Olfactory context and memory across the adult lifespan: effects on mnemonic discrimination and olfactory function.

Abstract

Odor is a powerful contextual cue that can influence memory and is closely linked to brain regions involved in episodic memory, including the hippocampus. Age-related olfactory dysfunction is among the earliest behavioral changes associated with cognitive decline and may contribute to memory impairments in older adults. Hippocampal pattern separation, or the process of reducing interference among similar experiences, provides a sensitive measure of age-related memory decline, yet little is known about how olfactory context influences mnemonic discrimination. In the present study, we examined whether odor context during encoding affects subsequent mnemonic discrimination in young and older adults. Participants completed a mnemonic similarity task in which object stimuli were encoded in both odor (lavender) and no-odor contexts prior to a memory test. Across participants, odor context did not significantly influence target recognition or mnemonic discrimination. Consistent with prior work, older adults exhibited poorer mnemonic discrimination and reduced olfactory function relative to young adults. However, odor presentation order influenced mnemonic discrimination in older adults, such that performance was better when the odor context was encountered during the first encoding block compared to the second. Additionally, poorer olfactory function was associated with reduced mnemonic discrimination, and this relationship was largely explained by age-related differences in olfactory ability. These findings suggest that the influence of olfactory context on memory depends on both age and the timing of odor exposure, highlighting the importance of individual differences in olfactory function when evaluating odor-based approaches to support memory in aging.