As you get older, every time you misplace your wallet or can't remember why you walked into the kitchen, you may wonder: Is this a sign of dementia? Even if such bouts of forgetfulness aren't serious, a screening test for dementia or its most common cause -- Alzheimer's disease -- might seem appealing, if only to reassure you that you're not losing your mind.
Yet there are good reasons to think twice about such a test, says Des Spence, a general physician in Glasgow, Scotland, and a columnist for BMJ. For one thing, early dementia is difficult to distinguish from mild cognitive impairment, those minor memory blips that sneak up as we age. About one in five people older than 75 have such blips, and most cases never progress to dementia or Alzheimer's, Spence says.
Some memory lapses that may seem like dementia are actually something else. In a study published last year, Danish researchers revisited the records of nearly 900 patients thought to have dementia and discovered that 41 percent of them had received faulty diagnoses. Alcohol abuse and depression were the most common problems mistaken for dementia, says study author Lise Cronberg Salem, a neurologist at the Danish Dementia Research Center in Copenhagen.
Small strokes that damage arteries in the brain can cause a type of memory loss known as vascular dementia, and then there's Alzheimer's disease. Right now, an autopsy is the only definitive test for either of these conditions. A recently developed test that uses a PET scan is promising, but "the results can be misleading," according to a statement by the Society for Nuclear Medicine and Molecular Imaging. "The scan does not prove that you have Alzheimer's."
If you're worried about memory loss, your first step should be to see a gerontologist or neurologist who specializes in dementia, not seek a brain scan, says Satoshi Minoshima, a professor of radiology at the University of Washington.
An Alzheimer's diagnosis is made based on tests that evaluate such factors as memory, judgment and orientation to time and place, says Beth Kallmyer, vice president of constituent services at the Alzheimer's Association, a nonprofit based in Chicago. "When a full evaluation is done by somebody who understands how to do it, you're talking 90 percent or so degree of accuracy," Kallmyer says. Such an evaluation goes deeper than the brief memory or recall tests that might be used as a first screen for dementia.
Doctors are required to check Medicare patients for cognitive impairment during the annual wellness visits provided under the Affordable Care Act, and that worries Malaz Boustani, a geriatrician and chief innovation and implementation officer at Indiana University Health. Most of this screening is done with a brief questionnaire or by asking family members to answer questions about their loved one, but there's no one standard test nor is there guidance about what should come next, he says. "I'm nervous that screening alone, without any comprehensive follow-up program, might cause more harm than benefits," Boustani says.
Even with the best screening tests, about 20 percent of those who turn up positive for dementia don't actually have it, and "that's a lot of people walking around worried that they might have dementia, when they don't," Boustani says. Another 30 percent of people who screen positive for dementia actually have only mild cognitive impairment, which won't progress or cause them serious problems.
At the same time, there's evidence that dementia is underdiagnosed in people who have it, says Albert Siu, co-vice chairman of the U.S. Preventive Services Task Force panel that recently evaluated all the research on cognitive impairment screening.
Whether early diagnosis improves outcomes is another open question. The task force found no evidence that early detection helps patients, their caregivers and doctors make better decisions about health care and end-of-life decisions, and it concluded that there simply isn't good evidence to say that clinicians should screen people without symptoms. The task force's statement is not a recommendation not to screen, he says; rather, it's an acknowledgment that it's not clear how the risks and benefits of screening stack up.
Before we start screening more aggressively for dementia and Alzheimer's, we should give careful thought to the implications a diagnosis will have on people's lives, says Michael Gusmano, a bioethicist at the Hastings Center, a research center in Garrison, N.Y. Knowing that your mind is slipping could have consequences for everything from career choices to how you handle your money and whether you can get long-term-care insurance. Gusmano stops short of suggesting that screening shouldn't be available, but he says it shouldn't be offered without a full understanding of the profound effects that the results might have.
Right now, doctors have very few treatments for patients with dementia, and the treatments that are available provide, at best, only modest benefits, Spence says. "Knowing early may just mean that you take away people's sense of well-being earlier," he says. "The idea that you are going to lose your personality and lose who you are -- that's a terrifying prospect, and we need to be very careful about getting that wrong."
If you're experiencing memory problems that interfere with your daily life or if a loved one has noticed marked changes in your cognitive abilities, then it's time for a full assessment, Boustani says. But if your worst memory problem is a forgotten name or a word stuck on the tip of your tongue, there's no compelling reason to seek screening.