Breathing slower is not always better: Slow-paced breathing enhances heart rate variability but produces age-differential effects on emotional reactivity and memory

Slow-paced breathing (SPB) is commonly used to promote autonomic regulation and emotion regulation, but its effects on emotional memory, and whether these extend to older adults, have received little attention. We examined whether SPB during memory encoding would modulate heart rate variability (HRV), emotional reactivity, and recognition memory differently from normal-paced breathing (NPB) in younger (n = 82) and older (n = 84) adults. Participants breathed at either 6 breaths/min (SPB) or 12 breaths/min (NPB) while encoding negative and neutral images, then completed a recognition test with Remember/Know judgments. Both breathing conditions produced robust increases in task-related HRV, with no reliable difference between SPB and NPB; effects were comparable across age groups. SPB reduced overall emotional intensity and tended to dampen perceived negativity, though not in a valence-specific manner. At the memory level, older adults showed lower discrimination than younger adults, particularly for negative images, consistent with accounts of an age-related positivity effect characterized by a reduced advantage of negative over neutral material. SPB reduced false alarms and improved discrimination in younger adults, whereas older adults showed comparable performance across conditions. SPB reduced spurious recollection (Remember responses to lures) while preserving recollection of targets, and this effect did not differ by age group. Exploratory mediation analyses showed that task-related RMSSD did not significantly mediate the effects of breathing condition on any outcome, leaving unresolved whether the observed psychological effects depended on central, peripheral, or distributed mechanisms. Thus, slower breathing is not uniformly better: both paced-breathing conditions enhanced task-related HRV, whereas SPB reduced emotional intensity regardless of age and improved memory only in younger adults.