Is Screening for Pre-dementia a Good Idea?

Does screening for minor memory changes wrongly label persons with dementia? Yes, say some experts, who worry there is not enough good evidence yet to screen for pre-dementia.

Minor memory changes, often called pre-dementia or mild cognitive impairment (MCI), are arguably an inevitable consequence of aging. Although up to 15% of those with MCI will progress to dementia each year, more than half of them will not progress. Many in whom dementia develops do not meet definitions of MCI before diagnosis.

Pre-dementia was included in a new set of diagnostic guidelines for Alzheimer disease issued in May 2011 by 3 consensus groups organized by the National Institute on Aging and the Alzheimer’s Association. For the first time, the guidelines included biomarkers-such as functional MRI, FDG-PET, amyloid imaging, and cerebrospinal fluid analysis-specifically for MCI and preclinical phases of the disease.

“The people with preclinical Alzheimer disease have at most mild impairments in their cognition. They span a spectrum defined at one end as being cognitively normal to, at the other end, needing more time to do their usual, everyday tasks-and even unable to do some of life’s harder tasks, like tax preparation-but they’re not demented,” said Jason Karlawish, MD, Professor of Medicine and Medical Ethics and Health Policy at the Perelman School of Medicine at the University of Pennsylvania.

Dr Karlawish led a recent survey of Alzheimer researchers who agreed that amyloid test results could be released to research participants, if guidance and counseling were put in place.

“For a person with MCI, the benefits of learning amyloid imaging results include an accurate diagnosis of the cause of cognitive impairment,” said Dr Karlawish. “This, in turn, can motivate a person to adopt brain-healthy behaviors, trimming a medication list that often includes a host of symptomatic medications for anxiety and depression and cognitive impairment, and planning for the future.”

However, Dr Karlawish thinks that the concept of preclinical Alzheimer disease is not yet ready for practice. “It remains a diagnosis in the shadows between research and clinical care,” he said. “For now, someone who is labeled being amyloid positive can enroll in a clinical trial to test a drug that targets brain amyloid.”

One such trial will start later this year. The Anti-Amyloid in Asymptomatic Alzheimer’s disease Study will assign 1000 cognitively normal, amyloid imaging-positive, older adults to a drug that clears amyloid or a placebo.
 
Screening for Minor Memory Changes

The drive to screen older persons for minor memory changes is leading to unnecessary investigation and potentially harmful treatment, according to experts from around the world who gathered at the recent “Preventing Overdiagnosis” conference in New Hampshire.

A team of specialists from Australia and the United Kingdom said that an expansion of the diagnosis of dementia will end up including up to two-thirds of persons older than 80 years and up to one-fourth of nondemented older persons being labeled with dementia.

With no drugs available to prevent the progression of dementia or to treat MCI, once patients are labeled, they may be vulnerable to untested therapies, say the specialists.

Perhaps our aging population has become a commercial opportunity to develop screening, early diagnostic tests, and medicines marketed to maintain cognition for a condition that is just part of the normal aging process.