Although some progress has been made in the last two decades on the tr

Although some progress has been made in the last two decades on the treatment of Alzheimer’s disease, the causes of the disease are still largely unknown. A recent study conducted by the National Institute of Aging (NIA) appears to have found new evidence concerning the origins of Alzheimer’s. Scientists who carried out the study at NIA focused on the correlation between a patient’s genetic history, which scientists usually agree is the basis of Alzheimer’s, and the onset of Alzheimer’s. The evidence cited by the NIA team includes the identification of the apolipoprotein E (APOE) as the specific gene that may be responsible for the onset of Alzheimer’s. The APOE gene can be sub-divided into many different forms, but the NIA research team has identified one specific form of APOE, the APOE ?4 gene, as a very likely cause of Alzheimer’s. The presence of APOE ?4 is known to make an individual particularly vulnerable to both cognitive and vascular dysfunction, which are among the chief symptoms of Alzheimer’s.

However, a review of the study and its results by the Center for Disease Control and Prevention (CDC) maintains that the evidence discovered by the NIA may not necessarily indicate that the APOE ?4 gene is responsible for Alzheimer’s. CDC experts have pointed out that APOE ?4 is known to cause conditions such as cardiac disease and diabetes in patients who have no genetic history of Alzheimer’s and are not considered at risk for the disease. Further, the CDC review team has observed that APOE ?4 has been found in individuals who show no symptoms of Alzheimer’s. In response to the CDC’s review, the NIA team has pointed out that the APOE ?4 gene may be dormant in some individuals, suggesting that the absence of Alzheimer’s in individuals who have the APOE ?4 gene cannot be used as evidence to rule out this gene as the cause of Alzheimer’s disease.

1. The primary purpose of the passage is to
A. present information that goes against a particular finding about a disease
B. propose further investigation to come to a conclusive result in a dispute about the cause of a disease
C. resolve the controversy about the treatment of a disease
D. evaluate a dispute about whether genetic factors could be the basis of a disease
E. present the findings of a new study and debate over the same



2. The author makes which of the following statements about the relevance of genetic history as the basis of Alzheimer’s disease?
A. The NIA is the first to claim it.
B. It is disputed by the CDC’s expert review team.
C. It is not generally disputed by scientists.
D. It has been challenged by the researchers at NIA.
E. It makes the NIA’s finding unlikely to be correct.



3. Which of the following claims does the NIA support by providing the information that the APOE ?4 gene may be dormant in some individuals?
A. The presence of the APOE ?4 gene and the absence of Alzheimer’s in the same individual does not weaken the claim that the APOE ?4 likely causes Alzheimer’s.
B. Individuals in whom the APOE ?4 gene is dormant are at high risk for Alzheimer’s disease.
C. The fact that individuals with dormant APOE ?4 gene show no sign of Alzheimer’s does not indicate that genetic history is not the basis of the disease.
D. The absence of Alzheimer’s in individuals with the APOE ?4 gene makes it unlikely that APOE ?4 is the cause of Alzheimer’s.
E. The dormancy of the APOE ?4 gene is an indication that this gene may cause cardiac disease and diabetes even when it doesn’t cause Alzheimer’s.




4. Which of the following best describes the function of the first sentence of the second paragraph?
A. It provides evidence to support the claim that the APOE ?4 gene is the likely cause of Alzheimer’s disease.
B. It offers new evidence that contradicts the previously accepted belief that a person’s genetic history is the basis of Alzheimer’s disease.
C. It states a position that does not favor the findings of a study conducted at the National Institute of Aging.
D. It provides an opinion that, if true, could lead to more effective methods of treatment for conditions such as cardiac disease and diabetes.
E. It suggests that methods of data collection used in the study conducted by the National Institute of Aging were flawed.