Aging increases the energetic demands of episodic memory: a cardiovascular analysis

We hypothesized that older volunteers allocate more attentional resources to memory maintenance than do younger volunteers. Allocation of a resource supporting memory maintenance was inferred from performance and cardiovascular measures. Eighteen 18- to 26-year-old men and eighteen 60- to 79-year-old men performed a serial memory task both as a single task and as a dual task that added simple reaction time stimuli. Items presented early or later in the serial list created relatively low or high memory load. The results suggested that older men allocated greater attention to memory maintenance, particularly during high-memory-load items. They showed a slowing of dual-task reaction time and increased heart rate during high- vs. low-memory-load items. Cardiac and vascular reactions further suggested that memory maintenance is supported by phasic autonomic adjustments and that with age, more of this support is required for adequate maintenance of episodic memory.