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Rapid Responses: Rapid Responses published:
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For whom is this study valid?
- Alan Challoner MA (Phil) MChS (21 January 2005)
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Re: For whom is this study valid?
- susanne mccabe (21 January 2005)
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Will it not be a sort of discrimination?
- girish chawla (22 January 2005)
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Disadvantage and male suicide
- Andrew S. Humphreys (22 January 2005)
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A negative association of intelligence and risk of suicide?: short follow up may mask the actual lifetime association
- Martin Voracek (23 January 2005)
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Intelligence score and risk of suicide linked via tryptophan metabolism
- Dietmar Fuchs, Katharina Schroecksnadel, Christiana Winkler (28 January 2005)
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Alan Challoner MA (Phil) MChS, Retired LL18 5UR
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I wonder just how valid is the outcome of the ‘Low intelligence test scores in 18 year old men and risk of suicide: cohort study’, for other perhaps less homogenous groups? [1] Using the Swedish military service conscription register (1968-94) with the multi-generation register, cause of death register and census data, surely restricts outcome to others in a similar group. We were already aware of the impact of environmental episodes on later suicide including important events from childhood. [1] Gunnell, D; Magnusson, P K E; Rasmussen, F. Low intelligence test scores in 18 year old men and risk of suicide: cohort study. BMJ 2005;330:167 (22 January), doi:10.1136/bmj.38310.473565.8F (published 22 December 2004) Competing interests: None declared |
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susanne mccabe, retired cf24 3pf
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If this sort of testing is still going on it raises a number of questions which organisations which represent the interests of those who risk their lives in war, especially those who have historically been used as 'cannon fodder', should address:- are 'conscripts' themselves being properly informed about the tests including the potential uses of data are they being given the right not to take part by declining to join the forces are they given the results of the tests, including the way they are descibes as being of 'low intelligence' if they are perceived to be at risk of suicide are they being advised not to join the forces and given the reason are their relatives being informed of genetic testing is there any consent process which may include living relatives and why are men only being targeted Competing interests: None declared |
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girish chawla, sho surgery worcester royal hospital, WR5 1EP
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Dear Sir, I wonder , what could be the potential results of these sort of studies on the life of many people in the future?. Its a good topic as far as academics is considered but the impact it will have on selection process will be a sort of discrimination without firm evidence. According to my understanding it is probably against medical ethics as when those people with low scores come to know the results that they are more succeptible to commiting sucide, might actually get stressed and it may lead to depression. No one likes to be proved as inferior to someone else and suicide has multifactorial causes so just commenting on the basis of a single criteria of intelligence is not right. I hope that we would consider the consequences of a research and its result on Society as well, as Research is meant to bring happiness in the lives of people rather than discrimination on the basis of genetic make up or intelligence. Kind Regards
Competing interests: None declared |
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Andrew S. Humphreys, Social Worker Milton Hospital NSW 2538
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The rate of male suicide has in Australia and most western countries closely followed rates of economic activity and unemployment. In the 1980's in Victoria (Aust.) I observed dramatic changes to the social health of low income young men in Melbourne, associated with a rapid increase in the suicide rates for younger males in areas of lower av. income. This was precipitated by significant changes to the provision of vocational education (80 free junior technical schools were closed) and secondary schools adopted uniform curricula and assessment tools that advantaged female and middle class pupils. A feature of most of the young men I see 'at risk' is their
difficulties solving the life problems that confront them. These
difficulties are compounded by low education.
In assessing risk for young men I look for the following criteria
Competing interests: None declared |
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Martin Voracek, research resident School of Psychology, University of Vienna, A-1010 Vienna, Austria
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EDITOR––In their cohort study of nearly one million Swedish conscripted men, Gunnell and colleagues [1] reported a negative association between intelligence test score at age 18 and suicide during follow up (5-26 years). Owing to the somewhat selective referencing in this paper, it is probably unapparent for most readers that this evidence is surprising, inasmuch as being contrary to a great many findings from previous related accounts. Research interest on this topic can be traced back to the late 19th century. [2] Reviews [3-5] of the evidence accumulated since then suggest that the association between intelligence and lifetime risk of suicide more probable is positive, not negative. In most Western industrialised nations, including Sweden, there is an exponential age effect in suicide mortality which furthermore is more pronounced for men than for women. [5] This means that the majority of suicides occur well beyond midlife, especially so for men. Importantly, in the study of Gunnell and colleagues, 18 year old conscripts were followed up for 5-26 years, i.e., up to the ages of 23-44 years only. As a consequence, the majority of all suicides that will eventually be observed in this study cohort have not yet occurred. Changing patterns of suicide characteristics in later life could therefore easily level or even invert the reported negative association between intelligence and suicide. It may well be that, for the minority of male suicides that occur during early adulthood, low intelligence is to some extent predictive, conceivably mediated via the nexus of social, sexual, educational, or occupational non-achievement, crisis proneness, and early onset mental disorders like schizophrenia. However, this study’s short follow up frame cannot properly address and may even mask the actual association between intelligence and risk of suicide over lifetime. [1] Gunnell D, Magnusson PKE, Rasmussen F. Low intelligence test scores in 18 year old men and risk of suicide: cohort study. BMJ 2005;330:167-70. (22 January), doi:10.1136/bmj.38310.473565.8F (published 22 December 2004) [2] Morselli H. Suicide: an essay on comparative moral statistics. London: C Kegal Paul, 1881:247-8. [3] Lester D. Why people kill themselves: a 1990s summary of research findings on suicidal behavior. Springfield (Illinois): Charles C Thomas, 1992:392. [4] Voracek M. National intelligence and suicide rate: an ecological study of 85 countries. Pers Individ Dif 2004;37:543-53. [5] Voracek M. National intelligence, suicide rate in the elderly, and a threshold intelligence for suicidality: an ecological study of 48 Eurasian countries. J Biosoc Sci (in press). Competing interests: None declared |
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Dietmar Fuchs, Division of Biological Chemistry, Biocentre Innsbruck Medical University, 6020 Innsbruck, Austria, Katharina Schroecksnadel, Christiana Winkler
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With interest we read the article by Gunnell et al. on a strong relationship between intelligence test performance and subsequent risk of suicide in men (1): the authors observed that the risk of suicide was significantly higher in individuals with poorer test scores and they concluded that reduced cognitive ability may increase suicide risk when, e.g., going through an acute life crisis. Mood disturbances as well as cognitive impairment are likely linked to a disturbed metabolism of monoamine 5-hydroxytryptamine (serotonin) (2,3). The production of serotonin depends on the availability of its biosynthetic precursor, the essential amino acid tryptophan. During cellular immune response, Th1-type cytokine interferon-gamma stimulates tryptophan degradation by the enzyme indoleamine-(2,3)-dioxygenase in various cells including monocyte-derived macrophages and dendritic cells. Thereby, deprivation of tryptophan represents an important antimicrobial and antitumoural immune defence mechanism. It is very plausible that increased degradation of tryptophan during chronic inflammatory conditions will impair not only tryptophan metabolism but also serotonin production, and thus cognitive ability and risk for depression is increased in the same individual. On the one hand, several studies demonstrated a relationship between blood tryptophan concentrations and cognitive ability in patients with dementia (4), on the other hand also poor quality of life in cancer patients was found to be associated with immune activation and with lowered blood tryptophan concentrations (5). Both clinical conditions may share a common aetiology which could explain the association between depression and cognitive impairment, namely impaired serotonergic function. Genetically determined serotonin receptor affinity and distribution on cells will be important for basic intelligence, acquired cognitive impairment and depression may develop preferentially in individuals with subnormal affinity of serotonin receptors, and it may represent another consequence of immune activation which reduces blood tryptophan concentrations and causes shortage in serotonin availability. Katharina Schroecksnadel
Division of Biological Chemistry; Biocentre, Innsbruck Medical University, 6020 Innsbruck, Austria 1. Gunnell D, Magnusson PKE, Rasmussen F. Low intelligence test scores in 18 year old men and risk of suicide: cohort study. BMJ 2005;330(7484):167. Epub 2004 Dec 22. 2. Buhot MC, Martin S, Segu L. Role of serotonin in memory impairment. Ann Med 2000;32(3):210-21. 3. Widner B, Laich A, Sperner-Unterweger B, Ledochowski M, Fuchs D. Neopterin production, tryptophan degradation, and mental depression--what is the link? Brain Behav Immun 2002;16(5):590-5 4. Widner B, Leblhuber F, Walli J, Tilz GP, Demel U, Fuchs D. Tryptophan degradation and immune activation in Alzheimer's disease. J Neural Transmission 2000;107:343-53. 5. Huang A, Fuchs D, Widner B, Glover C, Henderson DC, Allen-Mersh TG. Serum tryptophan decrease correlates with immune activation and impaired quality of life in colorectal cancer. Brit J Cancer 2002;86:1691- 6. Competing interests: None declared |
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