Abstract
Summary: The problem of the time distribution of suicide has aroused the interest of many authors, but their findings often appear uncertain and contradictory. These inconsistencies can be partially explained by both the choice of the sample and the statistical method used for the analysis. In this study, in order to reveal expected and unexpected periodicities in the time distribution of suicides, we analyzed a small but complete and very homogeneous sample of suicides which occurred in the Mountain District of the Metauro River Valley in Italy in the period 1960-1994. A recent circular statistics technique, the “maximization of mean vector length” was used. We found no significant weekly and lunar patterns, but significant seasonal and intraseasonal cycles, with peaks in March and at the beginning of each season. The superposition of these two significant cyclic trends was also studied.
References
, Seasonal and weather factors in parasuicide.. British Journal of Psychiatry, (1994). 165, 375–380
Epidemiology and chronorhythmicity of recurrences of attempted suicide.. Recenti Progressi in Medicina, (1998). 89, 114–117
Seasonal patterns of suicide, depression and electroconvulsive therapy.. British Journal of Psychiatry, (1976). 129, 472–475
Seasonal variation of suicide in South Africa.. Psychiatry Research, (1997). 66, 13–22
When promises fail: A theory of temporal fluctuations in suicide.. Social Forces, (1988). 67, 129–145
Meteotrope Aktivität der Wetterlage und ihre Rolle in der Selbstmord-Epidemiologie. I. Mitteilung ‘Meteotropic activity of climatic factors and their role in suicide epidemiology. I. Communication’.. Zentralblatt für Bakteriologie, (1975). 161, 158–164
Suicides and the lunar cycles.. Psychological Reports, (1997). 80, 243–250
Zur Epidemiologie von Selbstmordversuchen ‘On the epidemiology of parasuicides’.. Zeitschrift für die Gesamte Innere Medizin und ihre Grenzgebiete, (1991). 46, 654–656
Lunar association with suicide.. Suicide and Life-Threatening Behavior, (1977). 7, 31–39
Temporal variation in suicide and homicide.. American Journal of Epidemiology, (1979). 109, 517–520
Short-term temporal cycles in the frequency of suicide, United States, 1972-1978.. American Journal of Epidemiology, (1983). 117, 744–750
Synchronized annual rhythms in violent suicide rate, ambient temperature and the light-dark span.. Acta Psychiatrica Scandinavica, (1994). 90, 391–396
Seasonal variation in plasma L-tryptophan availability in healthy volunteers. Relationships to violent suicide occurrence.. Archives of General Psychiatry, (1995). 52, 937–946
Variation in suicide occurrence by time of day, day of the week, month and lunar phase.. Suicide and Life-Threatening Behavior, (1991). 21, 174–187
Reports of the cancer registry of the USL 5 of Urbino (Vol. VII).. Bologna: Cantelli Editore (1996).
Suicide and lunar cycles: a critical review over 28 years.. Psychological Reports, (1994). 71, 787–795
The monthly and weekly distribution of suicide.. Social Science and Medicine, (1985). 21, 433– 441
Attempted suicide and the lunar cycle.. Psychological Reports, (1991). 68, 927–930
A sex difference in the seasonal variation of suicide rate: A single cycle for men, two cycles for women.. British Journal of Psychiatry, (1981). 138, 321–325
The bi-seasonal incidence of some suicides.. Experience from Finland by marital status,, (1961-). 976. Acta Psychiatrica Scandinavica 1983; 67, 32–42
Seasonal rhythm of platelet ‘3H’imipramine binding in adolescents who attempted suicide.. American Journal of Psychiatry, (1995). 152, 923–925
The influence of seasonal change on suicidal behaviour in Italy.. Journal of Affective Disorders, (1997). 44, 123–130
The influence of climate on suicidal behaviour in Italy.. Psychiatry Research, (1998). 78, 9–19
Seasonality in suicides: the influence of suicide method, gender and age on suicide distribution in Italy.. Psychiatry Research, (1998). 81, 219–231
On the problem of random vibrations, and of random flights in one, two or three dimensions.. Philosophical Magazine, (1919). 37, 321–347
A circular statistics tool for the preliminary identification of unknown periods in biological rhythms: An application.. Biological Rhythm Research, (1999). 30, 563–72
Intraseasonal pattern in the time distribution of suicides.. Crisis, (2000). 21, 95–97
Nonparametric density estimates for circular data. A new routine and an application to synodic distribution of deliveries.. Studi Urbinati-Facoltà di Farmacia, (1995). 37, 67–75
Suicide in the Canary Islands, 1977- 1983.. Acta Psychiatrica Scandinavica, (1991). 84, 520–523
Seasonality of suicides: Environmental, sociological and biological covariations.. Journal of Affective Disorders, (1987). 13, 215–225
Temporal disappointment, homicide and suicide: an analysis of whites and nonwhites.. Sociological Focus, (1995). 28, 313–328
Analisi della distribuzione temporale dei suicidi. Note metodologiche relative al confronto tra la data di morte e la data dell'atto suicida ‘Analysis of time distribution of suicides. Methodological notes regarding the comparison between death rate and suicide act date’.. Epidemiologia & Prevenzione, (1990). 42, 23–29
Suicides in California (1968-1977): Absence of seasonality in Los Angeles and Sacramento counties.. Psychiatry Research, (1994). 53, 161–172
Variazioni stagionali delle morti per suicidio ‘Seasonal variation of suicide death’.. Rivista Sperimentale di Freniatria, (1988). 112, 1423–1429
Apercus de Dordogne, et de la lune, sur le suicide ‘Views from Dordogne, and the moon, on suicide’.. Encephale, (1996). 22, 52–57
Seasonal variation of suicide and depression.. Archives of General Psychiatry, (1974). 30, 89–91