7.3.3 Alzheimer’s Disease
Alzheimer’s disease（AD）is a progressive disease accounting for 60%to 80%of cases of dementia，which causes the loss of cognitive functioning（thinking，remembering and reasoning）and behavioral abilities to such an extent that it interferes with a person’s daily life and activities（Fig.7-7）.
Fig.7-7 Progression of Alzheimer’s Disease
Scientists believe that AD results from unexplained degeneration of neurons and atrophy of the cerebral cortex，which can be diagnosed by CT or MRI scan and confirmed at autopsy.Two abnormal structures called plaques and tangles are prime suspects in damaging and killing neurons.Although autopsy studies show that most people develop some plaques（deposits of a protein fragment called beta-amyloid that build up in the spaces between nerve cells）and tangles（twisted fibers of another protein called tau that build up inside cells）as they age，those with AD tend to develop far more and in a predictable pattern，beginning in the areas important for memory before spreading to other regions.And patients with Down syndrome commonly develop AD after age 40，indicating that AD is associated with an abnormality on chromosome 21.A clinical diagnosis of AD is based on tests such as physical，psychological，neurological and psychiatric examinations accompanied by various laboratory tests.With today’s new diagnostic tools and criteria，it is possible for physicians to make a positive clinical diagnosis of AD with approximately 90%accuracy.
Treatment for AD includes the use of tacrine hydrochloride（Cognex），which is used in mild to moderate cases due to its ability to improve memory in approximately 40%of patients with AD.Antidepressants and tranquilizers are also frequently used to treat symptoms.The persons/families experiencing AD need a great deal of education and support to endure this difficult disease.
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Task 5 Fill in the blanks with proper words.
1.________is a progressive disease resulting from unexplained degeneration of neurons and atrophy of the cerebral cortex.
2.Patients with________have mental deterioration of organic or functional origin.(https://www.daowen.com)
3.Deposits of a protein fragment that build up in the spaces between nerve cells are referred to as________.
4.Alzheimer’s disease as the most common cause of dementia among the elderly is characterized by plaques and________in the brain.
5.Degeneration of neurons and________of the cerebral cortex are the common causes for Alzheimer’s disease.
6.________refers to a group of symptoms that occurs together in a disease or disorder.
7.Alzheimer’s disease is considered to be associated with________on chromosome 21.
8.Clinical diagnosis relying primarily on cognitive tests can reach 70%to 90%________in late stages of Alzheimer’s Disease.
9.________is a chromosomal condition that is associated with intellectual disability，a characteristic facial appearance，and weak muscle tone in infancy.
10.________are medications used to treat major depressive disorder，anxiety disorders，and chronic pain conditions.