Review Mean Genes and the Biology of Aggression: A Critical Review of Recent Animal and Human Research

Abstract

Recent genetic work has suggested that abnormalities in serotonin biochemistry are directly causally linked to aggressive behavior, and there appears to be a consensus in the psychiatric literature that low levels of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid are specifically associated with impulsive violent behavior. We review the limitations of the genetic studies and conduct a meta-analysis of 39 studies linking 5-HIAA to aggression in humans. No differences in mean 5-HIAA levels were found between groups of violent impulsive psychiatric patients and groups of subjects diagnosed with other psychiatric or medical conditions not considered to involve violence once these levels had been corrected for three nonpsychiatric sources of variation (age, sex and height). However, mean 5-HIAA levels in both of these groups were lower than the mean corrected level in groups of normal healthy volunteers. The results confirm an association between low 5-HIAA levels and psychiatric disorders, but fail to support any specific relationship between low 5-HIAA levels and impulsive aggression or criminality. It is premature and misleading to speak of "mean genes" (Hen 1996) or a specific neurochemistry of aggressive behavior.

Bayesian Analysis of Genetic Associations of Skin Lesions and Behavioural Traits to Identify Genetic Components of Individual Aggressiveness in Pigs

“…Aggressive phenotypes are driven by multiple genes with pleiotropic effects on non-aggressive traits (Balaban et al 1996), and understanding the impacts of selection against aggression via LS on other behavioural traits is an important step before advocating selection. In a later publication, the genetic correlation between LS and nonsocial behavioural phenotypes will be described.…”

The Neuropsychopharmacology of Criminality and Aggression

“…One pos si ble rea son for these dis crep an cies is the greater se ver ity of ag gres sion in the ear lier study. In a metaanalysis of 5-HIAA stud ies of aggres sion, Balaban and oth ers found that, when cor rected for the con found ing fac tors of height, sex, and age, 5-HIAA was cor re lated with the pres ence of a treated psy chi at ric dis or der but not with par tic u lar be hav ioural in di ces (2). How ever, in its anal y sis the re view grouped sub jects in each study together and thus may not have been able to de tect im por tant dif fer ences.…”

“…The phre no log i cal con no ta tions of early case stud ies such as that of Phineas Gage, the ques tion able va lid ity of early psychosurgical stud ies, and ques tions about eth i cal re search con trib uted to early skep ti cism about the va lid ity of the as soci a tions made be tween brain ab nor mal i ties and ag gres sive be hav iour, as well as to an ap pre hen sion of the pos si ble so cial con se quences of hasty sci en tific con clu sions. Res er va tions con tinue: As stated in a re cent crit i cal re view, "Ten ta tive find ings cau tiously re ported in the tech ni cal lit er a ture are often over sim pli fied in the clin i cal sci en tific or lay me dia and in com mu ni ca tions with gov ern men tal pol icy-makers" (2). Con cerns like this have led to im por tant and ap pro pri ate changes in the way ex per i men tal stud ies have been car ried out in an i mal and hu man sub jects, as well as an in creased aware ness of the need to study ag gres sion and crim i nal ity in con text by in te grat ing bi o log i cal stud ies with other sci en tific dis ci plines.…”

Psychic Plasticity, Resilience, and Reactions to Media Violence

“…aggression in rats. Low serotonin levels, then, may be correlated specifically with impulsive, violent aggression (Krakowski, 2003) or more generally as an indicator of general psychopathology in which intermittent impulsive aggression occurs (Balaban, Alper, & Kasamon, 1996). Genetic predispositions to certain mental illness may also contribute to one's risk of violence.…”