When Alzheimer’s Disease Is Really Something Else…

Is it Alzheimer’s, or isn’t it? Making a diagnosis isn’t that simple when you’re dealing with the brain, which scientists believe to be the most complicated biological structure in the known universe.

But now Mayo Clinic researchers have made a remarkable discovery: A new type of memory loss that’s easily mistaken for Alzheimer’s disease. Making the distinction is important because the new syndrome progresses slowly and has a better prognosis. Here’s what you need to know…

Key Takeaways

• Mayo Clinic researchers discovered Limbic-Predominant Amnestic Neurodegenerative Syndrome (LANS), a new form of memory loss.
• LANS differs from Alzheimer's because it impacts memory without advancing to other cognitive areas.
• Some people misdiagnosed with Alzheimer’s can now be treated appropriately for LANS.

Understanding LANS

The brain contains around 86 billion neurons, each forming thousands of synaptic connections, resulting in a highly complex network. It’s no surprise that scientists are making discoveries all of the time. One of the most recent happened at The Mayo Clinic.

Scientists at the Mayo Clinic uncovered a new type of memory disorder that's been masquerading as Alzheimer's disease. This discovery could change how we think about aging and memory loss, offering hope to millions of older adults and their families.

It’s called Limbic-Predominant Amnestic Neurodegenerative Syndrome, or LANS for short.

So, What Makes LANS Different From Alzheimer's?

For starters, it typically shows up later in life, usually in people 75 and older.

Unlike Alzheimer’s, which affects broader areas of the brain and involves a buildup of toxic amyloid and tau proteins, the syndrome they discovered affects the limbic system, a collection of brain regions responsible for emotional responses and memory.

The memory loss in LANS is gradual and often doesn't spread to other cognitive areas. This means that people with LANS might forget things, but they're less likely to experience the wide-ranging cognitive decline associated with Alzheimer's. It's like the difference between a slow leak and a burst pipe - both are problems, but one is more manageable!

LANS isn’t the only condition affecting older seniors' limbic system. In 2019, we reported on limbic-predominant age-related TDP-43 encephalopathy (LATE), described by a neuropathologist at the time as “the most striking mimic of Alzheimer's”. TDP-43 is a protein that gets misfolded and accumulates in the hippocampus, a key memory area and part of the limbic system.

Identifying People With LANS

For the new study, the scientific team analyzed the brains of over 200 people from two groups of deceased patients with late-life memory problems as well as looking at medical information on each one when they were alive. From all this data they developed a test to distinguish LANS from Alzheimer’s and LATE.

The findings showed those with a high likelihood of having LANS were also likely to have LATE and have slower cognitive decline. Some also showed signs of brain changes typical of Alzheimer’s, but if LANS were the primary factor, they also experienced slower memory decline.

On the flip side, those with a low likelihood of LANS were much more likely to have Alzheimer’s. In their paper, published in the journal Brain Communications in July, the researchers laid down the clinical criteria for LANS. These included:

• Aged 75 and older.
• Memory loss declines gradually.
• Good preservation of brain structures outside the limbic system.
• A low likelihood of tau buildup.
• Disproportionate weakening, or atrophy, of the hippocampus (part of the limbic system).
• Mildly impaired semantic memory – which is the knowledge accumulated throughout life.
• Low metabolism and energy creation within the limbic system.

One of the researchers explained further...

"Historically, you might see someone in their 80s with memory problems and think they may have Alzheimer's disease, and that is often how it's being thought of today," says Nick Corriveau-Lecavalier, leader of the large team of Mayo Clinic researchers.

"With this paper,” he continues, “we are describing a different syndrome that happens much later in life. Often, the symptoms are restricted to memory and will not progress to impact other cognitive domains, so the prognosis is better than with Alzheimer's disease."

New Hope For Memory Loss Treatment

This discovery is a big deal for several reasons. First, it offers hope to many older adults who might have been misdiagnosed with Alzheimer's. Knowing they have LANS instead could mean a more optimistic outlook and potentially different treatment approaches. It also highlights the importance of accurate diagnosis in memory disorders.

Dr. David Jones, senior author of the study, hopes that making a diagnosis of LANS rather than Alzheimer’s will result in better management of symptoms, more tailored therapies, and improved counseling of patients about the nature of their symptoms.

"In our clinical work, we see patients whose memory symptoms appear to mimic Alzheimer's disease, but when you look at their brain imaging or biomarkers, it's clear they don’t have Alzheimer's. Until now, there has not been a specific medical diagnosis to point to, but now we can offer them some answers.

"This research creates a precise framework that other medical professionals can use to care for their patients. It has major implications for treatment decisions, including amyloid-lowering drugs and new clinical trials, counseling on their prognosis, genetics, and other factors."

Our Takeaway

While memory loss can be scary at any age, this research reminds us that not all forgetfulness is a one-way ticket to severe cognitive decline. LANS might be the silver lining some families have been hoping for in the cloud of memory loss.

And remember, there are other kinds of dementia that also frequently get misdiagnosed. For instance, Frontotemporal Dementia (FTD) is often confused for early-onset Alzheimer’s disease. There’s also Functional Cognitive Disease (FCD), that may affect up to HALF of memory clinic patients. And, an estimated 600,000 Alzheimer’s patients in America may really be suffering from a treatable and reversible condition called Normal Pressure Hydrocephalus (NPH).

 Several other health issues can mimic early dementia. For example, the treatable liver condition hepatic encephalopathy can cause memory problems. So can hidden medical conditions, including anemia, vitamin B deficiencies, and prescription drug side effects. 

As we unravel the mysteries of the aging brain, who knows what other discoveries might be just around the corner? In the meantime, if you or a loved one has been diagnosed with Alzheimer’s or dementia, it's always worth talking to a doctor to re-evaluate your diagnosis.

Summary

Mayo Clinic researchers have identified a new memory disorder, Limbic-Predominant Amnestic Neurodegenerative Syndrome (LANS), which is often mistaken for Alzheimer's disease. Unlike Alzheimer's, LANS primarily affects the limbic system and progresses more slowly, allowing for a better prognosis. Researchers hope this finding will enable more accurate diagnoses, personalized treatments, and improved care for all patients with dementia.

Frequently Asked Questions

What is Limbic-Predominant Amnestic Neurodegenerative Syndrome (LANS)?