Neural Correlates of Mild Behavioral Impairment in older adults across the neurodegenerative spectrum
Bibliographic record
Abstract
Abstract Background Mild behavioral impairment (MBI) is a syndrome characterized by later life onset, persistent neuropsychiatric symptoms (NPS) in non‐demented older adults. MBI can co‐occur with Mild Cognitive Impairment (MCI) and has a range of neurodegenerative etiologies including Alzheimer’s disease (AD), Cerebrovascular Disease (CVD), and Parkinson’s disease (PD). MBI is associated with poorer cognitive and psychosocial function and an increased risk of developing dementia. Thus, we aimed to explore the structural neural correlates of MBI, specifically in the regions known to be associated with cognitive impairment (i.e., corticolimbic and frontal‐executive circuits), across multiple neurodegenerative diagnoses from the Ontario Neurodegenerative Disease Research Initiative (ONDRI). Method We assessed the association between MBI and brain structural alterations via T1‐weighted imaging in three groups with Montreal Cognitive Assessment scores ³19: individuals with MCI (due to AD; n = 37), CVD (n = 129), and PD (n = 127). NPS scores were derived from the Neuropsychiatric Inventory (NPI‐Q) domains, and categorized as NPS+ (i.e., NPI score>0); and NPS‐ (NPI score = 0). We selected regions of interest from the corticolimbic and frontal‐executive circuits to measure brain structure using cortical thickness and subcortical volume. Partial correlation, corrected for age, sex, and education was used to assess the association between MBI and brain structural alterations. Result Overall, apathy, depression, and anxiety, which map to the decreased motivation and emotional dysregulation MBI domains, had a high prevalence across all the groups. In the brain‐MBI association analysis, apathy was associated with decreased thickness of the l‐rostral middle frontal, r‐superior temporal, and frontal pole in the PD and CVD (but not MCI) groups. Anxiety was associated with decreased volume of the right hippocampus and amygdala in the MCI group, but not CVD or PD (FDR p< 0.05). No structural correlates were found for depression. Conclusion Our findings provide evidence of a specific association between apathy and reduced efficiency of the frontal‐executive system in individuals with PD and CVD. In addition, the well‐established AD corticolimbic atrophy patterns (e.g., hippocampus and amygdala) seen in MCI are prominent in the presence of anxiety. Overall, the relatively distinct brain‐MBI associations across neurodegenerative disorders suggest that pathological substrates may alter MBI neural correlates.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".