Decreasing tendency of seasonality in suicide may indicate lowering rate of depressive suicides in the population (original) (raw)

Seasonality of suicides with and without psychiatric illness in Denmark

Journal of Affective Disorders, 2006

This paper studied the seasonality of suicides among persons with and without psychiatric illness in Denmark from 1970 to 1999. A non-homogenous Poisson process was used to examine the data. The seasonality of suicides was shown to be associated with gender and their psychiatric histories with a declining trend of suicide incidence noted over the captured period. A mild seasonal component was reported in the period of the late 70s to early 80s (1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984) among females who did not have any psychiatric treatment history, while in the 80s the significant seasonality was mainly contributed by male suicides without a psychiatric history. Another mild possible invoked seasonality in the 90s was in males who suffered from psychiatric illness. The rest could be treated as random events. Apparently, the seasonality among suicides with psychiatric illness exists but its effect could vary in different periods of time and among genders in Denmark.

Seasonality of suicide in Sweden: Relationship with psychiatric disorder

Journal of Affective Disorders, 2009

Background: Little is known as to whether suicide seasonality is related to psychiatric disorders affecting suicide risk/incidence. The present study aims to assess suicide seasonality patterns with regard to the history of psychiatric morbidity among suicide victims.

Use of Statistical Techniques in Studies of Suicide Seasonality, 1970 to 1997

Suicide and Life-Threatening Behavior, 2002

The effect of seasons on suicides has been suggested repeatedly. In order to reveal a true seasonal pattern, an appropriate statistical technique, which is sensitive to a specific type of cyclic variation in the data, must be chosen. This study is a review of the use of statistical techniques for seasonality and of some important characteristics of study samples that were evaluated from 46 original suicide seasonality articles published in major psychiatric journals. The results showed that statistical techniques were applied in a majority of articles, but they were commonly lacking regarding analyses, which compared seasonal patterns among subgroups of a population. In recent studies more sophisticated statistical techniques were utilized for seasonality, like spectral analyses, as compared with earlier studies, in which the emphasis was on chi-square tests. Lack of reporting essential features of the data, such as the sample size and monthly values of suicides, were frequent. The calendar effect was adjusted only in 11 studies. Some recommendations concerning the methodological and reporting issues are summarized for future articles on the seasonal affect on suicides.

Seasonal variation in suicide occurrence in Finland

Acta Psychiatrica Scandinavica, 1998

The aim of this study was to investigate the age-, gender- and suicide method-related seasonality of suicide occurrence by using the largest database examined so far (n=21,279). The Chi-square test for multinomials was used as the overall measure of deviation. The monthly observed and expected numbers of suicides were calculated and classified by year, month, gender, age groups and suicide methods. To identify the statistically significant peak and trough months, the ratio of observed numbers of suicides to expected numbers with 95% confidence intervals was calculated. For males, there was a suicide peak from April to July, while for females the distribution was bimodal (with peaks in May and October). In elderly people there was a significant excess in the number of suicides in autumn, and the troughs were deeper in winter. For violent suicides there was a unimodal spring peak, but for non-violent suicides the distribution was bimodal. The results indicate that suicides among elderly subjects, as well as non-violent suicides, occur significantly more often during autumn than would be expected.

Suicide and seasonality

• The study of suicide seasonality is one of the parameters that could contribute in suicide prevention.

Seasonality of suicide: a multi-country multi-community observational study

Epidemiology and Psychiatric Sciences, 2020

Aims We aimed to investigate the heterogeneity of seasonal suicide patterns among multiple geographically, demographically and socioeconomically diverse populations. Methods Weekly time-series data of suicide counts for 354 communities in 12 countries during 1986–2016 were analysed. Two-stage analysis was performed. In the first stage, a generalised linear model, including cyclic splines, was used to estimate seasonal patterns of suicide for each community. In the second stage, the community-specific seasonal patterns were combined for each country using meta-regression. In addition, the community-specific seasonal patterns were regressed onto community-level socioeconomic, demographic and environmental indicators using meta-regression. Results We observed seasonal patterns in suicide, with the counts peaking in spring and declining to a trough in winter in most of the countries. However, the shape of seasonal patterns varied among countries from bimodal to unimodal seasonality. The...

Seasonality of Suicidal Behavior

International Journal of Environmental Research and Public Health, 2012

A seasonal suicide peak in spring is highly replicated, but its specific cause is unknown. We reviewed the literature on suicide risk factors which can be associated with seasonal variation of suicide rates, assessing published articles from 1979 to 2011. Such risk factors include environmental determinants, including physical, chemical, and biological factors. We also summarized the influence of potential demographic and clinical characteristics such as age, gender, month of birth, socioeconomic status, methods of prior suicide attempt, and comorbid psychiatric and medical diseases. Comprehensive evaluation of risk factors which could be linked to the seasonal variation in suicide is important, not only to identify the major driving force for the seasonality of suicide, but also could lead to better suicide prevention in general.

Seasonality and time-related aspects of suicides in Greece: an applied time-series analysis

Dialogues in Clinical Neuroscience & Mental Health, 2019

The background that underlies each committed suicide varies among people and constitutes a complex structure of psychological , behavioural and biological risk factors that may be triggered by external conditions. Recent studies have shed new light on the association of suicides with particular days and periods of year, in an attempt to resolve the inconsistencies met in literature regarding this relationship. The aim of this study is to look into any time-related patterns on suicides in Greece and to do so we analyzed the frequency of suicides over a period of 13 years (2000-2012) in terms of day of the week, month, major celebration and season. A seasonal ARIMA model revealed the association between suicide frequency and month of year, with a peak to be reached in May and July and increased numbers of suicides to be reported during spring and summer months. Monday was the most frequent day of suicide occurrence whereas Sunday was the least one. A season pattern of suicides was validated. The increase of suicide occurrences on Mondays could be explained by the "broken-promise effect" which has been described as the consequence of frustrated expectations of the weekend. Suicide peaks in spring and summer may be explained partially by biological factors (e.g. serotonergic alterations) as well as the experience of depressed people perceiving the social and emotional contrast to other people that enjoy outdoor activities at that period.