Heavy Cofee Drinking and the Risk of Suicide
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Heavy coee drinking and the risk of suicide A. Tanskanen 1 , J. Tuomilehto 2 , H. Viinama¨ki 1 , E. Vartiainen 2 , J. Lehtonen 1 & P. Puska 2 1 Department of Psychiatry, University of Kuopio, Kuopio, Finland; 2 National Public Health Institute, Helsinki, Finland Accepted in revised form 3 October 2000 Abstract. Earlier research has implicated coee drinking as a possible protective factor for suicide. We followed-up 43,166 subjects for the mean 14.6 years, and 213 suicides were committed. Daily coee drinking had a J-shaped association with the risk of suicide. Using the Cox model we controlled for potential covariates, and found that among heavy coee drinkers (P8 cups/day) the risk of suicide was 58% higher compared with more moderate drinkers. Key words: Coee, Mortality, Risk, Suicide Introduction A significant inverse association has been previously reported between coee drinking and the risk of suicide [1, 2]. This protective eect has been attrib- uted to caeine that is a central nervous system stimulant [3]. However, both the suicide rate and the coee drinking level in the populations of these studies were low. According to trade statistics, the average annual consumption of coee per capita in Finland was 12.4 kg (corresponding to 4 cups/day) in 1994, which is the highest amount in the world. The suicide rate of the Finns is also high internationally, and the rate has constantly increased during the recent decades [4]. Therefore, we considered it important to analyze the association between coee drinking and the risk of suicide in the Finnish population using prospective data from large cohorts with a long follow-up. Material and methods Five independent population surveys (1972, 1977, 1982, 1987, 1992) have assessed the levels of risk factors for coronary heart disease in eastern, south- western and southern Finland. For each survey, an independent random sample of subjects aged 25– 64 years was drawn from the National Population Register. The participation rates varied from 69 to 96% by survey year, gender, and area. There were 20,995 male and 22,171 female subjects available for the present analyses. Briefly, the surveys included a self-administered questionnaire (mainly questions on socioeconomic factors, medical history, health be- havior and psychosocial factors) and measurements of height, weight and blood pressure. Details of the survey procedures have been described earlier [5]. All the study procedures were carried out in accordance with the ethical standards of the Helsinki Declaration of the World Medical Association. The subjects were followed until 31 December 1995, or death. The mean follow-up was 14.6 (range 1–24) years. Information on deaths caused by suicide was obtained from the National Death Register. The end points were the codes E950–E959 of the Inter- national Classification of Diseases (ICD). The eighth revision of ICD was used from 1972 to 1986, and the ninth revision was adopted from the beginning of 1987. The amount of coee drinking was determined with an open question: How many cups of coee do you usually drink daily. The daily coee use was classified into six categories (0–1, 2–3, 4–5, 6–7, 8–9 and 10 or more cups/day) in the first analysis. Subsequently, the coee drinking variable was dichotomized to light/moderate level of drinking (0–7 cups/day), and to heavy (P8 cups/day) drinking for the multivariate analysis. In the Cox proportional hazards regression model, the multivariate relative risk of suicide was controlled for potential covariates like gender, age, marital sta- tus, education, employment status, smoking, alcohol consumption, tea drinking, and body-mass index. The subjects with feelings of depression, anxiety, phobia, or psychosocial stress, and with current psychotropic medication at baseline were excluded from the final analysis. Results Eight percent of the study subjects were drinking 0–1, 19% 2–3, 30% 4–5, 26% 6–7, 9% 8–9 and 8% 10 or more cups of coee daily at baseline. During the follow-up there were 213 suicides, and the number of suicides in the six coee drinking categories were 19, 29, 56, 48, 28 and 33, respectively. European Journal of Epidemiology 16: 789–791, 2000. Ó 2001 Kluwer Academic Publishers. Printed in the Netherlands.
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Transcript of Heavy Cofee Drinking and the Risk of Suicide
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Heavy coee drinking and the risk of suicide
A. Tanskanen1, J. Tuomilehto2, H. Viinamaki1, E. Vartiainen2, J. Lehtonen1 & P. Puska21Department of Psychiatry, University of Kuopio, Kuopio, Finland; 2National Public Health Institute, Helsinki, Finland
Accepted in revised form 3 October 2000
Abstract. Earlier research has implicated coeedrinking as a possible protective factor for suicide.We followed-up 43,166 subjects for the mean14.6 years, and 213 suicides were committed. Dailycoee drinking had a J-shaped association with the
risk of suicide. Using the Cox model we controlledfor potential covariates, and found that among heavycoee drinkers (P8 cups/day) the risk of suicide was58% higher compared with more moderate drinkers.
Key words: Coee, Mortality, Risk, Suicide
Introduction
A significant inverse association has been previouslyreported between coee drinking and the risk ofsuicide [1, 2]. This protective eect has been attrib-uted to caeine that is a central nervous systemstimulant [3]. However, both the suicide rate and thecoee drinking level in the populations of thesestudies were low. According to trade statistics, theaverage annual consumption of coee per capita inFinland was 12.4 kg (corresponding to 4 cups/day) in1994, which is the highest amount in the world. Thesuicide rate of the Finns is also high internationally,and the rate has constantly increased during therecent decades [4].Therefore, we considered it important to analyze
the association between coee drinking and the riskof suicide in the Finnish population using prospectivedata from large cohorts with a long follow-up.
Material and methods
Five independent population surveys (1972, 1977,1982, 1987, 1992) have assessed the levels of riskfactors for coronary heart disease in eastern, south-western and southern Finland. For each survey, anindependent random sample of subjects aged 2564 years was drawn from the National PopulationRegister. The participation rates varied from 69 to96% by survey year, gender, and area. There were20,995 male and 22,171 female subjects available forthe present analyses. Briefly, the surveys included aself-administered questionnaire (mainly questions onsocioeconomic factors, medical history, health be-havior and psychosocial factors) and measurementsof height, weight and blood pressure. Details of thesurvey procedures have been described earlier [5]. Allthe study procedures were carried out in accordance
with the ethical standards of the Helsinki Declarationof the World Medical Association.The subjects were followed until 31 December
1995, or death. The mean follow-up was 14.6 (range124) years. Information on deaths caused by suicidewas obtained from the National Death Register. Theend points were the codes E950E959 of the Inter-national Classification of Diseases (ICD). The eighthrevision of ICD was used from 1972 to 1986, and theninth revision was adopted from the beginning of1987.The amount of coee drinking was determined
with an open question: How many cups of coee doyou usually drink daily. The daily coee use wasclassified into six categories (01, 23, 45, 67, 89and 10 or more cups/day) in the first analysis.Subsequently, the coee drinking variable wasdichotomized to light/moderate level of drinking(07 cups/day), and to heavy (P8 cups/day) drinkingfor the multivariate analysis.In the Cox proportional hazards regression model,
the multivariate relative risk of suicide was controlledfor potential covariates like gender, age, marital sta-tus, education, employment status, smoking, alcoholconsumption, tea drinking, and body-mass index.The subjects with feelings of depression, anxiety,phobia, or psychosocial stress, and with currentpsychotropic medication at baseline were excludedfrom the final analysis.
Results
Eight percent of the study subjects were drinking 01,19% 23, 30% 45, 26% 67, 9% 89 and 8% 10 ormore cups of coee daily at baseline. During thefollow-up there were 213 suicides, and the number ofsuicides in the six coee drinking categories were 19,29, 56, 48, 28 and 33, respectively.
European Journal of Epidemiology 16: 789791, 2000. 2001 Kluwer Academic Publishers. Printed in the Netherlands.
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Daily coee drinking had a J-shaped associationwith the risk of suicide (Figure 1). The age-adjustedrisks (with 95% CIs) of suicide were 1.00, 0.67 (0.381.20), 0.82 (0.481.37), 0.82 (0.481.39), 1.32 (0.742.37) and 1.69 (0.962.98), in the six coee drinkingcategories, respectively.In the Cox proportional hazards regression model
including the potential covariates, heavy coeedrinking was significantly associated with mortalityfrom suicide (Table 1). There was a 58% higher rel-ative risk (RR: 1.58, 95% CIs: 1.022.42; p 0.039)of suicide among heavy (P8 cups/day) coee drink-ers compared with more moderate drinkers.
Discussion
Our results suggest that heavy coee drinking may bean independent risk factor for suicide, and the asso-ciation seems to be J-shaped, moderate drinkershaving the lowest risk. These results dier from pre-vious assertions that coee drinking might be a pro-tective factor for suicide [1, 2]. In the previous studiesthe highest coee drinking categories were six [1], andfour [2] or more cups of coee per day. Consequently,the earlier studies did not evaluate the risk of suicidein really heavy (excessive) coee users at all. TheFinns are a population, in which both the suicide rate
Table 1. Adjusted RR of potential risk factors for suicide calculated by the Cox proportional hazardsregression model*
Variable RR 95% CIs p-value
Male gender 4.77 2.698.44 0.0001
Unemployment 3.50 1.597.67 0.002Single, divorced or widowed 1.74 1.152.63 0.009Current smoking 1.65 1.092.48 0.017
Heavy coee drinking (P8 cups/day) 1.58 1.022.42 0.039Heavy alcohol consumption (>120 g/week) 1.37 0.842.23 0.21Low education (
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and the mean level of coee drinking are clearlyhigher than those in the USA, where the earlierstudies have been carried out. In addition, the con-centration of coee in Finland is known to bestronger than that usually consumed in the USA. It ispossible that these facts explain the discrepancy be-tween our results and the previous findings.We were unable to calculate the total caeine in-
take, and this is a limitation of our study. However,the use of soft drinks containing caeine is infrequentamong adults in Finland, so it would have not con-tributed much to the total caeine intake after all. Allinformation was gathered at only one point in time,at baseline. So any changes in coee use, any otherrisk factor, or in life circumstances generally mighthave altered the coeesuicide relationship. However,this is the limitation in most of the long-term pro-spective studies.Caeine is an addictive psychoactive substance,
and heavy caeine use is influenced by genetic factors[6]. It increases nervousness, fear, tension, palpita-tions, restlessness, tremors, and may induce subject-rated anxiety and panic attacks in sensitive normalsubjects [7]. Acute intake of large amounts of caeinemay increase psychoses and hostility [8]. The plausi-ble mechanism by which excessive coee drinkingincreases the risk of suicide remains to be revealed.The association observed may have arisen becauseexcessive coee drinking (i.e. caeine abuse) may becorrelated with one or more third factors predis-posing to the mental state (e.g. personality disorder)that raises the risk of suicide.In conclusion, there is now new evidence that ex-
cessive coee drinking may be hazardous to mentalhealth. Nowadays psychiatric researchers are urged to
routinely screen for and control the use of caeine [9].Perhaps it is time also for clinicians to do the same.
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Address for correspondence: Dr Antti Tanskanen, Depart-
ment of Psychiatry, University of Kuopio P.O. Box 1777,70211 Kuopio, FinlandPhone: 358-17-173546; Fax: 358-17-173549
E-mail: [email protected]
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