Aging increases episodic memory interference on skill consolidation despite episodic memory decline

Episodic memories are verbalizable and autobiographical, whereas procedural memories are expressed as skills and habits. Brown and Robertson (2007, J Neurosci) showed that episodic memory acquisition disrupts the wakeful consolidation of procedural memories in younger adults. Older adults experience age-related episodic memory decline, but relatively spared procedural memory, suggesting that episodic memory interference on procedural skill consolidation may be weaker in older adults. Alternatively, disrupted episodic memory processes may increase the effort or resources needed to encode those memories in older adults, causing greater interference in procedural memory consolidation. To adjudicate these possibilities, we recruited forty cognitively unimpaired younger (n = 20; 18-40 years old) and older (n = 20; ≥ 55 years old) adults to investigate how episodic memory interference on procedural memory consolidation compares between age groups. Skill performance was recorded using the serial reaction time task (SRTT) in the morning and 6-12 hours later. Immediately after the morning SRTT session, half of the participants in each age group acquired episodic memories, while the other half performed a control task. Contrary to Brown and Robertson (2007, J Neurosci), we found weak evidence of memory interference in younger adults. However, memory interference was evident in older adults and stronger than in younger adults. Thus, although episodic memory is weaker in older adults, our results show that episodic memory interference is stronger in older adults. These findings suggest that episodic memory does not just decline with age but can problematically influence procedural memory, possibly through compensatory processes.