Cardiac interoceptive accuracy is not altered by acute stress

Interoception is the sense to process and perceive inner
bodily processes (e.g., organ activity). Stress affects and
possibly alters interoceptive signal processing. For example,
acute stress stimulates the cardiovascular system,
thereby increasing organ activity, which may ultimately
feed into enhanced cardiac perception, indicated by the
ability to count one's own heartbeats (i.e., interoceptive
accuracy/IAcc). Furthermore, cortisol release may also
affect the processing of cardiac signals at cortical level.
Hence, we hypothesized that an acute stressor enhances
cardiac IAcc, dependent on augmented sympathetic activation
(i.e., heart rate), and cortisol release. We investigated
cardiac IAcc in a heartbeat counting task (HCT)
before and after (0, 20, 40 min.) a stress test (SECPT vs.
control; n=33 each). IAcc and heart rate (HR) were neither
effected by stress, nor changed over time. In addition, the
number of counted heartbeats did not change, although
participants were significantly stressed (self-report
and
salivary cortisol). We also found a tendency of underreporting
heartbeats by 56% independent of group and time.
Furthermore, the given constant heart rate (M=81.5 bpm)was positively correlated with IAcc (M=.43) independent
of all conditions (r=.962, p<.001). IAcc in the HCT is determined
by changes in organ activity (i.e., HR), but not
by cortisol. As the SECPT did not change HR, the SECPT
and/or the HCT may have limited suitability for investigating
acute stress effects on cardiac interoception.