The heartbeat evoked potential is a questionable biomarker in nightmare disorder: A replication study.

Frequent nightmares are common and linked to mental health problems, but their biological basis is poorly understood. A small 2019 study reported that the heartbeat evoked potential (HEP) measured during REM sleep differed markedly between 11 nightmare sufferers and 11 controls, and correlated with depression in the nightmare group, suggesting HEP could be a biomarker. This replication attempt analyzed HEPs in two larger databases (39 and 41 participants each) using the same methods. No significant HEP differences between groups were found in either database, nor any association with depression scores. These results cast doubt on HEP as a reliable biomarker for nightmare disorder and indicate that interpreting HEP as a marker of impaired arousal and emotional processing during REM sleep is premature.

Study at a glance

Abstract

Frequent nightmares are highly prevalent and constitute a risk factor for a wide range of psychopathological conditions. Despite its prevalence and clinical relevance however, the pathophysiological mechanisms of nightmares are poorly understood. A recent study (Perogamvros et, al 2019) examined the heart beat evoked potential (HEP) in a small group of nightmare sufferers (N = 11) and matched healthy controls (N = 11) and observed markedly different (Hedges' g = 1.42 [0.62-2.22]) HEP response across the groups during Rapid Eye Movement (REM) sleep. Moreover, the HEP correlated with depression scores in the nightmare group only. The authors concluded that the HEP in REM sleep could be used as a trait-like biomarker reflecting pathological emotional-and sleep regulation in nightmare disorder. To replicate the above study, we performed the same analyses of HEPs in two separate, and larger databases comprising the polysomnographic recordings of nightmare sufferers and matched controls (NStudy 1 = 39 ; NStudy 2 = 41). In contrast to the original findings, we did not observe significant differences in HEP across the two groups in either of the two databases. Moreover, we found no associations between depression scores and HEP amplitudes in the relevant spatiotemporal cluster. Our data cast doubts on the utility of HEP as a biomarker in the diagnostic and treatment procedures of nightmare disorder and suggests that the interpretation of HEP as a marker of impaired arousal and emotional processing during REM sleep is premature and requires further validation.