When an Alzheimer's Diagnosis May Be Another Dementia
Researchers discover a new memory loss syndrome and identify critical differentiating criteria
Researchers at the Mayo Clinic in Rochester, Minnesota recently published in "Brain Communications" new criteria for a memory-loss syndrome in older adults that mimics Alzheimer's but impacts explicitly the brain's limbic system.
The disorder, Limbic-predominant Amnestic Neurodegenerative Syndrome, or LANS, shares memory loss as one of the early defining symptoms of Alzheimer's; however, researchers discovered through biomarkers and other data that is where the similarities between the two dementias veer off. The limbic system in the forebrain is responsible for emotional and behavioral responses.
"The most important thing for individuals to know is that not all later life memory problems are Alzheimer's."
"There are key differences between LANS and Alzheimer's," said David T. Jones, M.D., a Mayo Clinic neurologist and senior author of the study. "Specifically, LANS progresses at a slower pace, and while it does lead to significant dementia, it's on a much different timeline with a better prognosis."
According to the latest figures, Alzheimer's and other dementias affect more than 55 million people worldwide. In the U.S., nearly seven million Americans are living with Alzheimer's, a disease that robs a person of memory, impacts thinking and behavior, and eventually interferes with the ability to complete tasks on one's own.
In the case of LANS, Jones said, "We see symptoms appear later in life and impact memory alone without the additional cognitive losses. The most important thing for individuals to know is that not all later life memory problems are Alzheimer's."
How the Study Began
"This has been an evolving body of work, built on decades of research from across the world," Jones explained to Next Avenue via Zoom. As a practicing clinician specializing in cognitive disorders, Jones frequently works with patients complaining of memory loss without exhibiting other signs of cognitive decline.
For example, Jones said individuals often find their way to his office through a general practitioner after having been diagnosed with Alzheimer's based on the patient's (or a family member's) assessment of the severity of their memory skills and possibly abnormal brain scans.
"I would probe further with new biomarker testing available for tau and amyloid protein deposits in the brain, characteristic of Alzheimer's, and there would be no evidence of the disease," Jones stated. Without a clear answer, this left the patient and Jones frustrated and still asking, "If it's not Alzheimer's, what is it?"
Before establishing clinical criteria, the only way to distinguish between LANS and Alzheimer's was through autopsies of the brain. Jones recognized early on the power of machine learning and that, combined with pathology, the two could advance understanding.
In addition to clinical work, Jones leads the AI efforts at Mayo Clinic's Department of Neurology. "So, when Mayo started embracing the ability to connect patient data to this technology, I was excited about the potential it offered my patients."
The Criteria Framework
According to a Mayo Clinic press release, "[T]he proposed criteria provide a framework for neurologists and other experts to classify the condition in patients living with symptoms, offering a more precise diagnosis and potential treatments."
Several standards physicians can look for are listed here:
- Generally patients are 75 and older
- Mild syndrome with preserved neocortex functions (no executive or spatial problems)
- A CT scan indicating hippocampi atrophy is small
- Unusual semantic memory problem – difficulty recalling salient (aka “distinctive”) features
Jones described these factors, combined with PET scans, further imaging and the biomarkers mentioned earlier, as all leading to more accurate diagnoses for patients. The press release from the Mayo Clinic quoted Nick Corriveau-Lecavalier, Ph.D., the paper's first author, "[T]hese findings build upon scientists' continued efforts to untangle neurological conditions that often have similar symptoms or can occur simultaneously but can have drastically different treatments and prognoses."
What This Means for Ongoing Alzheimer's Treatment
Rebecca M. Edelmayer, Ph.D., senior director of scientific engagement for the Alzheimer's Association, said via email, "This research exemplifies the great need to develop objective criteria for diagnosis and staging of Alzheimer's and all other types of dementia, and to create an integrated biological and clinical staging scheme that can be used effectively by physicians. Advances in biomarkers will help to differentiate all types of dementia when incorporated into the diagnostic workup, but until those tools are available, a more succinct clinical criteria for diagnosis can be used to support a more personalized medicine approach to treatment, care and enrollment into clinical studies."
"With the condition only recently being defined, we will need to conduct clinical trials to ascertain what drugs and lifestyle changes may help."
While there is no cure for Alzheimer's, The U.S. Food and Drug Administration (FDA) has approved several medications that range from easing symptoms of the disease to reducing the amount of beta-amyloid in the brain.
When asked what this means for people who may have been misdiagnosed with Alzheimer's prior to recent diagnostic advances, Jones replied, "We tell those patients they certainly shouldn't go forward with Alzheimer's therapies such as amyloid-reducing drugs."
He added, "We counsel people on what we think the future will look like; however, with the condition only recently being defined, we will need to conduct clinical trials to ascertain what drugs and lifestyle changes may help."
There continues to be compelling evidence that following healthy diets such as MIND (Mediterranean–DASH Intervention for Neurodegenerative Delay) and Mediterranean diets as well as exercise can either slow down or reduce the risks of mild cognitive impairment and early dementia. Jones suggested individuals become involved in clinical study programs to aid scientists in learning more.
Another option is for people to consider donating their brains to research.
"As scientists better understand the causes of degenerative diseases, we can tailor our therapies to how a specific person's brain changes with age. This knowledge will dramatically increase the difference we make in people's lives in the future," Jones said.
