Association of solar variability and space weather factors with parameters of clinical chemistry, hematology, hemostasis, in- flammatory biomarkers and heart rate variability in a middle- aged to elderly population-based cohort

Heliobiological studies investigated the effects of solar variability on human health through epidemiological approaches. Hospital statistics revealed associations between geomagnetic disturbances and blood flow-related pathologies like myocardial infarction or stroke. Further clinical studies, looking at parameters like heart rate variability (HRV), discovered underlying physiological processes, yet they could not explain the biophysical mechanisms. In order to broaden physiological understanding, this study explored changes in the hematovascular system due to dynamics in solar- and geomagnetic activity. A dataset of 40 blood parameters alongside HRV measures for 1,779 non-hospitalized individuals between 45 and 83 years of age was compared to solar-, cosmic-ray-, and geomagnetic activity indicators during the solar minimum period between years 2007 - 2010. Demographic subgroups regarding age, gender, health scores and certain pathologies were analyzed. Correlations from clinical- and geospace-data were assessed for different time-lags between both datasets, applying signal smoothing methods and Bonferroni correction. Increased levels for certain differential leucocytes, inflammatory markers, and glycated hemoglobin A1c were observed for long-term periods of increased cosmic-ray intensity paired with reduced geomagnetic activity (p<0.01) – which accounts to an increase in cardiovascular disease (CVD) risk factors comparable with other studies during similar periods. Similar correlations were noted in liver and kidney function markers. No significant correlations were found for red blood cell parameters and routine clinical coagulation factors. For lipid parameters, an increase in the Apolipoprotein B / A1 ratio was found for long-term periods of higher solar radio flux F10.7 (p<0.01) – resulting in another increased CVD risk factor. On shorter timescales, peaks in Total- and LDL-Cholesterol were observed following space-weather events after a delay of 6 days (p<0.01) – a characteristic time-lag behavior corresponding with similar heliobiological studies. HRV parameters showed an increase in absolute power across all frequency bands and in SSDN for periods of increased geomagnetic activity with a time-lag of 3 - 4 days. Regarding the interplay of HRV with inflammation factors, connections to the blood parameter findings of present study were established. Demographic subgroup analysis revealed significant dependances on individual factors: Inflammatory responses were most pronounced in male subjects within the youngest age group (49 – 62 y.). Further, results were more expressed in subjects with a lower KSK-12-health score and suffering from hypertension or stroke / myocardial infarction in the past. This study established a foundation for heliobiological research on clinical chemistry. It has shown highly significant correlations analyzing blood parameters in a large cohort of elderly participants in the northern hemisphere, which depended significantly on demographic factors and – as demonstrated by the analysis of solar cycle subwindows - on the solar cycle macrophase, as well.