Evaluation of the severity of dementia using expectation control function

Area of Science:

• Autonomic Nervous System Physiology
• Neuroscience
• Gerontology

Background:

• Animal studies suggest sympathetic nerve tone increases pre-behavior, indicating expectation control.
• This phenomenon's presence and implications in human daily life, particularly in dementia, remain under-investigated.

Purpose of the Study:

• To investigate the presence of expectation control in humans during daily activities.
• To determine if dementia patients exhibit altered expectation control compared to healthy adults.
• To explore the potential of using this function to objectively assess dementia severity.

Main Methods:

• Utilized Holter electrocardiography (ECG) with an acceleration sensor to record ECG and behavioral states.
• Analyzed RR interval frequency components (High Frequency - HF, Low Frequency - LF) to assess autonomic nerve tone (parasympathetic/sympathetic).
• Compared autonomic parameters during sustained rest versus immediately preceding intentional behaviors in 32 dementia patients and controls.

Main Results:

• Sympathetic nerve tone, indicated by decreased RR interval and HF component and increased LF/HF ratio, increased at rest before intentional behaviors in humans.
• Dementia patients showed significant alterations in these autonomic parameters compared to controls.
• The degree of sympathetic activation correlated with dementia severity.

Conclusions:

• The expectation control function, involving pre-behavioral sympathetic activation, is present in humans.
• This mechanism is impaired in dementia patients, with alterations related to disease severity.
• Autonomic responses during expectation may serve as an objective biomarker for dementia severity evaluation.