as a rat's spatial memory is...
."
Memory disorders and 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 geneticsGenetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
and neural degeneration
Neurodegeneration
Neurodegeneration is the umbrella term for the progressive loss of structure or function of neurons, including death of neurons. Many neurodegenerative diseases including Parkinson’s, Alzheimer’s, and Huntington’s occur as a result of neurodegenerative processes. As research progresses, many...
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
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
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.
Apolipoprotein E
Apolipoprotein E is a class of apolipoprotein found in the chylomicron and IDLs that binds to a specific receptor on liver cells and peripheral cells. It is essential for the normal catabolism of triglyceride-rich lipoprotein constituents.-Function:...
(ApoE4) allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
(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
Genetic marker
A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify cells, individuals or species. It can be described as a variation that can be observed...
.
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
Cholinergic
The word choline generally refers to the various quaternary ammonium salts containing the N,N,N-trimethylethanolammonium cation. Found in most animal tissues, choline is a primary component of the neurotransmitter acetylcholine and functions with inositol as a basic constituent of lecithin...
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.
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 in Canada alone, as well as globally. In 2050, there could be an epidemic of neurological diseases. With an every growing baby-boom population, and the prevalence of mental illness growing, an increase in demand for better mental health care is relevant.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 While prejudiced views may have started out with a kernel of truth, the level of services available to an ever aging and memory-impaired demographic will need to increase as well.
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.
One is deemed to be mentally ill if there is an imbalance of hot-cold/wet-dry, and the proper functioning of the nerves, heart, liver, lungs, kidneys, and spleen. In an event of an imbalance, it 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 either suspense to be created through retrograde or traumatic amnesia as seen in Alfred HitchcockAlfred Hitchcock
Sir Alfred Joseph Hitchcock, KBE was a British film director and producer. He pioneered many techniques in the suspense and psychological thriller genres. After a successful career in British cinema in both silent films and early talkies, Hitchcock moved to Hollywood...
’s Spellbound
Spellbound
- Film and television :* Spellbound , with Lois Meredith* Spellbound , directed by John Harlow* Spellbound , directed by Alfred Hitchcock and starring Ingrid Bergman and Gregory Peck...
. It can also provide comic relief if one introduces a character who has short-term memory impairments.
Some examples from movies and television shows that often depict characters suffering from memory disorders include:
- Denny Crane, a character from the television show Boston LegalBoston LegalBoston Legal is an American legal dramedy created by David E. Kelley, which was produced in association with 20th Century Fox Television for the ABC...
shows cognitive impairment that could be indicative to Alzheimer’s disease. - Dr. Philip Brainard a character in the movie The Absent-Minded ProfessorThe Absent-Minded ProfessorThe Absent-Minded Professor is a 1961 black-and-white Walt Disney Productions film based on the short story A Situation of Gravity, by Samuel W. Taylor....
displays mild memory impairment. - The character Dory from the movie Finding NemoFinding NemoFinding Nemo is a 2003 American comi-drama animated film written by Andrew Stanton, directed by Andrew Stanton and Lee Unkrich and produced by Pixar. It tells the story of the overly protective clownfish Marlin who, along with a regal tang called Dory , searches for his abducted son Nemo...
shows severe short term memory loss. - The celebrity and actor Michael J. FoxMichael J. FoxMichael J. Fox, OC is a Canadian American actor, author, producer, activist and voice-over artist. With a film and television career spanning from the late 1970s, Fox's roles have included Marty McFly from the Back to the Future trilogy ; Alex P...
has been diagnosed with Parkinson's disease. - The character Savant (comics)Savant (comics)Savant is a comic book character from DC Comics.-Fictional character biography:Brian Durlin, better known as Savant, is the spoiled heir to an enormous fortune. Savant had moved to Gotham to become a self-styled vigilante...
, a member of the DC Comics superhero team the Birds of Prey (comics), exhibits both photographic and non-linear memory as a result of what is only described as "a chemical imbalance". - Iris MurdochIris MurdochDame Iris Murdoch DBE was an Irish-born British author and philosopher, best known for her novels about political and social questions of good and evil, sexual relationships, morality, and the power of the unconscious...
- British writer and philosopher who developed Alzheimer's disease and portrayed by Kate WinsletKate WinsletKate Elizabeth Winslet is an English actress and occasional singer. She has received multiple awards and nominations. She was the youngest person to accrue six Academy Award nominations, and won the Academy Award for Best Actress for The Reader...
in the film Iris in 2001 - The NotebookThe NotebookThe Notebook is a 1996 romantic novel by American novelist Nicholas Sparks, based on a true story. The novel was later adapted into a popular romance film by the same name in 2004.-Background:...
(2004) the film based on the novel by Nicholas Sparks(1996) a character, Allie Hamilton played by Rachel McAdamsRachel McAdamsRachel Anne McAdams is a Canadian actress. After graduating from a theatre program at York University, Toronto in 2001, she worked steadily as an actress until finding fame in 2004 with starring roles in teen comedy Mean Girls and romantic drama The Notebook...
that developed Alzheimer's disease.