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Increased variability accompanies frontal lobe damage in dementia.
Susan Murtha1, Roxanna Cismaru, Randall Waechter
1Bloomfield Centre for Research in Aging, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada.
Summary
Frontal lobe dementia (FLD) patients exhibit significantly greater performance variability on cognitive tests compared to Alzheimer's type dementia and healthy controls. This increased variability is a key indicator of frontal lobe pathology.
Area of Science:
- Neuropsychology
- Neurology
- Cognitive Science
Background:
- Performance variability on neuropsychological tests is multifaceted, with different measures capturing distinct aspects of inconsistency.
- Increased performance variability has been hypothesized as a potential biomarker for frontal lobe pathology.
Purpose of the Study:
- To investigate whether increased performance variability is a specific characteristic of frontal lobe dementia (FLD).
- To differentiate patterns of variability across different cognitive measures and complexity levels in FLD.
Main Methods:
- Administered Stroop and Reaction Time tests weekly for 5 weeks to 3 groups: FLD, dementia of the Alzheimer type (DAT), and elderly normal controls (ENC).
- Assessed three types of variability: consistency (temporal fluctuations), diversity (between-participant), and dispersion (within-participant).
- Utilized subtests varying in complexity within each cognitive measure.
Main Results:
- The FLD group demonstrated significantly greater consistency and diversity variability on the Stroop task across all complexities.
- FLD also showed greater consistency and diversity variability on Reaction Time tasks, with patterns differing by subtest complexity.
- No significant increase in dispersion variability was observed in FLD patients.
Conclusions:
- The findings confirm the hypothesis that increased performance variability is associated with frontal lobe dementia.
- The study highlights the distinct nature of consistency, diversity, and dispersion measures of variability in dementia populations.