“All screening programs do harm because you'd never have a test that is fully accurate, 100 percent accurate,” Dr. Brayne said. “So inevitably there is misdiagnosis. Some people will be diagnosed and will not have the disorder but will experience potential harms including anxiety and overtreatment, and others will not be diagnosed who do. These things are never perfect.”
Another analysis from the same group had found a dearth of evidence to show that population screenings for cognitive impairment have a significant benefit on clinical or psychosocial outcomes. [See the Neurology Today article, “Does the Evidence Support the Benefits of Population Screenings for Dementia? Not So Much, New Analysis Reveals:” http://bit.ly/18Yu6Ia.]
Malaz Boustani, MD, MPH, who is the director of the Healthy Aging Brain Center in Indianapolis and has studied this topic for about 10 years, said he once thought that dementia screening had to be intrinsically beneficial, but his work has found that the question remains unanswered. He has also been a co-author with Dr. Brayne on several other studies, but was not involved in the current review of population-based screening.
“I was one of the people early on in my career who thought it's obvious that early detection of dementia is a good idea — you don't need science, you don't need evidence to back that up,” he said. “So one of my early mentors told me, ‘OK, just try to study and see what happens if you actually do screening.’ And what I have discovered in the real world, all that perception that I had is not backed up by evidence.”
One problem is that while most patients — some 90 percent, he's found — are agreeable to initial screening, many balk when it's found that they show signs of possible dementia, and refuse to undergo diagnostic testing.
“When we tried to find why, we noticed a lot of them were concerned about the stigma of dementia, so when it was theoretical...they had no hesitation of undergoing the screening,” Dr. Boustani said. “When the screening becomes positive and becomes real, then a lot of them, 50 percent of them, refused (the diagnostic evaluation).”
The larger the number screened, and the wider the net cast, the more potential harm that can be done, he said. “One percent is low if you're dealing just with 100 people, but 1 percent if you're dealing with a million is a lot of people,” he said.
He is now recruiting patients for a randomized controlled trial on the benefits, harms and costs of screening. “We will find out after one year if the benefits of screening outweigh the harms in comparison to the group who did not undergo dementia screening,” he said.
The costs are a crucial consideration in whether to proceed with population-based screening, he said, because the care for currently diagnosed dementia patients has been found to be poor in many instances.
Rachelle Doody, MD, PhD, director of the Alzheimer's Disease and Memory Disorders Center at the Baylor College of Medicine, cautioned that since details on the data on the systematic review had not yet been published, it was difficult to draw helpful conclusions from it.
That concern notwithstanding, she contends that screening should be reconceived. “There should be multiple levels of screening that occur within medical settings and are individualized to a person's risk. That's what I think screening should be, and I think it should occur.”
“As for some kind of screening that takes place in a random geographical area without regard to a person's medical status,” Dr. Doody added, “I don't see how that could be very valuable.”
More work needs to be done on the parameters that are the most valuable for dementia screening, she said.
“When you're talking about individualized personal screening or screening within a medical practice, I think it's very clear that we need it,” she said. “The question is, who should be screened, how much should you screen? Those details we don't have a good evidence base for.”
She said the potential harms should not be a major concern if screening is done properly. “With a rational screening approach, I don't think that people have a tremendous anxiety,” Dr. Doody said.
As far as cost, she said, “If it's worked into a medical practice, resources are not large.”
LINK UP FOR MORE INFORMATION:
•. Fox C, Lafortune L, Boustani M, et al. Screening for dementia - Is it a no brainer. Int J Clin Pract
2013; E-pub 2013 Aug. 16.
© 2013 American Academy of Neurology
•. Stephan BC, Kurth T, Matthews FE, et al. Dementia risk prediction in the population: are screening models. accurate. Nat Rev Neurol
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