Neurocognitive Constructs Underlying Executive Control in Statistically-Determined Mild Cognitive Impairment

Area of Science:

• Cognitive Neuroscience
• Neuropsychology
• Clinical Neurology

Background:

• Executive attention theory posits temporal organization is crucial for executive control, influencing working memory, preparatory set, and inhibitory control.
• Mild cognitive impairment (MCI) is a transitional stage between normal aging and dementia, characterized by cognitive deficits.
• Understanding the temporal dynamics of executive functions is vital for early detection of cognitive decline.

Purpose of the Study:

• To operationally define executive attention constructs using intra-component latencies from a backward digit span test.
• To investigate temporal organization differences in patients with and without MCI.
• To explore the utility of reaction time metrics as neurocognitive biomarkers for MCI.

Main Methods:

• An iPad version of the Backward Digit Span Test (BDT) was administered to 58 memory clinic patients (22 with MCI, 36 without).
• Intra-component latencies for correct 5-span serial order responses were measured as outcome variables.
• Patients were classified into MCI and non-MCI groups based on diagnostic criteria.

Main Results:

• No significant difference in average total test time was observed between groups.
• A significant interaction revealed distinct temporal epochs in serial order response latencies.
• Non-MCI patients showed slower responses in early (working memory/preparatory set) and late (inhibitory control) stages, while MCI patients exhibited slower middle-stage (preparatory set) responses.

Conclusions:

• Analysis of 5-span BDT serial order latencies identified distinct time allocation epochs during successful task performance.
• Intra-component latencies from mental re-ordering tasks may serve as valuable neurocognitive biomarkers for early neurodegenerative conditions.
• Specific temporal patterns in executive function tasks can differentiate individuals with and without MCI, suggesting potential for early diagnostic markers.