Many with mild cognitive impairment missed in screening
by Bradley J. Fikes for The San Diego Union-Tribune:
In a finding with potentially big significance for combating age-related dementia such as Alzheimer’s disease, a study by UC San Diego and VA San Diego scientists has found a disturbingly high percentage of those with mild impairments in thinking are not being detected by routine tests.
But more extensive testing with existing diagnostic methods can improve accuracy, the study said.
Conventional screening misses 7.1 percent of those with mild cognitive impairment – a risk factor for Alzheimer’s and other dementias – the scientists found.
A false negative diagnosis means that people who could benefit from therapy may not be identified early, when treatment has the greatest chance of success, said UCSD’s Emily Edmonds, a study author. And combined with results from earlier research that found false positive rates above 30 percent, the study indicates there’s a great need for more precise testing, she said.
Testing inaccuracies also mean that people chosen for clinical trials of anti-dementia drugs may not fit their presumed category. This is of great importance in testing drugs for Alzheimer’s, for which there is no cure or even a treatment to arrest the disease. Some interventions appear to be helpful in reducing cognitive loss from Alzheimer’s, but they are the most effective when given as early as possible.
The study was published Monday in the Journal of Alzheimer’s Disease. It can be found at http://j.mp/cogtesting. Edmonds was first author. Mark Bondi, of UCSD and the VA, was senior author.
Using data from the Alzheimer’s Disease Neuroimaging Initiative, the scientists compared routine screenings with results from more extensive and precise thinking tests. These tests examine such abilities as being able to describe the characteristics of animals, or deduce objects depicted by line drawings.
Alzheimer’s is the best-known example of cognitive decline. But there are many other causes of impaired thinking, Edmonds said. These can include reduction to blood flow because of stroke or partial blockages of smaller blood vessels in the brain. And in many cases, both conditions are at work, she said. So restoring proper blood circulation could help those who have or are developing Alzheimer’s.
Alzheimer’s is the sixth leading cause of death in the United States, killing 93,541 in 2014, according to the Centers for Disease Control and Prevention. In California, it’s the fifth leading cause of death. And in San Diego County, it’s the third leading cause of death, according to the Alzheimer’s Project, an initiative established by the county in 2014 to combat the disease. More than 62,000 San Diegans are now living with Alzheimer’s or other dementias.
While the numbers are bad enough now, the ranks of Americans with Alzheimer’s is expected to climb sharply in coming decades if present trends continue, according to a 2013 study in the journal Neurology.
From 4.7 million aged 65 and older with Alzheimer’s dementia in 2010, by 2050 13.8 million are projected to have the disease, the study said. Of those, 7 million are expected to be 85 and older. Also growing will be the financial burden, and the psychological burden on the patients and their family members.
To detect people at risk of developing dementia, brief screenings that may take just five minutes are the norm. The more extensive tests take about half an hour, Edmonds said. That requires a considerably greater investment of time. In their favor, these tests have been around for a considerable time and don’t require expensive new technology, she said.
One problem is that the information from these more extensive tests isn’t being used to the fullest extent desirable.
“In large-scale research studies of MCI, participants are often given these tests, but they’re not always taken into account in the diagnosis,” Edmonds said. “It’s really rich, valuable information that’s often already there and available, but has yet to be consistently incorporated into the diagnosis.”
The study provides valuable information to help research and ultimately patients, said Dr. Michael Lobatz, a Scripps Health neurologist who treats patients with memory disorders.
“When you have a diagnosis that suggests you may be heading to a problem, you have the opportunity for better decision-making, for yourself and for your family,” Lobatz said. “You get better medical care as a result.
"The paper indicates that by being able to talk to these patients about the fact that they do have mild cognitive impairment and that there is a risk of going on to developing more profound impairment such as Alzheimer’s disease, that those patients could participate in cognitive therapy. And if they don’t know that, they don’t get that opportunity.”