Limbic-Predominant Amnestic Neurodegenerative Syndrome: A Newly Recognized Memory Condition Distinct from Alzheimer's Disease

Core Concepts

Limbic-predominant amnestic neurodegenerative syndrome (LANS) is a newly recognized memory condition that is distinct from Alzheimer's disease and primarily affects the limbic system, leading to a slow, amnestic, and predominantly neurodegenerative syndrome.

Abstract

The article discusses a newly recognized memory condition called limbic-predominant amnestic neurodegenerative syndrome (LANS), which is distinct from Alzheimer's disease. LANS is characterized by a slow, amnestic, and predominantly neurodegenerative syndrome that primarily affects the limbic system.

The key highlights and insights from the article are:

1. LANS is a different type of neurodegenerative syndrome that progresses slowly, is limited mainly to memory loss, and affects only the limbic system, as opposed to Alzheimer's disease, which involves neocortical degeneration.
2. The clinical criteria for LANS include core features (slow, amnestic, predominant neurodegenerative syndrome), standard supportive features (older age, mild clinical syndrome, hippocampal atrophy out of proportion to syndrome severity, mildly impaired semantic memory), and advanced supportive features (limbic hypometabolism, low likelihood of significant neocortical tau pathology).
3. LANS is highly associated with limbic-predominant, age-related TDP-43 encephalopathy neuropathological change (LATE-NC), for which no biomarkers are yet available.
4. The diagnosis of LANS requires a nuanced assessment of the pattern of cognitive deficits, brain imaging, and disease progression over time, which may involve referral to specialists like behavioral neurologists, geriatricians, or psychiatrists.
5. Primary care physicians can use various cognitive assessments, such as the Montreal Cognitive Assessment (MoCA), to help diagnose dementias and identify potential LANS cases, and should also look for reversible causes of memory complaints.
6. As awareness of LANS increases, the proportion of people diagnosed with this condition may rise, and further research is needed to develop better diagnostic tools and treatments.

Stats

LANS is found in about 40% of autopsied brains in people over the age of 85 years.
A diagnosis of mild cognitive impairment or mild amnestic dementia (i.e., a score of ≤ 4 on the Clinical Dementia Rating Sum of Boxes [CDR-SB]) is a standard supportive feature for LANS.
Hippocampal volume is smaller than expected on MRI compared with the CDR-SB score in LANS patients.

Quotes

"Memory problems are not always Alzheimer's disease. It's important to broaden the differential diagnosis and seek diagnostic clarity and precision for patients who experience problems with brain functioning later in life."
"We are increasingly recognizing that the syndrome of dementia in older adults is heterogeneous."
"It may be that as we start more freely giving the diagnosis of a possible LANS, the proportion of people will go up."

Key Insights Distilled From

Not Alzheimer's: Have You Seen This 'New' Memory Condition?

by Karen at www.medscape.com 08-07-2024

https://www.medscape.com/viewarticle/cognitive-breakdown-new-memory-condition-primary-care-needs-2024a1000egv

Deeper Inquiries

What are the potential underlying etiologies for LANS, other than the known buildup of TDP-43 protein deposits?

Apart from the accumulation of TAR DNA-binding protein 43 (TDP-43) protein deposits, other potential underlying etiologies for Limbic-Predominant Amnestic Neurodegenerative Syndrome (LANS) include various degenerative changes in the limbic system. These changes can be caused by factors such as age-related neurodegeneration, which may lead to atrophy in regions like the amygdala, hippocampus, and middle frontal gyrus. Additionally, LANS can be associated with LATE-NC (Limbic-Predominant, Age-Related TDP-43 Encephalopathy Neuropathological Change), which primarily affects individuals over the age of 85 years and is found in a significant percentage of autopsied brains in this age group.

How can primary care physicians effectively collaborate with specialists to improve the early detection and management of LANS cases?

Primary care physicians can enhance the early detection and management of Limbic-Predominant Amnestic Neurodegenerative Syndrome (LANS) by establishing effective collaborations with specialists such as neurologists, geriatricians, and behavioral neurologists. This collaboration can involve regular communication and sharing of patient information, including cognitive assessments, MRI findings, and fluid biomarker results. Primary care physicians can refer patients showing signs of memory impairment to specialists for further evaluation and diagnosis, especially when considering the nuanced features of LANS that require expertise in neurodegenerative disorders. By working together, primary care physicians and specialists can ensure timely and accurate identification of LANS cases, leading to appropriate management strategies and support for patients.

What are the potential implications of the increasing recognition of LANS on the overall understanding and treatment of age-related neurodegenerative disorders?

The growing recognition of Limbic-Predominant Amnestic Neurodegenerative Syndrome (LANS) has significant implications for the overall understanding and treatment of age-related neurodegenerative disorders. Firstly, it highlights the heterogeneity of dementia syndromes in older adults, emphasizing the need for a comprehensive differential diagnosis approach to address various cognitive deficits. The identification of LANS underscores the importance of early diagnosis and tailored management strategies that consider the specific cognitive and neurodegenerative patterns associated with this syndrome. Furthermore, the recognition of LANS may lead to advancements in diagnostic criteria, prospective studies, and the development of clinical tools to improve the accuracy of diagnosis and monitoring of neurodegenerative disorders. Ultimately, the increasing awareness of LANS can contribute to a more nuanced and personalized approach to the understanding and treatment of age-related cognitive decline, paving the way for targeted interventions and improved outcomes for affected individuals.