Helbich Marco, Blüml Victor, Leitner Michael, Kapusta Nestor D
Institute of Geography, University of Heidelberg, Berliner Strasse 48, Heidelberg, Germany.
Geospat Health. 2013 May;7(2):209-18. doi: 10.4081/gh.2013.81.
Suicide, the tenth leading cause of death worldwide, is a complex phenomenon. Models aiming to explain the interaction of ambient variables such as socioeconomic factors, lithium content of drinking water and altitude are poorly developed. While controlling for several risk factors, this research bridges two different, but complementary research lines by investigating statistically the relationship on suicide mortality between lithium levels in drinking water in response to altitude above sea level. Besides regression models with main effects, a multiplicative interaction model between lithium and altitude has been developed providing estimates at the district-level for Austria where spatial autocorrelation was accounted for through spatial filtering. The correlation results showed a negative association between lithium levels and altitude. The regression confirmed a negative association of lithium levels and suicide mortality. Altitude was found to be positively associated with suicide mortality. On the other hand, lithium effects on suicide mortality were found to be moderated by altitude. In lower altitude regions the effect turned out to be negatively related to suicide mortality, while lithium had a positive association in high-altitude regions. These results provide evidence for the fact that the relationship between lithium, altitude and suicide rates is more complex than hitherto assumed. Further research on the effects of ambient variables such as low levels of lithium on suicide is needed and particularly the lithium-altitude interaction is worth further investigation to understand possible underlying neurochemical processes.
自杀是全球第十大死因，是一种复杂的现象。旨在解释社会经济因素、饮用水锂含量和海拔等环境变量之间相互作用的模型尚不完善。在控制了几个风险因素的同时，本研究通过统计调查饮用水中锂含量与海平面以上海拔高度对自杀死亡率的关系，架起了两条不同但互补的研究线路之间的桥梁。除了具有主效应的回归模型外，还开发了锂与海拔之间的乘法交互模型，为奥地利提供了地区层面的估计值，其中通过空间滤波考虑了空间自相关。相关结果表明锂含量与海拔呈负相关。回归证实了锂含量与自杀死亡率呈负相关。发现海拔与自杀死亡率呈正相关。另一方面，发现锂对自杀死亡率的影响受海拔调节。在低海拔地区，这种影响与自杀死亡率呈负相关，而在高海拔地区，锂与自杀死亡率呈正相关。这些结果证明了锂、海拔和自杀率之间的关系比迄今所假设的更为复杂这一事实。需要进一步研究低水平锂等环境变量对自杀的影响，特别是锂-海拔相互作用值得进一步研究，以了解可能潜在的神经化学过程。
