Background. Studies examining the associations between psychiatric disorders, violence, suicidality and lowering cholesterol levels bring contradictive results. A biological mechanism for this relation is offered by the Engelberg’s theory. The aim of our study is to review all biological studies, trying to test this hypothesis. Methods and Results. The Engelberg’s theory was cited in 207 articles indexed in the Web of Science – 31.7 2005. Five other articles, not citing the theory but closely related to this topic were also included into the review. Only 20 biological studies examining the hypothesis were found, and only 7 of them supported it. Further we demonstrate that because of selection bias, association studies cannot be used to test this hypothesis. Interestingly from 43 associative studies published in psychiatric journals, 77 % findings supported the Engelberg theory while studies demonstrating the opposite results are published mostly in journals targeted to internal medicine- from 11 papers 82 % publicatitions did not supported the theory. Conclusions. Though the evidenced based knowledge is wildly accessible, outdated hypothesis is used to explain controversial results.

        Key words: cholesterol, serotonin, depression, suicidality, violence.