Psychosomatic symptoms during South East Asian haze crisis are related to changes in cerebral hemodynamics

Abstract

ObjectivesForest fires in South Asia lead to widespread haze, where many healthy individuals develop psychosomatic symptoms. We investigated the effects of haze exposure on cerebral hemodynamics and new symptoms. We hypothesised that vasoactive substances present in the haze, would lead to vasodilation of cerebral vasculature, thereby altering cerebral hemodynamics, which in turn may account for new psychosomatic symptoms.MethodsSeventy-four healthy volunteers were recruited, and serial transcranial Doppler (TCD) ultrasonography was performed to record blood flow parameters of bilateral middle cerebral arteries (MCA). The first TCD was performed in an air-conditioned environment. It was repeated outdoors after the participants spent 30-minutes in the haze environment. The prevailing level of pollutant standards index (PSI) was recorded. Appropriate statistical analyses were performed to compare cerebral hemodynamics at baseline and after haze exposure in all participants. Subgroup analyses were then employed to compare the findings between symptomatic and asymptomatic participants.ResultsStudy participants’ median age was 30 years (IQR 26–34), and new psychosomatic symptoms were reported by 35 (47.3%). There was a modest but significant decrease in pulsatility index (PI) and resistivity index (RI) in the left MCA after haze exposure (PI: p = 0.026; RI: p = 0.021). When compared to baseline parameters, haze exposure resulted in significantly lower mean PI (p = 0.001) and RI (p = 0.001) in symptomatic patients, but this difference was not present in asymptomatic patients (PI: p = 0.919; RI: p = 0.970).ConclusionHaze causes significant alterations in cerebral hemodynamics in susceptible individuals, probably responsible for various psychosomatic symptoms. The prognostic implications and health effects of haze require evaluation in a larger study.

Acute Health Impacts of the Southeast Asian Transboundary Haze Problem—A Review

“…In a prospective study on healthy subjects with transcranial Doppler investigations conducted prior and after haze exposure, it had been found that there was a modest but significant decrease in pulsatility index (PI) and resistivity index (RI) in the left middle cerebral artery after haze exposure. Haze exposure resulted in significantly lower mean PI and RI in symptomatic subjects compared to baseline parameters, but was not significantly different in the asymptomatic subjects [21].…”

“…The underlying pathophysiological mechanisms for haze exposure and neurological disease remain to be concretely elucidated. However, it has been postulated that some airborne particles in the transboundary haze may have vasoactive properties when inhaled, and may lead to alterations in cerebral hemodynamics [21]. It appeared that some subjects were more susceptible to these changes than others, and that alterations in the cerebral hemodynamics were correlated with the observed neurological symptoms, such as headaches.…”

“…The vast majority of studies investigating the acute health impact of seasonal haze in Southeast Asia has demonstrated an association between haze exposure and deleterious health effects, which range from physical and psychosomatic symptoms to respiratory, neurological, cardiovascular disease and mortality [18,20,21,23,24,25,26,27,28,29,30,31,32,33,34,35,41,42]. However, the evidence as a whole remains largely inconclusive for several reasons.…”

The Relationship Between Air Pollution and All-Cause Mortality in Singapore

“…In this study, we have demonstrated an association between exposure to elevated PSI levels and an increased short-term risk of mortality in Singapore. Air pollution is a tremendous public health issue, and our study has incorporated the Singapore context into the existing and growing body of evidence on the effect of air pollution on health [12,22,[52][53][54][55][56].…”

“…It is well established that both long-term [2] and short-term [3][4][5] exposure to ambient air pollution impact mortality, in particular cardiovascular and respiratory mortality. Although the deleterious effects of air pollution have been demonstrated in many Western countries [6][7][8], there are fewer comparable studies conducted in Asia [9][10][11][12][13][14]. Meanwhile, air quality remains a major problem in Asian cities, with effects on cardiovascular and respiratory mortality noted in time-series data [9,15,16], along with significant public health implications [17].…”