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Chapter 3

PSYC32 (31) Week 2 Notes on Chapter 3.docx

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Zachariah Campbell

PSYC31H3 Week 2 Notes on Chapter 3 Introduction: • Neurodegenerative disorders: Disorders that involve progressive loss of function or destruction of neurons or various structures of the brain. • Acquired disorders: Disorders caused by an accident, insult, or disease process coming from a source outside of the cortex. • Knowledge of the various difficulties which an individual may sustain is crucial for a clinical neuropsychologist. The roles of conducting assessment, applying a diagnosis, and undertaking treatment all require the professional to have a working understanding of the various ailments, their etiology or causal factors, if known, course of illness, prognosis, and rehabilitation. • Another reason why it is necessary to understand the clinically presented symptoms and the causes of various disorders is that, very often, dissimilar difficulties present themselves with similar symptomology. A common example is the distinction between dementia, with its multiple causes, and depression. Both dementia and depression may reflect sadness, concentration and attention difficulties, vegetative signs such as sleeping and eating difficulties and other similar symptoms. However, the causal factors are clearly dissimilar and require very different treatment plans and rehabilitation strategies. • Another factor to consider is that the majority of central nervous system diseases or difficulties involve depression as a secondary symptom, which suggests that it is a reaction to the primary diagnosis. Degenerative Disorders: • By the nature of the term, degenerative disorders involve difficulties with destruction of neurons and/or specific areas within the central nervous system. In many of these difficulties, the loss of neurons or neural tissue is not repairable and the loss of abilities is permanent. The etiological factors are unknown for many of the degenerative disorders. These disorders tend to occur more often in the older population and as the population as a whole ages, more and more of these disorders are surfacing. Cortical Dementias: • Cortical Dementia refers to damage within the cerebral cortex and demonstrates a progressive decline in cognitive abilities. Memory and other higher order functions such as reasoning and the ability to do abstract through are examples of the types of cognitive abilities lost with dementia. • Dementia takes a downward course with the result being the death of the individual. During the early stages of degenerative disorders, differences usually appear. As the disease process progresses, patients with different etiologies tend to show many similar symptoms, which often makes the diagnosis more difficult. • Dementia is usually described in reference to behaviours falling within three stages.  Stage one involves behaviours that may deviate from the norm for the individual. The individual himself or herself may not be aware of the changes at this time.  During stage two of dementia, the individual often notices memory problems and tries to conceal them from others. Confabulation may occur, similar to individuals who consume large amounts of alcohol, in which the individual develops a cover story or excuse for the lack of memory. As stage two progresses, the individual may become geographically lost or wander and may engage in activities which are dangerous to self and others.  Sundowning: In patients with dementia, the worsening of symptoms as the day progresses.  Stage three involves serious cognitive deterioration in addition to problems associated with self-care. Many families find that an individual with stage three dementia requires care outside of the family environment. • Individuals usually do not die from dementia, but from some others opportunistic agent which invades a nonintact central nervous system. A central nervous system that has significant impairment in neurological tissue is not able to fight off viruses or any other invading process as a full intact central nervous system. Alzheimer’s Type Dementia: • Alzheimer’s Type Dementia: Dementia characterized by neurofibrillary tangles and amyloid plaques; a diagnosis cannot be made until autopsy but is termed Alzheimer’s type based on behavioural symptoms. • Alzheimer’s disease is characterized by neurofibrillary tangles and amyloid plaques. Neurofibrillary tangles are made from tau proteins and develop when microtubules, which transport substances from the soma to the end of the axon, become twisted. Tau is the protein which maintains the microtubules’ structure, but in Alzheimer’s disease it is altered, which allows the twisted microtubules to group together into tangles. The volume of these tangles obstructs living tissue and often strangles it. • Amyloid Plaques: Deposits of aluminum silicate and amyloid peptides believed to cause loss of neurons and vascular damage. • These plaques also obstruct living tissue. It is important to note that the plaques and tangles appear in normally aging individuals and individuals with other degenerative diseases. The key to a diagnosis of Alzheimer’s disease is the extent of the tangles and plaques and the regions of the brain they gravitate toward. • Loss of neurons is another common feature of Alzheimer’s disease, particularly in the temporal area. If neurons are no longer able to communicate with major memory areas within the cortex, significant memory loss may occur. • Loss of neurons also leads to changes in anatomical structures, which may point to the enlargement of ventricles with Alzheimer’s disease. • Alzheimer’s disease has an inherited genetic component. If an individual has a first- degree relative (parent or sibling) with the disease, it doubles the person’s chances of acquiring the disease compared to those without affected first-degree relatives. • The other three well-established risk factors for Alzheimer’s disease are age, the gene for the protein apolipoprotein E (Apo E) on chromosome 19, and Down syndrome. Apo E is a normally occurring protein that helps carry phospholipids and cholesterol within the body, the E4 allele has been linked to various diseases such as Alzheimer’s disease. • Allele: Any one of a number of viable DNA codings that occupy a given position on a chromosome. • Down syndrome is the most frequent cause of mental retardation and is caused by a trisomy on chromosome 21. Almost all individuals with Down syndrome show mental and physical deterioration characteristic of Alzheimer’s disease if they live longer than 30-40 years. • Additional causes of Alzheimer’s disease have been investigated but are controversial. Traumatic brain injury is one suspected precursor to Alzheimer’s disease. It appears that the more serious the injury, the more likely it is the individual will develop Alzheimer’s disease. • A low level of estrogen in postmenopausal women is another theory which has been proposed for Alzheimer’s disease. • Treatment for Alzheimer’s disease may involve preventive measures such as drinking red wine, which contains antioxidants that may have a protective effect. Medications which stop the development of amyloid plaques have been developed. Other medications that keep tau in its normal form have also been explored. Frontotemporal Dementias: • Frontotemporal dementias (FTDs) are degenerative disorders of the frontal and temporal lobes with the remainder of the cortex maintaining relative integrity. These difficulties have a slow onset and progression. The age of onset is usually between 40 and 65 years of age. • The symptoms of FTD and Alzheimer’s disease are extremely similar and, in later stages, almost indistinguishable. Changes in social behaviour and personality, lack of insight and stereotypic behaviours such as the repeating of a behavioural sequence, and eating a great deal of food, best differentiate frontotemporal dementia patients from those with great deal of food, best differentiate frontotemporal dementia patients from those with Alzheimer’s disease. • Other common features of FTD include speech and language changes, extrapyramidal symptoms, and primitive reflexes. • The pattern of decline will vary between patients and often is based on whether decline is more extensive in the frontal or the temporal area. The parietal and occipital lobes are often spared any type of deterioration. • The type of social and emotional behaviour deficits exhibited are similar to those previously described as FTD. The difference, which sets Pick’s disease apart from other FTDs, is the presence of Pick Bodies compromised of tau proteins, which are shaped differently than the neurofibrillary tangles seen in Alzheimer’s disease. Dementia with Lewy Bodies: • Dementia with Lewy Bodies (DLB) accounts for approximately 20% of patients with dementia. • The symptoms of DLB includes progressive dementia, extrapyramidal signs similar to Parkinson’s disease (PD), visual hallucinations, delusions, and possibly severe cognitive fluctuations. • In common with patients with Alzheimer’s disease, patients with DLB frequently have an elevated ApoE4 allele. DLB is somewhat more common in men, usually occurring after the age of 50. • The distinct pathological finding in this disorder is the presence of Lewy bodies, which are protein deposits found throughout the cortex, paralimbic areas, and the substantia nigra. • Individuals who have DLB have shown improvement in cognition and behaviour using cholinesterase inhibitors. Subcortical Dementias: • Subcortical dementias are dementias that affect subcortical brain structures. The distinction between cortical and subcortical dementias is largely behaviourally based. The behavioral changes that differentiate subcortical dementias from cortical dementias include:  (a) Cognitive slowing with problems in attention and concentration, executive disturbances including impaired concept manipulation, visuospatial abnormalities, and memory difficulties that affect retrieval more than new learning.  (b) Absence of aphasia (loss of expressive or receptive language), apraxia (inability to perform purposeful movements), and agnosia (inability to recognize sensory input).  (c) emotional features including apathy, depression, and personality changes.  In summary, the cognitive functions involved include disabilities related to arousal, attention, processing speed, motivation, and emotion, as opposed to the involvement of higher order functioning as in cortical dementias. • Many of the subcortical dementias have movement difficulties as a major symptom of the disease. This usually involves the extrapyramidal motor system, which modulates movement and maintains muscle tone and posture. Very often, the movements seen in in subcortical dementia appear to be uncontrollable or they are jerky, halting, or rigid. Parkinson’s Disease/Parkinsonism: • Parkinson’s disease (PD) is a movement disorder with attendant symptoms. It was originally described by Parkinson in 1817 as an involuntary tremulous motion with lessened muscle power. Symptoms in addition to shaking may include the aforementioned lessened muscular power, difficulty moving from resting to walking and vice versa, a tendency to bend forward while walking, and cognitive and emotional sequelae. Almost always present is a “resting tremor,” which disappears during movement and in sleep, as well as slowed moving pace. Another classic symptoms is the lack of facial expressions often referred to as “masked faces.” • Depression is one of the most common symptoms of PD or Parkinsonism with estimates ranging from 40%-60% pf patients. Parkinson’s disease is associated with the depletion of the neurotransmitter dopamine in the basal ganglia, subthalamic nucleus, susbtantia nigra, and the interconnections to each other and to thalamic nuclei. • It typically affects individuals in their 50s. There are studies that indicate a family pattern that may point to the hypothesis of genetic inheritance. Possibly related to the appearance of PD is traumatic brain injury such as in the case of former boxer Muhammad Ali who was repeatedly hit in the frontal lobes during his boxing matches. • Treatment for PD has several components. Medical treatment focuses on the alleviation of symptoms or curtailing progression. • L-Dopa began to be used for the aforementioned issues in 1967 to replace dopamine depletion in the substantia nigra. • Other medication have been used either alone or in addition to L-dope. Most are anticholinergic medications to deal with motor symptoms but have an adverse effect on selective attention and planning. • Surgical treatments including lesioning or placing a deep brain stimulator in several regions of the Globus pallidus, subthalamic nuclei, or ventral intermediate thalamic nuclei have been relatively successful. Huntington’s Disease: • Once termed Huntington’s chorea. The spasmodic symptoms are very blatant and involve involuntary movements that become disabling because of their severity. Huntington’s disease also has cognitive and personality impairments. In a sense, the dementia strikes at all of the functions of the human being – motor, cognitive, and emotional behaviours. Huntington’s disease is anatomically caused by atrophy of the GABAergic neurons of the caudate nucleus and putamen in the corpus striatum. Gamma-aminobutyric acid (GABA) is the most common inhibitory neurotransmitter. The atrophy may also affect the cerebellum, thalamic nuclei, and other subcortical tissue. • Huntington’s disease is steadily progressive disease, which tends to affect an individual anywhere between 10-20 years of age. • As the disease runs its full course, pneumonia is the most common cause of death. • Huntington’s disease is a hereditary condition. For many years, Huntington’s disease was passed from generation to generation because of lack of knowledge regarding its cause. • Huntington’s disease is caused by an excess number of trinucleotide CAG repeats (cytosine, adenine, and guanine) on chromosome 4. This is an autosomal dominant disease and has 100% penetrance so that half of all offspring of a carrier parent will acquire the disease if they live long enough. • Unfortunately, treatment for patients with Huntington’s disease tends to be palliative, in the sense of making the person as comfortable as possible. Neuroleptic medications are most often used to deal with the spasmodic movements. It tends to be the case that whatever mediation is used alleviates some symptoms but at the same time introduces more side effects or increase other symptoms. Progressive Supranuclear Palsy: • Also known as Steel-Richardson-Olszewski disorder. • The classic feature of this disorder is an inability to look downward on command. Similar motor, cognitive, and emotional disturbances observed in other subcortical dementias occur with progressive supranuclear palsy. • The progression of cognitive decline appears to be greater than in the other disorders already described and is consistent with degeneration of both cortical and subcortical regions. The sites of lesions in progressive supranuclear palsy are in the upper brain stem to the basal ganglia and may include the limbic structures and the basal ganglia. The degenerative process appears to disconnect ascending pathways from these structures to the prefrontal cortex. • Progressive supranuclear palsy is a nonfamilial condition that tends to develop in one’s 60s. • Progressive supranuclear palsy has had limited response to dopaminergic or anticholinergic drugs even though symptoms resemble PD. The emotional symptoms may be treated with antidepressants. Progressive Disorders of the Central Nervous System: Multiple Sclerosis: • Multiple sclerosis (MS) is a disease caused by the destruction of the myelin sheath which covers the axons of neurons. As described earlier, myelin facilitates neural conduction. At the demyelinated sites, multiple discrete plaques are formed by astrocytes. The size of the plaques varies from 1 mm to several centimeters. • Classic symptoms include weakness, stiffness, lack of coordination, gait disturbances, bladder and bowel difficulties, sexual dysfunction, sensory changes, heat sensitivity, and fatigue. • Cognitive impairment is evident in 40-60% of patients but may be difficult to detect, particularly during the initial stages. Intellectual functioning is significantly affected in about 20% of patients, and memory is one of the most commonly affected areas. The extent of cognitive deficits is related to the location and extent of damage. • Multiple sclerosis is characterized as a relapsing and remitting disorder. It has all of the hallmarks of a progressive disorder but often exhibits static periods where the progression ceases but the lost functions are never regained. Multiple sclerosis tends to follow one of several courses. These including the following:  Relapsing-remitting, The most common; it is characterized by clearly defined disease relapses. Recovery can be full or with sequelae and residual deficit. No progression of disease between relapses.  Secondary-Progressive. The next most common type. First characterized by relapsing remitting course then progression. Relapses and remissions may or may not occur.  Primary-Progressive. The next most common type. There is unremitting disease progression from onset for most patients, but occasional stabilization and even improvement in functioning in others. No clear relapse.  Progressive-relapsing. The least common type. Disease progression occurs from onset. Acute relapses also occur from which patients may or may not fully recover. • Multiple sclerosis generally does not shorten the life span of the individual. • The etiology of MS involves multiple factors. Genetic factors influence susceptibility and autoimmune diseases are more common in the first degree relatives of patients with MS. • Grant found patients with MS, compared to healthy adults, to have experienced qualitatively more extreme stressful events. However, this does not prove cause and effect and can be biased by self-report. These type of findings may also explain the relapsing-remitting nature of the disorder. • Injectable medications (B-interferons and glatiramer acetate) supress immunoactivity. • Each medication has a different effect but al impact disease activity, reducing relapse rates and stopping new lesion formation. High-dose corticopsychological effects have been shown with the use of medications in that there has been an increase in cognitive and memory functioning. Cholinesterase inhibitors developed to treat dementia has improved cognitive function in patients with MS. • Counseling for emotional sequelae has proved to be beneficial. Also, cognitive rehabilitation programs for cogni
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