Examining the Stability and Predictive Utility of Across- and Within-Domain Intra-Individual Variability in Mild...

Area of Science:

• Neuropsychology
• Cognitive Neuroscience
• Neurology

Background:

• Intra-individual variability in neuropsychological tests, known as dispersion, can predict cognitive decline.
• Limited research exists on the stability and predictive value of both across- and within-domain dispersion.

Purpose of the Study:

• To investigate the stability and predictive utility of across- and within-domain dispersion in a longitudinal sample of individuals with mild cognitive impairment (MCI).
• To examine dispersion indices in predicting cognitive decline within the MCI population.

Main Methods:

• Longitudinal study of 238 MCI patients assessed at baseline and after 1.5 years.
• Linear regression analyzed baseline dispersion predicting cognitive decline (dichotomous and continuous measures).
• Cognitive decline operationalized by diagnostic conversion to dementia and standardized regression-based (SRB) z-scores.

Main Results:

• Dispersion measures were generally stable and correlated over time.
• No dispersion variables predicted conversion to dementia.
• Greater across-domain dispersion predicted greater overall cognitive decline (SRB z-scores), unlike most within-domain measures.

Conclusions:

• Across- and within-domain dispersion are relatively stable in MCI patients.
• Across-domain dispersion predicts subtle cognitive decline, but not dementia conversion.
• The choice of neuropsychological tests influences dispersion findings.