Chapter_15_Summary_Outline - Chapter 15 Cognitive Disorders...

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Chapter 15: Cognitive Disorders Overview/Summary The DSM-IV recognizes various cognitive disorders, including delirium, dementia, and amnestic disorder. Typically, these disorders result from transient or permanent damage t o the brain. Chronic neuropsychological disorders involve permanent loss of neural cells. The primary causes of brain tissue destruction are many and varied; common ones include certain infectious diseases (such as the HIV-1 virus), brain tumors, physical trau ma (injuries and alcohol), degenerative processes (as in Alzheimer’s disease), and cerebr ovascular arteriosclerosis, often manifested as vascular dementia. There is no simple relat ionship between the extent of brain damage and degree of impaired functioning. Some pe ople who have severe damage develop no severe symptoms, while others with slight dam age have extreme reactions. Although such inconsistencies are not completely understood , it appears that an individual’s premorbid personality and life situation are important in d etermining his or her reactions to brain damage. The APOE-4 genetic allele may also be i mportant. Delirium is a fluctuating condition common among the elderly. It involves a state of awareness between wakefulness and stupor or coma. It is treated with neuroleptic medica tions and also with benzodiazepines. Dementia involves a loss of function and of previously acquired skills. It has a slow onset and a deteriorating course. The most common cause of dementia is Alzheimer’s disease. Age is a major risk factor for Alzheimer’s disease as well as other forms of dementia, suc h as vascular dementia. Genes play a major role in creating susceptibility and risk for Alzheimer’s disease. Genetic mutations of the APP, presenilin 1 and presenilin 2 genes are implicated in early onset AD. The APOE-4 allele of the APOE gene is also a risk factor for AD. Interestingly , substantial numbers of MZ twins are discordant for AD suggesting that genetic suscepti bility interacts with environmental factors. Environmental factors include diet, exposure t o metals such as aluminum, and experiencing head trauma The characteristic neuropathology of Alzheimer’s disease involves cell loss, senile plaques and neurofibrillary tangles. Plaques contain a sticky protein called beta amyloid. Neurofibrillary tangles contain abnormal tau protein. Alzheimer’s disease causes a destru ction of cells that make acetylcholine, a neurotransmitter important for memory. Drug tre atments for AD include cholinesterase inhibitors such as donepezil (Aricept). These drugs help stop ACh being broken down and so make more of it available to the brain. Amnestic disorders involve severe memory loss. The most common cause of amnestic disorders is chronic alcohol abuse. Head injuries can cause amnesia as well as other cogni tive impairments. Retrograde amnesia is the ability to recall events before the accident. A nterograde amnesia is the inability to remember things since the accident.
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Chapter_15_Summary_Outline - Chapter 15 Cognitive Disorders...

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