Department of Psychiatry, Harvard Medical School, McLean Imaging Center, McLean Hospital, 115 Mill St, Belmont, MA, 02478, USA.
Department of Biostatistics and Department of Psychiatry, Harvard Medical School, Laboratory for Psychiatric Biostatistics, McLean Hospital, 115 Mill St, Belmont, MA, 02478, USA.
BMC Psychiatry. 2021 Mar 16;21(1):153. doi: 10.1186/s12888-021-03159-5.
Nearly 800,000 suicides occur worldwide annually and suicide rates are increasing faster than population growth. Unfortunately, the pathophysiology of suicide remains poorly understood, which has hindered suicide prevention efforts. However, mechanistic clues may be found by studying effects of seasonality on suicide and other mortality causes. Suicides tend to peak in spring-summer periods and nadir in fall-winter periods while circulatory system disease-related mortality tends to exhibit the opposite temporal trends. This study aimed to determine for the first time whether monthly temporal cross-correlations exist between suicide and circulatory system disease-related mortality at the population level. If so and if common biological factors moderate risks for both mortality types, such factors may be discoverable and utilized to improve suicide prevention.
We conducted time series analyses of monthly mortality data from northern (England and Wales, South Korea, United States) and southern (Australia, Brazil) hemisphere countries during the period 2009-2018 (N = 41.8 million all-cause mortality cases). We used a Poisson regression variant of the standard cosinor model to determine peak months of mortality. We also estimated cross-correlations between monthly mortality counts from suicide and from circulatory system diseases.
Suicide and circulatory disease-related mortality temporal patterns were negatively correlated in Australia (- 0.32), Brazil (- 0.57), South Korea (- 0.32), and in the United States (- 0.66), but no temporal correlation was discernable in England and Wales.
The negative temporal cross-correlations between these mortality types we found in 4 of 5 countries studied suggest that seasonal factors broadly and inversely moderate risks for circulatory disease-related mortality and suicide, but not in all regions, indicating that the effect is not uniform. Since the seasonal factors of temperature and light exert opposite effects on suicide and circulatory disease-related mortality in several countries, we propose that physiologically-adaptive circulatory system responses to heat and light may increase risk for suicide and should be studied to determine whether they affect suicide risk. For example, heat and light increase production and release of the bioactive gas nitric oxide and reduce circulatory system disease by relaxing blood vessel tone, while elevated nitric oxide levels are associated with suicidal behavior, inverse effects that parallel the inverse temporal mortality patterns we detected.
全球每年有近 80 万人自杀，自杀率的增长速度超过了人口增长率。不幸的是，自杀的病理生理学仍然知之甚少，这阻碍了自杀预防工作的开展。然而，通过研究季节性对自杀和其他死亡原因的影响，可能会发现机制线索。自杀倾向于在春夏两季达到高峰，在秋冬两季达到低谷，而循环系统疾病相关死亡率则呈现相反的时间趋势。本研究旨在首次确定在人群水平上，自杀和循环系统疾病相关死亡率是否存在月度时间交叉相关性。如果存在这种相关性，如果共同的生物因素调节这两种死亡率类型的风险，那么这些因素可能是可以发现和利用的，以改善自杀预防。
我们对 2009 年至 2018 年期间来自北半球（英国和威尔士、韩国、美国）和南半球（澳大利亚、巴西）国家的月度死亡率数据进行了时间序列分析（共 4180 万例全因死亡率病例）。我们使用泊松回归变异的标准余弦模型来确定死亡率的高峰月份。我们还估计了自杀和循环系统疾病的月度死亡率计数之间的交叉相关性。
在澳大利亚（-0.32）、巴西（-0.57）、韩国（-0.32）和美国（-0.66），自杀和循环系统疾病相关死亡率的时间模式呈负相关，但在英国和威尔士没有发现时间相关性。
我们在 5 个研究国家中的 4 个国家发现这些死亡率类型之间存在负时间交叉相关性，这表明季节性因素广泛且反向调节循环系统疾病相关死亡率和自杀的风险，但并非在所有地区都如此，这表明这种影响并非一致。由于温度和光照的季节性因素对几个国家的自杀和循环系统疾病相关死亡率产生相反的影响，我们提出，对热和光的生理适应性循环系统反应可能会增加自杀的风险，应该进行研究以确定它们是否会影响自杀风险。例如，热和光通过放松血管张力增加生物活性气体一氧化氮的产生和释放，并减少循环系统疾病，而升高的一氧化氮水平与自杀行为有关，这种相反的影响与我们检测到的相反的时间死亡率模式平行。
