which flu risk would you take?
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10 SCIENTIFIC AMERICAN MIND August/September 2006
Seeing Alzheimer’s Early
One of the daunting aspects of Alzheimer’s disease is that it is seldom diagnosed until victims have already lost signifi cant cognitive function. Even if treatments are developed, they will not have sweeping impact unless early-detection methods are devised.
One step toward this grail may come from psychiatrist and brain researcher Eric Reiman of the Banner Alzheimer’s Institute in Phoenix. He has been using positron-emission tomography (PET) to study cognitively healthy people at three levels of genetic risk for the disease—those with two copies, one copy or no copies of the apolipoprotein E type 4 (APOE4) gene, which has been implicated in autopsies of Alzheimer’s victims. Reiman says that APOE4 carriers show reduced metabolism in brain regions known to be affected by Alzheimer’s disease and that “these reductions become more pronounced over time.” He and his colleagues plan to use PET to evaluate high-risk groups as various therapies are undertaken, to try to reveal if a therapy shows any effect. “Our goal is to fi nd an effective way to prevent [Alzheimer’s] without having to lose a generation along the way,” Reiman says.
Scott Small, a neurologist at Columbia University, is using magnetic resonance imaging to defi ne an early-warning clue in the
hippocampus, vital to memory. “By imaging Alzheimer’s patients over time,” he explains, “we have found which parts of the hippo-campus have neuronal dysfunction.” The pattern of dysfunction in Alzheimer’s is different from that in normal aging. “We could use this knowledge both to diagnose [Alzheimer’s] in its earliest stages,” Small says, “and to test new drugs to see if they arrest cell loss in these special regions.” —Jonathan Beard
Which Flu Risk Would You Take?Individuals facing a medical dilemma are more likely to choose a riskier course for themselves than for others.
Researchers at the University of Michigan and the V.A. Ann Arbor Healthcare System asked 2,400 participants in an online study to play one of four roles: a patient deciding on individual treatment, a parent choosing for a child, a physician advising a patient, or a medical director setting guidelines for many patients. The volunteers were then asked to imagine a serious fl u outbreak that presented a 10 percent chance of causing death and were given the option to take a new fl u vaccine that carried a 5 percent chance of being fatal.
People playing the parent, doctor and medical director roles were all more likely to choose the vaccine than those playing the self-treating role. Responses followed a similar trend
when participants were presented with a cancer scenario and the choice to have chemotherapy or not. The outcomes represent the phenomenon of “omission bias”—choosing inaction over action, even at the risk of greater harm.
Study leader Brian J. Zikmund-Fisher, who holds research positions at the university and the V.A., notes that even though actual patients in recent years have become increasingly involved in making treatment choices, the study emphasizes why clinicians should not become less involved. “There remains an important role for coaching the decision-making process,” he says—“helping patients to see the big picture.”
Zikmund-Fisher is planning follow-up work that will examine the effect of perspective on decisions made in end-of-life settings, such as choosing symptom-relieving care versus aggressive treatments that could prolong life but at a lower quality.
—Nicole Garbarini
Patients with Alzheimer’s have progressively reduced metabo-lism in certain locations (blue, at right). Cognitively normal young adults who carry a common Alzheimer’s susceptibility gene already have reduced activity in the same locations (left), more than four decades before typical onset of symptoms.
Young Adults at Genetic Risk Alzheimer’s Disease
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Study subjects playing doctors or parents would give a new fl u vaccine to others—but not to themselves.