Does altitude moderate the impact of lithium on suicide? A spatial analysis of Austria

Abstract

Abstract. 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.

Hypobaric Hypoxia Induces Depression-like Behavior in Female Sprague-Dawley Rats, but not in Males

“…Regional variation in suicide rates in the United States correlate directly with state peak elevation (Haws et al, 2009) and county elevation , despite the decrease in overall mortality rates with altitude . The link between suicide and altitude of residence is also documented in Austria (Helbich et al, 2013) and South Korea . Depression is strongly associated with suicide in the developed world (Henriksson et al, 1993), and mortality by suicide is highly linked to unresolved depression ( Joiner et al, 2005).…”

Ketamine and suicidal ideation in depression: Jumping the gun?

“…In the recent past, epidemiological studies have attempted to correlate lithium in drinking water and suicide prevalence [138,139]. Studies have revealed a marginal but notable decrease in suicide rates with increased levels of lithium in drinking water in Japanese males [140], in Japanese females [141] and significant effects in populations in Greece [142], Austria [143][144][145], and Texas [146], but no such effect in the east of England [147]. Systematic reviews and meta-analysis reports upheld the effectiveness of lithium in averting suicide, particularly associated with mood disorders [148][149][150][151][152].…”

Data on Healthy Food Accessibility in Amsterdam, The Netherlands

“…While the original research paper [9] applied contextual neural gas [16,17] to account for spatial autocorrelation [18], we complement this spatially explicit approach with a non-spatial analysis using widely applied self-organizing maps (SOMs) [19,20] (other options can be found in [21]). A SOM is an unsupervised artificial neural network for data clustering and visualization [19].…”