Electronic Letters to:
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eLetters: Electronic letters published:
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Age Specific Data Analysis is Needed
- Leonid A. Gavrilov, Ph.D., Natalia S. Gavrilova, Ph.D. (4 May 2006)
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Effect of Month of Birth on the Risk of Suicide. Role of Mood Variation.
- Angelo Cagnacci (9 May 2006)
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Season of birth effects and developmental vitamin D
- John J McGrath, Darryl Eyles, Thomas Burne (19 May 2006)
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Month of birth in relation to suicide
- Jayanti Chotai (19 May 2006)
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The effects of month of birth and geographical latitude on risk of suicide and related disorders
- Piet H Jongbloet (15 February 2007)
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Re: The effects of month of birth and geographical latitude on risk of suicide and related disorders
- Emad Salib (9 March 2007)
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Leonid A. Gavrilov, Ph.D., Scientist Center on Aging, NORC/University of Chicago, Natalia S. Gavrilova, Ph.D.
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gavrilov{at}longevity-science.org Leonid A. Gavrilov, Ph.D., et al.
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It may be interesting to reanalyze the data of this new published study for specific age groups (say 20-24, 25-29 and 30-34 years, etc.), to see whether the month-of-birth effect on suicides still remains to exist. This is an important issue, because the number of people surviving to certain age also depends on the month of birth (Gavrilov & Gavrilova, 1999; 2003; 2004; Gavrilova et al, 2003; Gavrilova & Gavrilov, 2005). Thus the exposure to risk of suicide (denominator numbers) depends on the month of birth in a complex age-specific manner, and these exposure data could not be simply estimated from the seasonality of births. REFERENCES Gavrilov, L.A. & Gavrilova, N.S. (1999) Season of birth and human longevity. Journal of Anti-Aging Medicine, 1999, 2(4): 365-366. Gavrilov, L.A. & Gavrilova, N.S. (2003) Early-life factors modulating lifespan. In: Rattan, S.I.S. (Ed.).Modulating Aging and Longevity. Kluwer Academic Publishers, Dordrecht, The Netherlands, 27-50. Gavrilova N.S., Gavrilov L.A., Evdokushkina, et al., (2003) Early- life predictors of human longevity: Analysis of the 19th Century birth cohorts. Annales de Demographie Historique, 2: 177-198. Gavrilov, L.A. & Gavrilova, N.S. (2004) Early-life programming of aging and longevity: The idea of high initial damage load (the HIDL hypothesis). Annals of the New York Academy of Sciences, 1019, 496-501. Gavrilova, N.S. & Gavrilov, L.A. (2005) Search for Predictors of Exceptional Human Longevity. In: “Living to 100 and Beyond” Monograph. The Society of Actuaries, Schaumburg, Illinois, USA, pp. 1-49. Published online at: http://library.soa.org/library-pdf/m-li05-1_V.pdf |
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Angelo Cagnacci, Associate Professor Ob/Gyn Policlinico of Modena
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cagnacci{at}unimore.it Angelo Cagnacci
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I read with great interest the article by Salib &Cortina-Boria (1). At the end of their discussion the authors suggest that “the month of birth factor in suicide may reflect individual’s constitutional vulnerability and affective predisposition” . We recently obtained data in support of this hypothesis. In a multicentric study, by evaluating the psychological status of 2581 Italian women in postmenopause, we showed that anxiety and depression are minimal in women born in Autumn (lowest value November) and peak in women born in Spring (maximal value in March) (2). This seems to reflect quite nicely the seasonal pattern of suicide reported by Salib &Cortina- Boria (1). In our study, data were corrected for the month into which the psychological evaluation was indeed performed. Mood varies throughout the year, and seasonal rhythms of suicide (3,4), or of events related to low mood, as voluntary abortion, have been reported (4). Interestingly, these rhythms are similar to the one reported by Salib & Cortina-Boria for the month of birth and risk of suicide(1). It would be interesting to see whether data of this latter study would remain significant when corrected for the seasonal rhythm of suicide. If this is the case, the concordance between the seasonal rhythm of suicide, and the predisposition to suicide at birth, would suggest that the mechanisms predisposing the newborn to the risk of suicide are operative in the last part of pregnancy, very close to the timing of delivery. 1. Salib, E. & Cortina-Borja, M. (2006) Effect of month of birth on the risk of suicide. British Journal of Psychiatry, 188, 416-422. 2. Cagnacci, A., Pansini, F.S., Bacchi-Modena, A., Volpe, A. (2006) The relation of season of birth to severity of menopausal symptoms. Menopause, 13, in press 3. Maes, M., Meltzer, H.Y., Suy, E., et al. (1993) Seasonality in severity of depression:relationships to suicide and homicide occurrence. Acta Psychiatrica Scandinavica, 88, 156-161. 4. Cagnacci, A. & Volpe, A. (2001) Is voluntary abortion a seasonal disorder of mood? Human Reproduction, 16, 1748-1752. |
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John J McGrath, Psychiatrist University of Queensland, Darryl Eyles, Thomas Burne
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john_mcgrath{at}qcsr.uq.edu.au John J McGrath, et al.
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Dear Sir, The paper by Salib and Cortina-Borja contributes further evidence demonstrating that seasonally-fluctuating early-life exposures influence a surprisingly diverse range of adult health outcomes. However, the question for the research community is no longer “Does season of birth influence health outcomes?” We have known the answer to this question for decades. We must avoid falling into the trap of ‘circular epidemiology’, where oft- replicated ecological findings fail to move from ecological to analytical studies (Kuller, 1999). The task for the research community can be summarized in three steps. Firstly, specific candidate exposures need to be proposed. Secondly, the biological plausibility of these candidates with respect to particular health outcomes needs to be examined, mostly in animal models (e.g. does prenatal exposure to a certain biological agent alter brain development in a fashion that is relevant to depression and/or suicide). Thirdly, the candidate exposure needs to be directly measured in analytical studies that link individual-level exposure with the health outcome. Salib and Cortina-Borja propose developmental candidates such as melatonin, serotonin and cortisol. Our group has focused on vitamin D as a candidate exposure underpinning risk of schizophrenia (maternal, and thus fetal, vitamin D levels fluctuate across the seasons). The readers may be interested to learn that there is now robust evidence from animal experiments (rats) demonstrating that developmental vitamin D deficiency is associated with altered adult brain outcomes (e.g. increased ventricles, altered neurotrophin levels, altered behaviour) (Becker, Eyles, McGrath, et al, 2005; Burne, Becker, Brown, et al, 2004; Feron, Burne, Brown, et al, 2005; Kesby, Burne, McGrath, et al, in press). Researchers interested in season-of-birth effects might like to include developmental vitamin D as a biologically-plausible, seasonally- fluctuating candidate exposure. John McGrath Darryl Eyles Thomas Burne Becker, A., Eyles, D. W., McGrath, J. J., et al (2005) Transient prenatal vitamin D deficiency is associated with subtle alterations in learning and memory functions in adult rats. Behav Brain Res, 161, 306- 312. Burne, T. H., Becker, A., Brown, J., et al (2004) Transient prenatal Vitamin D deficiency is associated with hyperlocomotion in adult rats. Behav Brain Res, 154, 549-555. Feron, F., Burne, T. H., Brown, J., et al (2005) Developmental Vitamin D3 deficiency alters the adult rat brain. Brain Res Bull, 65, 141-148. Kesby, J., Burne, T. H., McGrath, J. J., et al (in press) Developmental vitamin D deficiency is associated with MK 801-induced hyperlocomotion in the adult rat: an informative animal model of schizophrenia. Biological Psychiatry. Kuller, L. H. (1999) Circular epidemiology. Am J Epidemiol., 150, 897-903. |
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Jayanti Chotai, MD, PhD, Assoc Professor Division of Psychiatry, Dept of Clinical Sciences, University Hospital, 901 85 Umeå, Sweden.
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jayanti.chotai{at}vll.se Jayanti Chotai
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In their interesting and thorough article, Salib & Cortina-Borja (2006) find that persons born during the spring-summer season of April, May and June were significantly more likely to commit suicide compared to those born during other months. They find a peak for the birth month May and a trough for October. However, they misreport our earlier results in this field when they state in the introduction that ”Chotai et al (1999) reported that people born in winter in Sweden were significantly more likely than those with other birth seasons to have used hanging as a suicide method.” They further misreport other earlier findings of ours when they state in the discussion that ”However, winter variations in serotonin reported by Chotai & Åsberg (1999) are inconsistent with the findings of this study, essentially the opposite of the Swedish findings.” Contrary to these statements of Salib & Cortina-Borja (2006), our earlier findings are in fact similar to and consistent with their results. In Chotai et al (1999), we clearly show and state that those who preferred hanging rather than poisoning or petrol gases were significantly more likely born during February to April. In Chotai & Åsberg (1999) we clearly show and state that those born during February to April had significanly lower 5-HIAA (5-hydroindoleacetic acid). We have also published cosinor analyses of our data (Chotai & Adolfsson, 2002), where we found that the minimum of the month-of-birth curve for 5-HIAA was obtained for the birth month April (t-min 3.4 in Table 1 of that paper, where the interval 3-4 depicts April), and the maximum was obtained for October (t-max 9.4). We also report there that the maximum of the month-of-birth curve for preferring hanging was for March-April and the minimum was for September-October. Low serotonin turnover has been implicated as a risk factor for suicidal behaviour, particularly with violent or lethal methods of suicide, as discussed by Salib & Cortina-Borja (2006). Thus our findings are in line with those of Salib & Cortina-Borja (2006) regarding suicidality, since we obtained a peak for the birth month April comparable to their peak for May, and our findings are consistent with theirs since we found a trough for 5-HIAA for the birth month April. In another epidemiological study (Chotai & Salander Renberg, 2002), we report that the season of birth associations with the suicide methods were found in those without a history of psychiatric contacts, but not in those with. We have argued that season of birth associations for suicide methods are likely to be mediated to a large extent by a suicidality trait independently of specific major psychiatric disorders, with serotonin as the likely underlying neurotransmitter. In our studies, the season of birth variation was found for hanging as the suicide method, but not for other methods often denoted as violent together with hanging, for example firearms or drowning. Hanging is a more universal method of suicide, and gender differences in the proportion of hanging are much lower than for the other methods. In this light, it would be of interest to analyse the data of Salib & Cortina-Borja (2006) specifically regarding whether there is a month of birth variation in suicide by hanging. REFERENCES Chotai J, Adolfsson R (2002) Converging evidence suggests that monoamine neurotransmitter turnover in human adults is associated with their season of birth. European Archives of Psychiatry and Clinical Neuroscience 252, 130-134. Chotai J, Åsberg M (1999) Variations in CSF monoamine metabolites according to the season of birth. Neuropsychobiology 39, 57-62. Chotai J, Salander Renberg E, Jacobsson L (1999) Season of birth associated with the age and method of suicide. Archives of Suicide Research 5(4), 245-254. Chotai J, Salander Renberg E (2002) Season of birth variations in suicide methods in relation to any history of psychiatric contacts support an independent suicidality trait. Journal of Affective Disorders 69, 69- 81. Salib E, Cortina-Borja M (2006) Effect of month of birth on the risk of suicide. British Journal of Psychiatry 188, 416-422. |
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Piet H Jongbloet, Radboud University Nijmegen Medical Centre, Dept. of Epidemiology and Biostatistics PhD, MD
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P.Jongbloet{at}epib.umcn.nl Piet H Jongbloet
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Salib & Cortina-Borja (2006) describe a disproportional excess of people who kill themselves when born (in early winter and) between late spring and midsummer and a disproportional deficit when born in late autumn. This month of birth effect can be interpreted in the context of another unexplained characteristic, namely the increasing South-North gradient, i.e. the geographical latitude effect, as shown in different countries. Optimal maturation of the oocyte in animals and humans has been forwarded to occur during the prime time of the seasonally-bound ovulatory seasons and to lead to optimal development of the zygote leading to less morbidity during pregnancy, birth and adult age. In contrast, non-optimal maturation would occur during the inherent transitional stages leading to errant early neural migration and/or developmental differentiation (Jongbloet, 1975). This seasonally-bound month of birth effect is recognized in the presented data, particularly in females (violent and non -violent methods) and males (non-violent methods) and in anencephalia, schizophrenia and related diseases, such as eating disorders (Jongbloet et al, 2005). This concept also explains the shorter life expectancy for people born during the first part of the year versus the longer expectancy during the second part, and its mirror image on the Southern hemispere (Dobblhammer & Vaupel, 2001). Seasonality of the ovulatory pattern as cause of month of birth on suicide can easily be connected with the geographical latitude effect. In fact, the consistent relation between timing of mating seasons in different animals and humans causes stronger transitional stages the further discarded from the equator and, thus, higher frequency of non- optimal maturation of the oocytes. This biological phenomenon explains the mentioned geographical latitude effect on suicidality, schizophrenia and congenital anomalies of the nervous system, diverging between both hemisperes. The highly biased tertiary sex ratio in both suicidality and schizophrenia and the different other high-risk factors, such as teenage motherhood, multiparity and intrauterine growth retardation (Mittendorfer-Rutz et al., 2004) are quite well compatible with this concept. This month of birth factor, therefore, does not need to be interpreted in terms of the “foetal origins” hypothesis, nor the “maternal-foetal origins” hypothesis, as suggested by the authors, but rather of the “oocyte origins” hypothesis. Doblhammer, G. & Vaupel, J. W. (2001). Lifespan depends on month of birth. PNAS, 98, 2.934-2.939. Jongbloet, P. H. (1975) The effects of preovulatory overripeness of human eggs on development. In Aging gametes. Their Biology and pathology International Symposium, Seattle 1973 (ed. RJ Blandau), pp. 300-329, Basel: Karger. Jongbloet, P. H., Groenewoud H. M. M. & Roeleveld N. (2005) Seasonally-bound ovopathy versus ‘temperature at conception’ as cause for anorexia nervosa. International Journal of Eating Disorders. 38, 236-243. Mittendorfer-Rutz, E., Rasmussen, F. & Wasserman,D. (2004) Restricted fetal growth and adverse maternal psycholosocial and socioeconomic conditions as risk factors for suicidal behaviour of offspring: a cohort study. Lancet, 364, 1335-1340. Salib, E. & Cortina-Borja, M. (2006) Effect of month of birth on risk of suicide. British Journal of psychiatry, 188, 416-422. |
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Emad Salib, Honorary Senior Lecturer Liverpool University
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esalib{at}hotmail.com Emad Salib
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We are grateful to Piet Hein Jongbloet for introducing us to this fascinating area of biological research. Jongbloet, who has a most impressive record in this field for more than 30 years, provides an alternative explanation of our findings about the effect of month of birth on suicide, which is based on ‘oocyte origins’ hypothesis as opposed to the maternal foetal origin hypothesis. According to the oocyte hypthesis, the intricate interplay between nonoptimal oocyte maturation and genes results in a subtle but complex pathogenesis of the foetal nervous system .. This occurs in well-timed menstrual cycles, but more so in instances of distorted hormonal tuning, not only in deprived socioeconomic conditions but also at the extremes of maternal reproductive life, among endocrinologically unbalanced mothers, after very short pregnancy intervals, during the seasonal transitions of the "ovulatory" seasons, etc (Jongbloet 2001). A similar broad spectrum of male-biased developmental anomalies—low birth weight and length, small stature at school age or adulthood, morbidity, and mortality—is present in all these circumstances (Jongbloet (1985). To illustrate the oocyte hypothesis in practical terms; mothers with low socioeconomic status are known to suffer from more menstrual disorders , low standards of nutrition, and abnormal body mass index (Power & Matthews 1997). They also are more likely to be smokers or drug users (Pierrce et al 1989) and to employ less safe methods of contraception, resulting in more unplanned and unwanted pregnancies, particularly at the extremes of maternal reproductive age and during the postpartum restoration of the ovulatory pattern, ie, after very short interpregnancy intervals. They are likely to have non optimal oocyte maturation, thus rendering the offspring vulnerable to low birth weight and certain psychiatric disorders. However, we are not clear as to how this hypothesis actually differs from the maternal foetal origin hypothesis used to explain our findings (Salib & Cortina Borja 2006). The geographic latitude effect in incidence rate of suicide in England and Wales and elsewhere is assumed by Jongbloet to be a consequence of the stronger seasonal ovulatory pattern the further away from the Equator, just as in animals, and, in turn, stronger transitional stages between the ovulatory seasons and, thus, more poor quality oocytes, The only way to accept or reject this concept is by demonstrating the same increase of suicide incidence rate—and of other disease entities or behaviour of complex origin. Emad Salib Honorary Senior Lecturer, Liverpool University Peasley Cross Hospital, St Helens WA9 3DX esalib@hotmail.com Mario Cortina-Borja Centre for Paediatric Epidemiology and Biostatistics Institute of Child Health, University College London References Jongbloet PH. (1985) The ageing of gamete in relation to birth control failures and Down syndrome. Eur J Pediatr. 1985; 144: 343–347 Jongbloet PH, (2001) Zielhuis GA, Groenewoud HMM, Pasker-de Jong PCM. The secular trends in male: female ratio at birth in postwar industrialized countries. Env Health Perspect. 2001; 109: 749–752. Pierrce JP, Fiore MC, Novotny TE, et al. (1989) Trends in cigarette smoking in the United States. JAMA. 1989; 61: 56–60. Power C, Matthews S. (1997) Origins of health inequalities in a national population sample. Lancet. 1997; 350: 1584–1589. Salib E., Cortina-Borja M (2006) Effect of month of birth on risk of suicide. British Journal of Psychiatry, 188, 416-422 |
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