The Effects of Aging and Time of Day on Inhibitory Control: An Event-Related Potential Study

Area of Science:

• Cognitive Neuroscience
• Chronobiology
• Gerontology

Background:

• Circadian rhythms and time of day (TOD) significantly influence executive functions, with optimal performance occurring at an individual's preferred TOD (synchrony effect).
• Older adults (OAs) experience natural declines in inhibitory control and are more susceptible to circadian variations affecting cognitive performance.
• Previous research has not explored the combined impact of aging and TOD on executive functioning using electrophysiological methods.

Purpose of the Study:

• To investigate the effects of aging and TOD on the neural correlates of inhibitory processing using event-related potentials (ERPs).
• To examine the synchrony effect on inhibitory control in younger adults (YAs) and OAs under optimal and non-optimal testing conditions.

Main Methods:

• Two groups, 52 OAs (morning chronotype) and 51 YAs (afternoon/evening chronotype), participated.
• Participants were randomly assigned to either morning or afternoon testing sessions, aligning with their optimal or non-optimal TOD.
• The Go-NoGo and Flanker tasks were used to assess inhibitory control, with N2 and P3 components of ERPs analyzed.

Main Results:

• Behavioral data showed no significant TOD effects on performance for either age group.
• Electrophysiological data revealed synchrony effects: both YAs and OAs exhibited greater N2 modulation (Go-NoGo) and P3 amplitude (Flanker) during non-optimal TOD.
• Age-related differences in P3 amplitude for the Flanker task were only observed during non-optimal testing times, indicating reduced interference control efficiency in OAs.

Conclusions:

• TOD and aging differentially affect inhibitory control processes, particularly interference control, with older adults showing reduced efficiency during off-peak testing hours.
• ERPs are sensitive to TOD effects on cognitive control, even when behavioral measures do not show significant differences.
• Findings underscore the importance of considering and controlling for individual chronotypes in research involving cognitive function across the lifespan.