Department of Geosciences and Geography, University of Helsinki, Gustaf Hällströmin Katu 2a, 00014, Helsinki, Finland,
Environ Health Prev Med. 2013 Nov;18(6):494-501. doi: 10.1007/s12199-013-0348-4. Epub 2013 Jul 9.
Suicide mortality varies in both the short and long term. Our study examines suicide mortality in Finland and Sweden from the 1750s until today. The aim of our study is to detect any seasonal peaks in suicide rates and examine their temporal evolution to suggest a mechanism that may explain such peaks.
We acquired the study material from the Finnish and Swedish cause of death statistics (257,341 deaths by suicide) and the relevant population gender structure data. We then separately calculated the annual male and female suicide rates per 100,000 inhabitants. We analysed the suicide peaks, calculating factors of proportionality for the available data by dividing the suicide rates in the peak months (May and October) by the annual suicide rates.
Suicide rates in Finland and Sweden peak twice a year. Both men and women in both countries most often commit suicide in May. There is another peak in October, with the exception of Finnish men. These suicide peaks coincide with a temperature increase in May and the biggest annual drop in temperature in October. We also observed a monotonic long-term change in the Swedish statistics, but not in the Finnish data. Our hypothesis is that seasonal variation in suicide rates may be caused by abrupt temperature changes twice a year that trigger the activity in brown adipose tissue and deepen depression.
While the overall suicide mortality rates varied considerably, the monthly proportions in May did not. This finding suggests a routine factor underlying the spring peak in suicide mortality.
自杀死亡率在短期和长期内都存在差异。我们的研究考察了从 18 世纪 50 年代至今芬兰和瑞典的自杀死亡率。本研究的目的是检测自杀率是否存在季节性高峰，并研究其时间演变，以提出一种可能解释这种高峰的机制。
我们从芬兰和瑞典的死因统计数据（257341 例自杀）和相关的人口性别结构数据中获取了研究材料。然后，我们分别计算了每 10 万居民中男性和女性的年度自杀率。我们分析了自杀高峰，通过将高峰月份（5 月和 10 月）的自杀率除以年度自杀率，为可用数据计算比例因子。
芬兰和瑞典的自杀率每年出现两次高峰。两国的男性和女性通常在 5 月自杀。除了芬兰男性外，10 月还有另一个高峰。这些自杀高峰与 5 月的气温升高和 10 月的最大年度气温下降相对应。我们还观察到瑞典统计数据的长期单调变化，但芬兰数据没有。我们的假设是，自杀率的季节性变化可能是由每年两次的剧烈温度变化引起的，这种变化会引发棕色脂肪组织的活动，加深抑郁。
尽管总体自杀死亡率差异很大，但 5 月的月度比例没有变化。这一发现表明，自杀死亡率春季高峰存在一个潜在的规律因素。
