Asymmetric increase in episodic and procedural memory interference in older adults

In younger adults, newly formed procedural memories are weakened by the subsequent formation of episodic memories (E→P interference) and vice versa (P→E interference; “cross-memory interference”). Older adults experience significant decline in episodic memory but maintain relatively intact procedural memory. This asymmetric decline in memory may also cause an asymmetric change in cross-memory interference compared to younger adults. For example, older adults may experience a significant increase in one type of cross-memory interference while leaving the other unchanged. Additionally, decline in episodic memory may cause E→P interference to either increase or decrease depending on how the episodic and procedural memory systems interact. However, no study to our knowledge has compared cross-memory interference between younger and older adults. We investigated cross-memory interference in younger and older adults by measuring E→P (Exp. 1) and P→E (Exp. 2) interference in 40 younger (18-40 years old) and 40 older (≥ 55 years old) adults. Compared to younger adults, the results show that older adults experience significantly stronger E→P interference while P→E interference was statistically indistinguishable between groups. These results confirm that older adults experience an asymmetric increase in cross-memory interference and suggest that the increase in E→P interference is related to the asymmetric decline in episodic memory relative to procedural memory.