Age-related differences in brain activity despite matched cognitive performance: A moderated-mediation analysis.

Younger and older adults did not significantly differ in their titrated cognitive capacity scores despite being different age groups.

• The sample consisted of 40 younger and 39 older healthy adults.
• Cognitive demands were titrated during a verbal delayed match to sample task within fMRI.
• The two age groups did not significantly differ in their titrated cognitive capacity scores, meaning both groups found the task equally challenging.
• Titration was used specifically to control for the confounding of task demands and perceived difficulty.

Despite matched cognitive performance, fMRI moderated-mediation analysis identified brain activity that differed significantly between younger and older adults.

• Between-group comparisons identified brain regions significantly related to behavioral performance.
• Brain regions were identified using the 'Reserve and Resilience Framework.'
• The relationships between brain activity and cognitive capacity differed between the two age groups.
• These differences were detected even though all participants performed a task they found equally challenging.

Results supported upregulation, reorganization, and suppression of brain activity as mechanisms related to both increases and decreases in cognitive capacity.

• Upregulation refers to increased recruitment of neural resources with age.
• Reorganization refers to age-related divergence in the recruitment of neural resources.
• Suppression of brain activity was identified as a mechanism related to cognitive capacity.
• Brain activity increases and decreases appeared to be balanced against each other to maintain high cognitive capacity.

A beneficial effect of suppressed brain activity on cognitive capacity was identified in the context of aging.

• Neural suppression was found to be associated with maintenance of high cognitive capacity.
• This finding supports the expansion of the current cognitive reserve and resilience framework.
• The current framework did not previously include neural suppression as a potential mechanism of healthy cognitive aging.
• Both increases and decreases in brain activity were implicated in supporting cognitive performance.

The study used a verbal delayed match to sample task with titrated cognitive demands administered during fMRI to control for perceived difficulty.

• Cognitive demands were titrated to equate perceived difficulty across individuals.
• The paradigm was designed to disentangle task demands from individual differences in difficulty.
• Between-group comparisons involved 40 younger and 39 older healthy adults.
• Moderated-mediation analysis was the primary statistical approach used to examine relationships between brain activity, age group, and cognitive capacity.

The authors argue that the cognitive reserve and resilience framework needs to be expanded to include neural suppression as a mechanism of healthy cognitive aging.

• Current findings showed a beneficial effect of suppressed brain activity.
• Prior frameworks supporting upregulation and reorganization did not fully account for suppression.
• The results suggest that maintenance of cognitive capacity in aging involves a balance between increases and decreases in brain activity.
• Neural suppression is proposed as an additional mechanism alongside upregulation and reorganization.