Intraindividual variability measured with dispersion across diagnostic groups in a memory clinic sample

Area of Science:

• Neuroscience
• Cognitive Psychology
• Geriatrics

Background:

• Increased intraindividual variability (IIV) is associated with cognitive decline and dementia.
• IIV may offer diagnostic insights beyond traditional neuropsychological assessments.
• Dispersion, a subtype of IIV, warrants investigation for its diagnostic utility in dementia.

Purpose of the Study:

• To determine if cognitive dispersion provides additional diagnostic information for dementia.
• To compare dispersion patterns across different cognitive status groups: subjective cognitive impairment (SCI), amnestic mild cognitive impairment (a-MCI), and Alzheimer's disease (AD).

Main Methods:

• Calculated dispersion as intraindividual standard deviations across neuropsychological measures in executive functioning, immediate memory, and delayed memory.
• Analyzed dispersion using profile analysis in memory clinic patients stratified into SCI (n=85), a-MCI (n=16), and AD (n=48) groups.

Main Results:

• Patients with AD and a-MCI exhibited significantly less dispersion in delayed memory compared to patients with SCI.
• Findings align with theories on cognitive variability and age-related decline.
• Potential floor effects may suppress dispersion in amnestic presentations, particularly in delayed memory.

Conclusions:

• Cognitive dispersion shows potential as a diagnostic marker, especially differentiating SCI from amnestic impairments.
• Further research is needed to explore IIV in SCI versus control groups and its role in immediate memory and executive functioning.
• The clinical significance of IIV in distinguishing between impairment and no impairment requires further investigation.