A type of memory loss with aging that was previously unknown

Scientists have identified and defined a type of memory loss in older people that has been confused with Alzheimer’s disease because it has very similar symptoms, but which is a different, more treatable disease.

The research was carried out by scientists at the Mayo Clinic in the United States.

The team has established new criteria for this syndrome of memory loss in older people, which specifically affects the brain’s limbic system. Unlike Alzheimer’s disease, with which it can be confused, limbic-dominant amnestic neurodegenerative syndrome, or LANS, progresses more slowly, has a better prognosis, and is now more clearly defined, all of which will help provide better medical treatment for these patients.

Before researchers developed the clinical criteria, just published in the journal Brain Communications, the features of the syndrome could only be confirmed by examining brain tissue after a person’s death. The proposed criteria provide a set of guidelines for neurologists and other specialists to classify the condition in patients living with symptoms, offering a more accurate diagnosis and possible treatments. They consider factors such as age, the severity of memory impairment, what’s shown on brain scans, and biomarkers that indicate specific protein deposits in the brain.

The criteria were developed and validated using data from more than 200 participants in databases from the Mayo Clinic Alzheimer’s Disease Research Center, a large Mayo Clinic study of aging, and the Alzheimer’s Disease Neuroimaging Initiative.

With the new clinical criteria, it will be easier to mitigate symptoms and offer more personalized therapies for patients suffering from this type of cognitive impairment, as opposed to Alzheimer’s disease, explains Dr. David T. Jones, a neurologist at the Mayo Clinic and co-author of the study.

Artist’s impression of neurons handling a memory of a place. (Image: Amazings / NCYT)

“In our clinical work, we see patients whose memory symptoms appear to be consistent with Alzheimer’s disease, but when we look closely at their brain imaging or biomarkers, it’s clear that they don’t have Alzheimer’s. To date, there hasn’t been a specific medical diagnosis that points to this; but now we can offer patients some answers,” says Jones. “This research creates a precise set of guidelines that other medical professionals can use to treat their patients. This set has important implications for treatment decisions, including amyloid-lowering drugs, new clinical trials, and counseling about a patient’s prognosis, genetics, and other factors.”

Decades of work to understand and classify different types of dementia are ongoing, said Nick Corriveau-Lecavalier, co-author of the study. These findings build on scientists’ ongoing efforts to unravel neurological conditions that often have similar symptoms or can occur simultaneously, but may have drastically different treatments and prognoses.

“Historically, it’s been typical to see someone in their 80s with memory problems and think that person may have Alzheimer’s disease. Many people still think that way these days,” Corriveau-Lecavalier explains. “With this study, we’re describing a different syndrome that occurs much later in life. Often, symptoms are limited to memory and don’t progress or impact other cognitive areas, so the prognosis is better than for Alzheimer’s disease.”

With no signs of Alzheimer’s disease, the researchers looked at the involvement of a possible culprit: a buildup of a protein called TDP-43 in the limbic system that the scientists found in autopsied brain tissue from the elderly. The researchers classified the buildup of these protein deposits as limbic-dominant age-related TDP-43 encephalopathy, or LATE. These protein deposits may be associated with the newly defined memory loss syndrome, but other causes are also likely and more research is needed, the study authors caution.

The study, published in the journal Brain Communications, is titled “Clinical criteria for a limbic-predominant amnestic neurodegenerative syndrome.” (Source: Mayo Clinic)