BMJ  2003;327:1168 (15 November), doi:10.1136/bmj.327.7424.1168-a

Letter

Risk of suicide in twins

Intelligence of twins and singletons may explain risk

The first 150 words of the full text of this article appear below.

EDITOR—Tomassini et al presented evidence for a lower suicide rate of twins compared with singletons.1 However, they did not present any data supporting their preferred explanative factor ("strong family ties") for this finding, and their explanation is therefore speculative. Other causal factors need to be considered. I give one example.

According to de Catanzaro's evolutionary theory of human suicide, a threshold intelligence is necessary for suicidality.2 A corollary of this hypothesis is that human intelligence and suicide mortality should be positively related.

This prediction has been confirmed in an ecological study of 85 countries.3 National intelligence is significantly positively related to the national suicide rate, and ethnic differences in intelligence correspond to ethnic differences in suicide rates. Furthermore, excess suicide prevalence has been observed in the highly gifted.3

Following these convergent strands of evidence it would be expected that population subgroups with a lower intelligence level than the . . . [Full text of this article]

Martin Voracek, research resident

Department of Psychoanalysis and Psychotherapy, Statistics and Documentation Branch, University of Vienna Medical School, A-1090 Vienna, Austria martin.voracek@akh-wien.ac.at


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Relevant Article

Risk of suicide in twins: 51 year follow up study
Cecilia Tomassini, Knud Juel, Niels V Holm, Axel Skytthe, and Kaare Christensen
BMJ 2003 327: 373-374. [Extract] [Full Text] [PDF]

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