AI
Sunday, August 04, 2024 11:53:17 AM
The Stages of Dementia scale and CDR-G (which is derived from CDR-SOB) are different rating systems, the Stages being more descriptive and CDR more objective (and hence the one used in studies). Therefore, there is no 100% mapping from one to another. Mild Cognitive impairment has always been difficult to definitely diagnose because of cognitive variability due to intelligence, education, life experience, comorbidities and its overlap with normal aging. MCI was often called questionable or prodromal dementia before mild cognitive impairment became ingrained.
The CDR global scale based on cognitive, activities and social functioning is 0 (Normal); 0.5 (in different references: questionable dementia, very mild dementia or MCI); 1.0 (Mild dementia) ,2.0 (moderate),3.0 (severe).
The FDA in the 2024 guidance clearly links most MCI patients (CDR 0.5) to Stage 3 with this: "Stage 3: Patients with characteristic pathophysiological changes of AD, generally more apparent detectable abnormalities on sensitive neuropsychological measures, and mild but detectable functional impairment. The functional impairment in this stage is not severe enough to warrant a diagnosis of overt dementia. This stage roughly corresponds with the syndrome of “mild cognitive impairment”; however, it is noted that the term “mild cognitive impairment” may also encompass patients in late Stage 2 or early Stage 4." Some CDR 0.5 patients might be 2 and some might be 4 but majority will be Stage 3.
I know some people think I post FUD but they believe everything from Dr. Sabbagh. He links MCI to FDA Stage 3 in this article
https://pubmed.ncbi.nlm.nih.gov/34101796/
The 5 stages in this chart map to CDR 0, 0.5, 1.0, 2.0, 3.0
So knowledgeable neurologists consider MCI to mostly map to FDA Stage 3. Therefore most patients in the trial were FDA Stage 3 and 4 and very few were stage 2
The CDR global scale based on cognitive, activities and social functioning is 0 (Normal); 0.5 (in different references: questionable dementia, very mild dementia or MCI); 1.0 (Mild dementia) ,2.0 (moderate),3.0 (severe).
The FDA in the 2024 guidance clearly links most MCI patients (CDR 0.5) to Stage 3 with this: "Stage 3: Patients with characteristic pathophysiological changes of AD, generally more apparent detectable abnormalities on sensitive neuropsychological measures, and mild but detectable functional impairment. The functional impairment in this stage is not severe enough to warrant a diagnosis of overt dementia. This stage roughly corresponds with the syndrome of “mild cognitive impairment”; however, it is noted that the term “mild cognitive impairment” may also encompass patients in late Stage 2 or early Stage 4." Some CDR 0.5 patients might be 2 and some might be 4 but majority will be Stage 3.
I know some people think I post FUD but they believe everything from Dr. Sabbagh. He links MCI to FDA Stage 3 in this article
https://pubmed.ncbi.nlm.nih.gov/34101796/
The 5 stages in this chart map to CDR 0, 0.5, 1.0, 2.0, 3.0
So knowledgeable neurologists consider MCI to mostly map to FDA Stage 3. Therefore most patients in the trial were FDA Stage 3 and 4 and very few were stage 2
