Neurocognitive aging
Does cognitive frailty in old age signal early Alzheimer's?
Open access · cc by · source: Europe PMC
Older adults with cognitive frailty show brain structures and electrical responses similar to healthy peers, rather than those with Alzheimer's disease.
How this study connects
Role on claims
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Simultaneous EEG/MEG recordings of mismatch responses during cross-modal tasks can distinguish cognitively frail older adults, who show preserved mismatch responses, from Alzheimer's disease patients who show diminished responses.
Evidence for the claim as stated.
Study at a glance
- Design
- Case-control — Structural MRI plus simultaneous EEG/MEG mismatch responses in cognitive frailty vs healthy older, MCI, and AD
- N
- Community-dwelling cognitively frail older adults, healthy controls (MMSE >25 or ACE-R >88), and clinic MCI/AD; exact cell sizes not extracted as a single N
- Population
- Older adults who are cognitively frail, healthy, or diagnosed with MCI or Alzheimer's disease
- Outcome
- Hippocampal volume and mismatch responses distinguishing cognitive frailty from Alzheimer's-type neurodegeneration
Structured fields used in claim comparison tables when every cited study has a complete layer.
Inspect source passages
Does cognitive frailty in old age signal early Alzheimer's?
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
The score threshold of 25 on the Mini Mental State Examination used to define healthy cognitive controls
These healthy cognitive controls scored >25/30 on MMSE or >88/100 on the ACE-R during the home interview.
The total number of standard trials presented to each participant
There were in total 1000 STD trials; and DA, DN, and target trials were presented 48 times each.
Key findings
The researchers discovered that cognitively frail older adults do not show the brain atrophy or neurophysiological deficits characteristic of early Alzheimer's disease. Structurally, the cognitively frail group had hippocampal and entorhinal cortex volumes that were similar to healthy controls and significantly larger than those of patients with mild cognitive impairment or Alzheimer's. Additionally, during the learning task, their brain mismatch responses to novel and associative changes were preserved and matched the healthy controls, unlike the diminished responses observed in the patient groups. Instead of latent neurodegenerative disease, their poor cognitive scores were linked to lifestyle and socioeconomic factors, such as lower educational levels, hearing impairments, and cardiovascular risks.
Methodology
Researchers compared community-dwelling older adults who were cognitively frail with healthy controls and patients diagnosed with mild cognitive impairment or Alzheimer's disease. To screen for cognitive frailty, the researchers identified individuals scoring below 25 out of 30 on the Mini Mental State Examination or below 88 out of 100 on the Addenbrooke's Cognitive Examination–Revised. Participants underwent brain structural MRI and simultaneous EEG/MEG recordings during a cross-modal learning task consisting of 1000 standard trials and 48 trials each of sensory and associative deviations.
Limitations
Because the study used a cross-sectional design, it cannot prove whether cognitively frail individuals will eventually progress to dementia or track their long-term cognitive trajectory. The researchers also did not measure direct biological markers of Alzheimer's disease, such as amyloid-beta or tau proteins from spinal fluid or PET scans, which limits their ability to completely rule out early-stage pathology. Additionally, the cognitive screening thresholds used might have misclassified some individuals because typical cognitive tests are heavily influenced by a participant's educational background rather than purely reflecting brain health.
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