{"id":4021,"date":"2017-03-27T18:42:24","date_gmt":"2017-03-27T18:42:24","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/wm-biology2\/?post_type=chapter&#038;p=4021"},"modified":"2024-04-26T01:11:08","modified_gmt":"2024-04-26T01:11:08","slug":"neurodegenerative-disorders","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wm-biology2\/chapter\/neurodegenerative-disorders\/","title":{"raw":"Neurodegenerative Disorders","rendered":"Neurodegenerative Disorders"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Identify key characteristics and symptoms of neurodegenerative disorders<\/li>\r\n<\/ul>\r\n<\/div>\r\n<b>Neurodegenerative disorders<\/b> are illnesses characterized by a loss of nervous system functioning that are usually caused by neuronal death. These diseases generally worsen over time as more and more neurons die. The symptoms of a particular neurodegenerative disease are related to where in the nervous system the death of neurons occurs. Spinocerebellar ataxia, for example, leads to neuronal death in the cerebellum. The death of these neurons causes problems in balance and walking. Neurodegenerative disorders include Huntington\u2019s disease, amyotrophic lateral sclerosis, Alzheimer\u2019s disease and other types of dementia disorders, and Parkinson\u2019s disease. Here, Alzheimer\u2019s and Parkinson\u2019s disease will be discussed in more depth.\r\n<h2>Alzheimer\u2019s Disease<\/h2>\r\n<b>Alzheimer\u2019s disease<\/b> is the most common cause of dementia in the elderly. In 2012, an estimated 5.4 million Americans suffered from Alzheimer\u2019s disease, and payments for their care are estimated at $200 billion. Roughly one in every eight people age 65 or older has the disease. Due to the aging of the baby-boomer generation, there are projected to be as many as 13 million Alzheimer\u2019s patients in the United States in the year 2050.\r\n\r\nSymptoms of Alzheimer\u2019s disease include disruptive memory loss, confusion about time or place, difficulty planning or executing tasks, poor judgment, and personality changes. Problems smelling certain scents can also be indicative of Alzheimer\u2019s disease and may serve as an early warning sign. Many of these symptoms are also common in people who are aging normally, so it is the severity and longevity of the symptoms that determine whether a person is suffering from Alzheimer\u2019s.\r\n\r\nAlzheimer\u2019s disease was named for Alois Alzheimer, a German psychiatrist who published a report in 1911 about a woman who showed severe dementia symptoms. Along with his colleagues, he examined the woman\u2019s brain following her death and reported the presence of abnormal clumps, which are now called amyloid plaques, along with tangled brain fibers called neurofibrillary tangles. Amyloid plaques, neurofibrillary tangles, and an overall shrinking of brain volume are commonly seen in the brains of Alzheimer\u2019s patients. Loss of neurons in the hippocampus is especially severe in advanced Alzheimer\u2019s patients. Figure\u00a01 compares a normal brain to the brain of an Alzheimer\u2019s patient. Many research groups are examining the causes of these hallmarks of the disease.\r\n\r\nOne form of the disease is usually caused by mutations in one of three known genes. This rare form of early onset Alzheimer\u2019s disease affects fewer than five percent of patients with the disease and causes dementia beginning between the ages of 30 and 60. The more prevalent, late-onset form of the disease likely also has a genetic component. One particular gene, apolipoprotein E (APOE) has a variant (E4) that increases a carrier\u2019s likelihood of getting the disease. Many other genes have been identified that might be involved in the pathology.\r\n<div class=\"textbox\">Visit <a href=\"http:\/\/www.alz.org\/research\/science\/alzheimers_disease_causes.asp\" target=\"_blank\" rel=\"noopener\">this website for video links discussing genetics and Alzheimer\u2019s disease<\/a>.<\/div>\r\nUnfortunately, there is no cure for Alzheimer\u2019s disease. Current treatments focus on managing the symptoms of the disease. Because decrease in the activity of cholinergic neurons (neurons that use the neurotransmitter acetylcholine) is common in Alzheimer\u2019s disease, several drugs used to treat the disease work by increasing acetylcholine neurotransmission, often by inhibiting the enzyme that breaks down acetylcholine in the synaptic cleft. Other clinical interventions focus on behavioral therapies like psychotherapy, sensory therapy, and cognitive exercises. Since Alzheimer\u2019s disease appears to hijack the normal aging process, research into prevention is prevalent. Smoking, obesity, and cardiovascular problems may be risk factors for the disease, so treatments for those may also help to prevent Alzheimer\u2019s disease. Some studies have shown that people who remain intellectually active by playing games, reading, playing musical instruments, and being socially active in later life have a reduced risk of developing the disease.\r\n\r\n[caption id=\"attachment_2688\" align=\"aligncenter\" width=\"1024\"]<img class=\"size-large wp-image-2688\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/07211827\/Figure_35_05_01-1024x457.jpg\" alt=\"A cross section of a normal brain and the brain of an Alzheimer\u2019s patient are compared. In the Alzheimer\u2019s brain, the cerebral cortex is greatly shrunken in size as is the hippocampus. Ventricles, holes in the center and bottom right and left parts of the brain, are also enlarged.\" width=\"1024\" height=\"457\" \/> Figure\u00a01.\u00a0Compared to a normal brain (left), the brain from a patient with Alzheimer\u2019s disease (right) shows a dramatic neurodegeneration, particularly within the ventricles and hippocampus. (credit: modification of work by \u201cGarrando\u201d\/Wikimedia Commons based on original images by ADEAR: \"Alzheimer's Disease Education and Referral Center, a service of the National Institute on Aging\u201d)[\/caption]\r\n<h2>Parkinson\u2019s Disease<\/h2>\r\nLike Alzheimer\u2019s disease, <b>Parkinson\u2019s disease<\/b> is a neurodegenerative disease. It was first characterized by James Parkinson in 1817. Each year, 50,000-60,000 people in the United States are diagnosed with the disease. Parkinson\u2019s disease causes the loss of dopamine neurons in the substantia nigra, a midbrain structure that regulates movement. Loss of these neurons causes many symptoms including tremor (shaking of fingers or a limb), slowed movement, speech changes, balance and posture problems, and rigid muscles. The combination of these symptoms often causes a characteristic slow hunched shuffling walk, illustrated in Figure\u00a02. Patients with Parkinson\u2019s disease can also exhibit psychological symptoms, such as dementia or emotional problems.\r\n\r\n[caption id=\"\" align=\"alignright\" width=\"300\"]<img id=\"5\" class=\"\" src=\"https:\/\/openstax.org\/resources\/47580c08b6399ca04707aa4eaa051118cd41f37f\" alt=\"Illustration shows a hunched man with stiff arms and a shuffling walk.\" width=\"300\" height=\"317\" data-media-type=\"image\/jpg\" \/> Figure 2. Parkinson\u2019s patients often have a characteristic hunched walk.[\/caption]\r\n\r\nAlthough some patients have a form of the disease known to be caused by a single mutation, for most patients the exact causes of Parkinson\u2019s disease remain unknown: the disease likely results from a combination of genetic and environmental factors (similar to Alzheimer\u2019s disease). Post-mortem analysis of brains from Parkinson\u2019s patients shows the presence of Lewy bodies\u2014abnormal protein clumps\u2014in dopaminergic neurons. The prevalence of these Lewy bodies often correlates with the severity of the disease.\r\n\r\nThere is no cure for Parkinson\u2019s disease, and treatment is focused on easing symptoms. One of the most commonly prescribed drugs for Parkinson\u2019s is L-DOPA, which is a chemical that is converted into dopamine by neurons in the brain. This conversion increases the overall level of dopamine neurotransmission and can help compensate for the loss of dopaminergic neurons in the substantia nigra. Other drugs work by inhibiting the enzyme that breaks down dopamine.\r\n<div class=\"textbox tryit\">\r\n<h3>Try It<\/h3>\r\nhttps:\/\/assess.lumenlearning.com\/practice\/fea2e45e-c921-4339-abec-6393f4c8438c\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Identify key characteristics and symptoms of neurodegenerative disorders<\/li>\n<\/ul>\n<\/div>\n<p><b>Neurodegenerative disorders<\/b> are illnesses characterized by a loss of nervous system functioning that are usually caused by neuronal death. These diseases generally worsen over time as more and more neurons die. The symptoms of a particular neurodegenerative disease are related to where in the nervous system the death of neurons occurs. Spinocerebellar ataxia, for example, leads to neuronal death in the cerebellum. The death of these neurons causes problems in balance and walking. Neurodegenerative disorders include Huntington\u2019s disease, amyotrophic lateral sclerosis, Alzheimer\u2019s disease and other types of dementia disorders, and Parkinson\u2019s disease. Here, Alzheimer\u2019s and Parkinson\u2019s disease will be discussed in more depth.<\/p>\n<h2>Alzheimer\u2019s Disease<\/h2>\n<p><b>Alzheimer\u2019s disease<\/b> is the most common cause of dementia in the elderly. In 2012, an estimated 5.4 million Americans suffered from Alzheimer\u2019s disease, and payments for their care are estimated at $200 billion. Roughly one in every eight people age 65 or older has the disease. Due to the aging of the baby-boomer generation, there are projected to be as many as 13 million Alzheimer\u2019s patients in the United States in the year 2050.<\/p>\n<p>Symptoms of Alzheimer\u2019s disease include disruptive memory loss, confusion about time or place, difficulty planning or executing tasks, poor judgment, and personality changes. Problems smelling certain scents can also be indicative of Alzheimer\u2019s disease and may serve as an early warning sign. Many of these symptoms are also common in people who are aging normally, so it is the severity and longevity of the symptoms that determine whether a person is suffering from Alzheimer\u2019s.<\/p>\n<p>Alzheimer\u2019s disease was named for Alois Alzheimer, a German psychiatrist who published a report in 1911 about a woman who showed severe dementia symptoms. Along with his colleagues, he examined the woman\u2019s brain following her death and reported the presence of abnormal clumps, which are now called amyloid plaques, along with tangled brain fibers called neurofibrillary tangles. Amyloid plaques, neurofibrillary tangles, and an overall shrinking of brain volume are commonly seen in the brains of Alzheimer\u2019s patients. Loss of neurons in the hippocampus is especially severe in advanced Alzheimer\u2019s patients. Figure\u00a01 compares a normal brain to the brain of an Alzheimer\u2019s patient. Many research groups are examining the causes of these hallmarks of the disease.<\/p>\n<p>One form of the disease is usually caused by mutations in one of three known genes. This rare form of early onset Alzheimer\u2019s disease affects fewer than five percent of patients with the disease and causes dementia beginning between the ages of 30 and 60. The more prevalent, late-onset form of the disease likely also has a genetic component. One particular gene, apolipoprotein E (APOE) has a variant (E4) that increases a carrier\u2019s likelihood of getting the disease. Many other genes have been identified that might be involved in the pathology.<\/p>\n<div class=\"textbox\">Visit <a href=\"http:\/\/www.alz.org\/research\/science\/alzheimers_disease_causes.asp\" target=\"_blank\" rel=\"noopener\">this website for video links discussing genetics and Alzheimer\u2019s disease<\/a>.<\/div>\n<p>Unfortunately, there is no cure for Alzheimer\u2019s disease. Current treatments focus on managing the symptoms of the disease. Because decrease in the activity of cholinergic neurons (neurons that use the neurotransmitter acetylcholine) is common in Alzheimer\u2019s disease, several drugs used to treat the disease work by increasing acetylcholine neurotransmission, often by inhibiting the enzyme that breaks down acetylcholine in the synaptic cleft. Other clinical interventions focus on behavioral therapies like psychotherapy, sensory therapy, and cognitive exercises. Since Alzheimer\u2019s disease appears to hijack the normal aging process, research into prevention is prevalent. Smoking, obesity, and cardiovascular problems may be risk factors for the disease, so treatments for those may also help to prevent Alzheimer\u2019s disease. Some studies have shown that people who remain intellectually active by playing games, reading, playing musical instruments, and being socially active in later life have a reduced risk of developing the disease.<\/p>\n<div id=\"attachment_2688\" style=\"width: 1034px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2688\" class=\"size-large wp-image-2688\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/07211827\/Figure_35_05_01-1024x457.jpg\" alt=\"A cross section of a normal brain and the brain of an Alzheimer\u2019s patient are compared. In the Alzheimer\u2019s brain, the cerebral cortex is greatly shrunken in size as is the hippocampus. Ventricles, holes in the center and bottom right and left parts of the brain, are also enlarged.\" width=\"1024\" height=\"457\" \/><\/p>\n<p id=\"caption-attachment-2688\" class=\"wp-caption-text\">Figure\u00a01.\u00a0Compared to a normal brain (left), the brain from a patient with Alzheimer\u2019s disease (right) shows a dramatic neurodegeneration, particularly within the ventricles and hippocampus. (credit: modification of work by \u201cGarrando\u201d\/Wikimedia Commons based on original images by ADEAR: &#8220;Alzheimer&#8217;s Disease Education and Referral Center, a service of the National Institute on Aging\u201d)<\/p>\n<\/div>\n<h2>Parkinson\u2019s Disease<\/h2>\n<p>Like Alzheimer\u2019s disease, <b>Parkinson\u2019s disease<\/b> is a neurodegenerative disease. It was first characterized by James Parkinson in 1817. Each year, 50,000-60,000 people in the United States are diagnosed with the disease. Parkinson\u2019s disease causes the loss of dopamine neurons in the substantia nigra, a midbrain structure that regulates movement. Loss of these neurons causes many symptoms including tremor (shaking of fingers or a limb), slowed movement, speech changes, balance and posture problems, and rigid muscles. The combination of these symptoms often causes a characteristic slow hunched shuffling walk, illustrated in Figure\u00a02. Patients with Parkinson\u2019s disease can also exhibit psychological symptoms, such as dementia or emotional problems.<\/p>\n<div style=\"width: 310px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" id=\"5\" class=\"\" src=\"https:\/\/openstax.org\/resources\/47580c08b6399ca04707aa4eaa051118cd41f37f\" alt=\"Illustration shows a hunched man with stiff arms and a shuffling walk.\" width=\"300\" height=\"317\" data-media-type=\"image\/jpg\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 2. Parkinson\u2019s patients often have a characteristic hunched walk.<\/p>\n<\/div>\n<p>Although some patients have a form of the disease known to be caused by a single mutation, for most patients the exact causes of Parkinson\u2019s disease remain unknown: the disease likely results from a combination of genetic and environmental factors (similar to Alzheimer\u2019s disease). Post-mortem analysis of brains from Parkinson\u2019s patients shows the presence of Lewy bodies\u2014abnormal protein clumps\u2014in dopaminergic neurons. The prevalence of these Lewy bodies often correlates with the severity of the disease.<\/p>\n<p>There is no cure for Parkinson\u2019s disease, and treatment is focused on easing symptoms. One of the most commonly prescribed drugs for Parkinson\u2019s is L-DOPA, which is a chemical that is converted into dopamine by neurons in the brain. This conversion increases the overall level of dopamine neurotransmission and can help compensate for the loss of dopaminergic neurons in the substantia nigra. Other drugs work by inhibiting the enzyme that breaks down dopamine.<\/p>\n<div class=\"textbox tryit\">\n<h3>Try It<\/h3>\n<p>\t<iframe id=\"assessment_practice_fea2e45e-c921-4339-abec-6393f4c8438c\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/fea2e45e-c921-4339-abec-6393f4c8438c?iframe_resize_id=assessment_practice_id_fea2e45e-c921-4339-abec-6393f4c8438c\" frameborder=\"0\" style=\"border:none;width:100%;height:100%;min-height:300px;\"><br \/>\n\t<\/iframe>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-4021\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Biology 2e. <strong>Provided by<\/strong>: OpenStax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\">http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Access for free at https:\/\/openstax.org\/books\/biology-2e\/pages\/1-introduction<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":17,"menu_order":22,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Biology 2e\",\"author\":\"\",\"organization\":\"OpenStax\",\"url\":\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Access for free at https:\/\/openstax.org\/books\/biology-2e\/pages\/1-introduction\"}]","CANDELA_OUTCOMES_GUID":"ac15663b-dbfa-41f2-85c0-a31fa4d564dd, 364c856b-2bfa-43c9-a99d-159bcccb0f4e","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-4021","chapter","type-chapter","status-publish","hentry"],"part":3966,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4021","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/users\/17"}],"version-history":[{"count":10,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4021\/revisions"}],"predecessor-version":[{"id":8520,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4021\/revisions\/8520"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/parts\/3966"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4021\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/media?parent=4021"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapter-type?post=4021"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/contributor?post=4021"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/license?post=4021"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}