Associations Between Inactivity and Cognitive Function in Older Intensive Care Unit Survivors.

Area of Science:

• Gerontology
• Intensive Care Medicine
• Neuroscience

Background:

• Critically ill older adults exhibit profound inactivity in the intensive care unit (ICU), a pattern that often continues post-discharge.
• Older ICU survivors, particularly those who were mechanically ventilated, face a high risk of cognitive impairment after their ICU stay.

Purpose of the Study:

• To investigate the association between the ratio of daytime to nighttime physical activity and executive function in older adults who have survived the ICU.
• To determine if activity patterns can predict cognitive outcomes in this vulnerable population.

Main Methods:

• A secondary analysis utilized pooled data from two studies involving older, previously independent adults who were mechanically ventilated in the ICU.
• Actigraphy measured daytime and nighttime activity levels, from which a daytime-to-nighttime activity ratio was calculated.
• Executive function was assessed using the NIH Toolbox Dimensional Change Card Sort Test (DCCST), with multivariate regression analyzing the relationship between the activity ratio and DCCST scores, adjusting for age and grip strength.

Main Results:

• The average daytime-to-nighttime activity ratio was 2.10 ± 1.17.
• A notable proportion of participants (13.6%) exhibited higher activity during nighttime hours than during the day.
• A higher daytime-to-nighttime activity ratio was significantly associated with better performance on the DCCST (executive function).

Conclusions:

• The observed low proportion of daytime activity relative to nighttime activity indicates significant disruptions in the rest-activity cycle among older ICU survivors.
• Higher daytime-to-nighttime activity ratios correlate with improved executive function, suggesting this ratio is a potential early indicator of cognitive risk.
• Interventions promoting daytime physical activity and regular nighttime sleep may be crucial for accelerating recovery and enhancing cognitive function in older ICU survivors.