The Mexican Cycle of Suicide: A National Analysis of Seasonality, 2000-2013

Abstract

Introduction: Suicide is a complex and multifactorial phenomenon with growing importance to public health. An increase in its occurrence has been observed in Mexico over the past 10 years. The present article analyzes the secular trend in suicide at the national level between the years 2000 and 2013.

Materials and methods: All suicides during the study period (n = 64,298, of which 82.11% were men) were characterized using a spectral decomposition of the time series and a wavelet analysis to evaluate the effect of seasonal changes, type of area (urban versus rural) and sex.

Results: A seasonal pattern was observed with statistically significant cycles every 12 months, where peaks were identified in May but only for men in urban zones as of the year 2007. In addition, specific days of the year were found to have a higher frequency of suicides, which coincided with holidays (New Year, Mother's Day, Mexican Independence Day and Christmas).

Conclusion: A wavelet analysis can be used to decompose complex time series. To the best of our knowledge, this is the first application of this technique to the study of suicides in developing countries. This analysis enabled identifying a seasonal pattern among urban men in Mexico. The identification of seasonal patterns can help to create primary prevention strategies, increase the dissemination of crisis intervention strategies and promote mental health. These strategies could be emphasized during specific periods of the year and directed towards profiles with a higher risk.

Fig 1. Annual Trend in the National Suicide Rate in Mexico, per sex, 2000–2013.

Fig 2. Partial Autocorrelations for the Time Series for Men (above) and Women (below) 2000–2013.

Fig 3. Time Series for National Suicides for Men in Mexico and the Respective Wavelet Power Spectrum, 2000–2013*

Fig 4. Time Series for National Suicides for Women in Mexico and the Respective Wavelet Power Spectrum, 2000–2013

Fig 5. Distribution of the number of suicides among men per month in Mexico from 2000 to 2013 and from 2007 to 2013.

Fig 6. Wavelet Power Spectrum for the Time Series of Suicides for Men in the Urban (right) and Rural Areas (left). (Only as of 2002 due to a lack of data from previous years.)

Fig 7. Wavelet Power Spectrum for the Time Series of Suicides per Mechanism, 2000–2013.

*. * “A” represents suicide by hanging, asphyxiation or strangling, “B” by firearms and “C” by poisoning. “D” is all suicides without differentiating among the mechanisms used.

Fig 8. Distribution of Suicides in Mexico According to Day of the Year, 2000–2013*.

* Differences are significant for each year and for all the years (p<0.05), using the Kruskal-Wallis Test, for each day versus any of the other days.