Core features of depersonalization/derealization disorder (DPD) are emotional numbing and feelings of disembodiment. Although there are several neurophysiological findings supporting subjective emotional numbing, the psychobiology of disembodiment remains unclear.
Heartbeat-evoked potentials (HEPs), which are considered psychophysiological indicators for the cortical representation of afferent signals originating from the cardiovascular system, were assessed in 23 patients with DPD and 24 healthy control individuals during rest and while performing a heartbeat perception task.
Absolute HEP amplitudes did not differ between groups. Nevertheless, healthy individuals showed higher HEPs during the heartbeat perception task than during rest, whereas no such effect was found in patients with DPD (p = .031). Patients with DPD had higher total levels of salivary α-amylase than did healthy individuals (9626.6 [8200.0] versus 5344.3 [3745.8] kU min/l; p = .029), but there were no group differences in cardiovascular measures (heart rate = 76.2 [10.1] versus 74.3 [7.5] beats/min, p = .60; normalized low-frequency heart rate variability = 0.63 [0.15] versus 0.56 [0.15] normalized units, p = .099; low frequency/high frequency ratio = 249.3 [242.7] versus 164.8 [108.8], p = .10), salivary cortisol (57.5 [46.7] versus 55.1 [43.6] nmol min/l, p = .86), or cortisone levels (593.2 [260.3] versus 543.8 [257.1] nmol min/l, p = .52).
These results suggest altered cortical representation of afferent signals originating from the cardiovascular system in patients with DPD, which may be associated with higher sympathetic tone. These findings may reflect difficulties of patients with DPD to attend to their actual bodily experiences.