â€œA final lesson from the history of bioethics is the consensus that if you can't offer a patient anything to prevent or to ameliorate a terrible disease, why test for it?,â€ writes University of Alabama at Birmingham bioethicist Greg Pence in a heartfelt op/ed in the Birmingham News. Pence is specifically concerned about burgeoning availability of tests for the brain- and personality-destroying horror that is Alzheimerâ€™s disease.
Just last week, an expert panel at the Food and Drug Administration recommended that the agency approve a new test developed by Avid Radiopharmaceuticals that can detect the presence in the brain of plaques of the amyloid protein associated with Alzheimerâ€™s disease. The test uses a radioactive dye that attaches to amyloid plaques. That dye can then be detected with positron emission tomography (PET) scans.
Other researchers are developing a test that measures amyloid and other protein levels in spinal fluid. They recently reported that the test found the protein signature for Alzheimerâ€™s disease in 90 percent of the patients who had already been diagnosed with the disease. In addition, the test found the disease signature in 72 percent of those who have mild cognitive impairment, and in 36 percent of patients who were cognitively normal. Withdrawing spinal fluid is tricky, so researchers at the University of California, San Francisco, are working on a blood test to predict which patients are likely to suffer from Alzheimerâ€™s disease.
Most interestingly in the spinal fluid study, many of the cognitively normal subjects with the Alzheimerâ€™s disease signature carry a version of the apolipoprotein E (APOE4) gene. People with one copy of the APOE4 gene have a three times greater-than-average risk of suffering from the disease. Two copies of the gene confer a 12 times greater than average risk. The researchers noted, â€œThe unexpected presence of the [Alzheimer's disease] signature in more than one-third of cognitively normal subjects suggests that [Alzheimer's disease] pathology is active and detectable earlier than has heretofore been envisioned.â€ In other words, the test can identify people years in advance who are likely to eventually suffer from the disease.
Several direct-to-consumer gene testing companies now include an APOE gene test. People with the rare APOE2 version seem to be protected against the disease while those with the APOE3 version have an average risk of coming down with it. The lifetime risk of Alzheimerâ€™s disease among those who reach the age of 65 is approximately one in five for women and one in 10 among men. Clearly, the direct-to-consumer gene testing companies are ignoring Penceâ€™s bioethical â€œconsensusâ€ about offering tests for incurable diseases.
Why are so many bioethicists against such testing? Chiefly, they fear that bad news will provoke anxiety in people whose lives would be forever deformed by dread of impending mental doom. But is that so? A 2009 study found that subjects who were told their APOE gene status did not suffer any greater levels of anxiety than people who did not know what version of the APOE gene they carry. â€œThe disclosure of APOE genotyping results to adult children of patients with Alzheimer's disease did not result in significant short-term psychological risks,â€ researchers concluded.
This result has now been bolstered by another study published online on January 12, 2011 in the New England Journal of Medicine. Eric Topol, a professor of translational genomics and his colleagues at the Scripps Translational Science Institute in La Jolla, California, recruited 3,600 people to take a genotype screening test from Navigenics. The test looks for gene variants that affect risks for 23 different diseases including breast cancer, colon cancer, heart attack, diabetes, and the APOE gene variants. The researchers then monitored the participants to find out if the genetic risk information increased their anxiety or encouraged them to change their health habits. The researchers reported, â€œWe found no short-term changes in psychological health, diet and exercise behavior, or use of screening tests.â€ The test results triggered no dark existential anxieties; people basically just carried on with their lives.
Weâ€™ve experienced this kind of bioethical condescension before. In 1998, a panel of eminent bioethicists convened at Stanford University advised that most women should not take the new test for the BRCA-1 and BRCA-2 breast cancer genes. As Boston University bioethicist George Annas familiarly explained, "Since there is no way to prevent this disease, what good is knowing you will probably get it in the future?" In addition, the bioethicists worried, â€œWomen who undergo genetic testing may face psychological problems in adjusting to the results, whether positive or negative.â€ Poor dears, they will just be driven to distraction by the newfangled test results. But once again, bioethical fears about the psychological fragility of consumers turned out to be just wrong. A 2008 study found that women four years after taking the BRCA test had suffered no adverse psychological consequences from it.
The National Cancer Institute estimates lifetime risk for breast cancer in women with BRCA-1 or BRCA-2 mutations at about 60 percent and estimates their ovarian cancer risk ranges from 15 percent to 40 percent. Keep in mind that the average lifetime risk for breast cancer is about 12 percent. Fifteen years later, the American Civil Liberties Union (ACLU) is asserting that not only should access to BRCA testing not be restricted, but that it is a womanâ€™s right to get tested. â€œIndividual patients' rights are violated because gene patents impede access to medical information and care,â€ argues the ACLU in its lawsuit against the Myriad Genetics, the company that has the patent rights to the test. What was once restricted has become a right. In a few more years, the same will become true for Alzheimerâ€™s disease testing too.
There are lots of different answers to Penceâ€™s question, why test for incurable diseases like Alzheimerâ€™s disease? Now that the tests are becoming available, researchers can identify people who are at higher risk of falling ill earlier, and enroll them in studies to uncover how the disease progresses. This will also allow scientists to enroll subjects in clinical trials earlier for new drugs aimed at preventing the disease.
Testing is not just about therapy. People can also use the information to help plan their futures. Perhaps they will drop out of the corporate grind and become Caribbean sailing captains. Or they will arrange their affairs so that they can receive good care when they do fall ill. Of course, some people really may not want to know. In which case, they are perfectly free to not take the tests. The only people who seem especially overwrought and unable to handle the results of genetic testing are bioethicists.
Disclosure: According to my results from Pathway Genomics, I am homozygous for APOE3 which suggests that my risks for coming down with Alzheimerâ€™s disease is average, at least with respect to this risk factor. For more details on genetic testing and why concerns over genetic privacy are exaggerated see my article, â€œIâ€™ll Show You My Genome. Will You Show Me Yours?â€
Ronald Bailey is Reason's science correspondent and author of Liberation Biology: The Scientific and Moral Case for the Biotech Revolution (Prometheus Books).