Abstract
This investigation was inspired by growing evidence that middle-aged persons in a cognitively demanding profession might be characterized by subtle cognitive fatigue. We studied young and middle-aged male schoolteachers. They were compared in a study with functional magnetic resonance imaging to evaluate differences during successful memory encoding. The schoolteachers were additionally subjected to an induced fatigue condition involving the sustained performance of cognitively demanding tasks and to a control condition. Results showed age-related brain activation differences underlying behavioral performance including: (1) greater activation in middle-aged vs. young teachers in bilateral prefrontal cortex (PFC) areas; and (2) differential fatigue effects in the left anterior cingulate cortex (ACC) depending on age group. Middle-aged schoolteachers showed decreased ACC activation in the fatigue compared to the control condition, whereas no change in activation was found in young teachers. Findings demonstrate age effects in these middle-aged subjects that are typically found in older adults, specifically in PFC over-activation. Findings also indicate that already in middle age cognitive aging may be associated with greater resource depletion following sustained task performance. The findings underscore the notion that persons in a cognitively demanding profession can experience subtle age effects, which are evident on fMRI and which impact daily functioning. Possible practical implications for middle-aged schoolteachers are discussed.
Highlights
Given findings from previous studies, we focused on age and fatigue condition effects in the prefrontal cortex (PFC) and medial temporal lobe (MTL), based on Anatomical Automatic Labeling (AAL) regions defined according to the SPM8 WFU pickatlas (Tzourio-Mazoyer et al, 2002; Maldjian et al, 2003, 2004), using the small volume correction option in SPM8 to construct 12 mm radius spheres centered around the peak voxels identified for the main effect of task, which is orthogonal with respect to group and condition interaction effects (Kriegeskorte et al, 2009)
In the present study we examined the effects of age and induced cognitive fatigue on brain activation associated with the subsequent memory operationalization of successful encoding in young and middle-aged schoolteachers
Greater activation was found in middle-aged than young teachers in left and medial PFC areas
Summary
Memory function declines across the adult lifespan (e.g., Park et al, 2002; Myerson et al, 2003; Salthouse, 2003; Bopp and Verhaeghen, 2005; van der Elst et al, 2005; Soei and Daum, 2008; van der Elst and Jolles, 2012), with episodic memory thought to show the greatest decline (Reuter-Lorenz and Park, 2010; but see Rönnlund et al, 2005). A recent fMRI experiment focused on negative subsequent memory and task-negative effects (de Chastelaine et al, 2011) These authors showed that suppression of activation within the default mode network is attenuated in middle-aged compared to young individuals during an encoding task. This suggests that middleaged individuals become less competent at reallocating internally directed processes to those necessary for accomplishing the task. Other recent studies (e.g., Park et al, 2013; Klaassen et al, 2014; Cansino et al, 2015) are consistent with the notion that there are subtle effects on memory-related functions in middle age, which are accompanied by fMRI changes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
