天氣可能是自殺行為的生物環境危險因子之一,此課題早為學界所關注,然而由於研究方法的不同,天氣對於自殺的影響目前仍無一致的結論。本文回顧過去探討該主題的相關文獻,指出欲探討天氣與自殺的關係,必須先考慮相關研究在研究方法、研究對象、研究地區等方面的異同,而天氣變項資料的選擇與干擾因子的控制,會使得研究結果的臨床意涵與外在效度有所不同。在天氣變項的選擇上,以每週、每月或每年天氣變化為暴露因子的研究均為生態研究,可能因無法控制的干擾因子而影響結果。而以每天的天氣變化為暴露因子的研究,考慮的是逐日的天氣改變是否造成易感受者額外的壓力而導致自殺。天氣變化可能導致自殺發生的理論假說涵蓋神經生物學觀點,以及社會學與人際關係觀點,天氣變化可能影響腦內血清素的活性,也可能增加人際衝突的機會,它們有可能導致自殺行為的發生。進一步的研究應考慮自殺行為的異質性、樣本數是否充足,並納入生物精神醫學之証據以增加研究之效度。
Weather has been considered as a potential bio-environmental risk factor for suicide for long time. However, given different study approaches, the relationship between weather and suicide is far from reaching consensus yet. This paper has reviewed relevant literatures; differences in research methodology are discussed in terms of study population, study region, selection of weather parameters and controlling of confounding factors. Differences in study design may have influenced internal and external validity of studies. Ecological studies using weekly or monthly weather parameters as risk exposure were prone to ecological fallacy due to uncontrollable confounding factors. Studies using daily weather parameters have hypothesized weather change to be an acute additional stress to the vulnerable individuals. Hypothesis concerning underlying mechanism included neurobiological theory and sociological theory. Effects of weather on brain serotonin function and interpersonal conflict may be involved in the occurrence of suicidal behavior. Further studies might consider suicidal behavior as heterogeneous, employing adequate sample size, and incorporating evidence in biological basis to achieve better validity and understanding in this field.