Semantic intrusion for more practical detection
Semantic and then imaging, this innovative strategy developed at the University of Miami is promising for earlier detection of Alzheimer's disease. The team exploits "semantic intrusion" to identify amyloid positivity in mild cognitive impairment, and thus provides a new option in the search for an effective way to identify patients at high risk of Alzheimer's.
What is it about ?
From a scale, developed at the university, the Loewenstein-Acevedo Scales for Semantic Interference and Learning or LASSI-L. Lead author Dr. David Loewenstein, director of the Center for Cognitive Neuroscience and professor of psychiatry explains that this scale helped identify specific memory deficits in study participants that align with the results. brain scan imaging (see visual) showing abnormal buildup of amyloid in the brain.
The study is conducted in 88 patients with amnesic mild cognitive impairment. In this group of patients, the team managed to identify 34 people with underlying Alzheimer's disease (AD), with scans positive for amyloid. Among the 54 participants negative for beta amyloid, 29 are then suspected, thanks to the test, as having a clinical course suggestive of Alzheimer's disease but without certainty. The remaining 25 amyloid-negative patients have major depression, anxiety, or other psychiatric disorders or brain damage.
On the LASSI-L scale:
It allows researchers to detect patients at greatest risk of Alzheimer's disease. Imaging results showing in these same patients the abnormal accumulation of amyloid in the brain, confirming the test results. This LASSI-L “measure” is in fact a new “cognitive stress test”, now validated in English and Spanish. Patients are asked to read 15 words. The words come from 3 categories, fruits, musical instruments and clothes. Each category has 5 words. Participants should repeat the list of words, then indicate their recall by category. Then the participants receive a new list of 15 different words belonging to the same 3 categories. Patients are asked to recall these new words as a measure of proactive semantic interference (PSI), a phenomenon characterized by interference between new learning based on prior learning but also documented to be correlated with the risk of developing Alzheimer's disease. The searchers also present the second list of words a second time and repeat the indicated recall. This component of LASSI-L measures people's ability to overcome these proactive semantic interferences. This is called ISP recovery failure, a second indicator of MA risk. The searchers also present the second list of words a second time and repeat the indicated recall. This component of LASSI-L measures people's ability to overcome these proactive semantic interferences. This is called ISP recovery failure, a second indicator of MA risk. The searchers also present the second list of words a second time and repeat the indicated recall. This component of LASSI-L measures people's ability to overcome these proactive semantic interferences. This is called ISP recovery failure, a second indicator of MA risk.
Here, the researchers provide the first results of the effectiveness of this relatively simple test since it is based on 2 lists of 5 words. According to this study, the scale would indeed make it possible to detect the first cognitive changes announcing Alzheimer's disease. Indeed, the patients positive for “beta-amyloid” imaging were also those committing a significantly higher number of semantic intrusion errors. Thus, the association of the LASSI-L test with imaging examination seems very promising in the clinical evaluation of preclinical Alzheimer's disease.
Further studies are underway to compare LASSI-L progression to brain biomarkers via MRI, fMRI, and PET.
Is semantic dementia the same as PPA?
SvPPA is also referred to as “semantic dementia” (SD). This is a fluent variant of PPA associated with frontotemporal lobar degeneration (FTLD). The hallmark of svPPA is impaired performance on measures that depend on intact semantics.
What factors affect semantic memory?
The left inferior prefrontal cortex (PFC) and the left posterior temporal areas are other areas involved in semantic memory use. Temporal lobe damage affecting the lateral and medial cortexes have been related to semantic impairments. Damage to different areas of the brain affect semantic memory differently.
What is damaged in semantic dementia?
Semantic dementia (SD) is a neurodegenerative disorder characterized by the progressive loss of semantic memory and conceptual knowledge, coupled with asymmetric local brain atrophy concentrated in the anterior temporal lobe.
What part of the brain controls semantic memory?
The role of the inferior parietal cortex. The inferior parietal cortex lies at a confluence of visual, spatial, somatosensory and auditory processing streams. Human functional imaging studies implicate this region specifically in representational aspects of semantic memory.
How do you measure semantic memory?
Semantic memory is commonly assessed in standard neuropsychological evaluations by verbal fluency with category cues, such as supermarket items or animals, confrontation naming with the Boston Naming Test (Kaplan, Goodglass, & Weintraub, 2001), and the Vocabulary subtest of the WAIS-III (Wechsler, 1997).
What are the 5 words memory test?
Introduction: The five-word test (5WT) is a serial verbal memory test with semantic cuing. It is proposed to rapidly evaluate memory of aging people and has previously shown its sensitivity and its specificity in identifying patients with AD.
What are the 3 words on a memory test?
Recall of Three Little Words Helps Quick Diagnosis of Mild Cognitive Impairment. ATLANTA, Nov. 19 -- Mild cognitive impairment can be determined in less than five minutes with a three-word memory test and a clock-drawing task, according to researchers here. The words are apple, penny, and table.
Why is Alzheimer's testing not recommended?
The Alzheimer's Association doesn't recommend these tests because they don't provide an adequate assessment risk. Even getting a brain scan to look for the clumps of protein known as amyloid plaques that are characteristic of Alzheimer's disease can't accurately predict a future diagnosis.
What are the two main biomarkers of Alzheimer's disease?
The most widely used CSF biomarkers for Alzheimer's disease measure beta-amyloid 42 (the major component of amyloid plaques in the brain), tau, and phospho-tau (major components of tau tangles in the brain, which are another hallmark of Alzheimer's).
What is an example of a semantic memory?
Semantic memory is the memory of acquired knowledge—memorized facts or information. An example of semantic memory would be remembering the capital of Cuba. Semantic memories don't require context, making them objective. Like episodic memories, semantic memories are also explicit and require conscious recall.
What are semantic memory tests?
The SEMEP (SEMantic-Episodic) memory test proposes to assess conjointly semantic and episodic knowledge across multiple tasks: semantic matching, naming, free recall, and recognition.
What is an example of semantic memory loss?
An example of a case study of transient semantic amnesia involves a patient who was admitted into hospital with an acute loss of memory for common words and their meanings. For example, he was unable to understand and differentiate between a "car" and an "engine".
What is the difference between semantic and logopenic dementia?
People with logopenic variant PPA (lvPPA, also known as PPA-L) have difficulty finding words when they are speaking. As a result, they may speak slowly and hesitate frequently as they search for the right word. Unlike people with semantic variant PPA, however, they are still able to recall the meanings of words.
What part of the brain is damaged in semantic dementia?
Semantic dementia, also called progressive fluent aphasia, results when FTD primarily affects the anterior inferior temporal lobe.
What is the difference between semantic dementia and Alzheimer's?
Alzheimer's disease is related to semantic dementia, which both have similar symptoms. The main difference between the two being that Alzheimer's is categorized by atrophy to both sides of the brain while semantic dementia is categorized by loss of brain tissue in the front portion of the left temporal lobe.
What is the most accurate diagnostic tool for Alzheimer's disease?
Brain imaging
A standard medical workup for Alzheimer's disease often includes structural imaging with magnetic resonance imaging (MRI) or computed tomography (CT). These tests are primarily used to rule out other conditions that may cause symptoms similar to Alzheimer's but require different treatment.
What is the most reliable test to diagnose Alzheimer's disease?
Perform brain scans, such as computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET), to support an Alzheimer's diagnosis or rule out other possible causes for symptoms.
What are the three biomarkers in CSF that can be helpful in the diagnosis of Alzheimer's disease?
Thus far, three CSF biomarkers, Aβ42, total-tau (t-tau), and phosphorylated-tau (p-tau), have been found to have the highest diagnostic potential. Biomarkers of inflammation and oxidative stress and urine-based biomarkers are among the other sources that provide vital information on development and progression of AD.
What is semantic dementia ?
A cohort study of diagnostic features and clinical boundaries?
Semantic dementia (SD) designates a progressive cognitive and language deficit, primarily involving comprehension of words and related semantic processing. These patients lose the meaning of words, usually nouns, but retain fluency, phonology, and syntax.
What is semantic memory loss in Alzheimer's disease?
Semantic memory is at first impaired in the language of AD patients, affecting verbal fluency and naming. Semantic loss in AD may occur several years prior to diagnosis. The hippocampus is essential to the consolidation of information from short-term to long-term memory.
