id_827. ULTRA SHORT HRV AS AN AUTONOMIC MARKER FOR NEUROCOGNITIVE EXPERIMENTS: VALIDATION ACROSS RESTING STATE CONDITIONS IN A PLACEBO CONTROLLED CAFFEINE STUDY
Cezary Zając1, Karina Maciejewska2, Klaudia Duch2, Maciej Giza3, Aleksandra Nas3
1 University of Silesia in Katowice, College of Interdisciplinary Individual Studies, ul. Bankowa 12, 40-007 Katowice, Poland
2 University of Silesia in Katowice, Faculty of Science and Technology, Institute of Biomedical Engineering, ul. 75 Pulku Piechoty 1a, 41-500 Chorzow, Poland
3 Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, Radiotherapy Planning Department, Wybrzeze Armii Krajowej 15, 44-102 Gliwice, Poland
INTRODUCTION: Heart rate variability (HRV) is a widely used index of autonomic nervous system activity that complements central measures in cognitive neuroscience by tracking arousal, parasympathetic regulation, and sympathovagal balance. Current clinical guidelines recommend at least 5 min of ECG for short term HRV analysis, limiting use in trial based designs and dynamic paradigms where psychophysiological state changes rapidly.
AIM(S): We aimed to validate ultra short HRV (ustHRV) measures against the 5 min benchmark across multiple recording lengths and psychophysiological conditions.
METHOD(S): We analyzed ECG from 47 participants in a double blind placebo controlled study assessing an energy supplement containing caffeine versus matched control. Recordings were acquired during eyes-open and eyes-closed resting states at three time points: before supplementation, 30 min, and 90 min after. Three time domain (RMSSD, SDSD, pNN50) and five frequency domain indices (HF power, LF power, normalized HF, normalized LF, LF to HF ratio) were computed from 10 s, 30 s, 1 min, 2 min, 3 min, and 4 min segments and compared with 5 min reference values.
RESULTS: Across correlation analyses, intra and inter group tests, trend analyses, and Bland Altman agreement, time domain indices and HF power from 30 s segments showed good concordance with 5 min benchmarks, whereas other frequency measures generally required 1 to 2 min segments. Our findings align with HRV electrophysiology: slower frequency measures are more sensitive to state changes such as mental fatigue. Eyes open versus closed conditions did not substantially alter optimal segment length when recordings were brief, but extended sessions inducing sleepiness or fatigue may require longer ECG to preserve agreement.
CONCLUSIONS: These results support ustHRV as a feasible autonomic marker for neurocognitive studies with constrained time windows, while highlighting that optimal segment length should match expected state stability during tasks rather than being a fixed rule.
FINANCIAL SUPPORT: The research activities were co-financed by the funds granted under the Research Excellence Initiative of the University of Silesia in Katowice.