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IS-5.
HORMONES AND AGGRESSION
Organizer: Brain, Paul F.
School of Biological Sciences, University of Wales Swansea, Swansea, U.K
Symposium
Abstract
There
has been much progress since the early ‘primitive’ view that hormones
(notably testosterone) ‘cause’ aggression. The papers in this session
illustrate some recently revealed complexities in linking physiology and
behavior in infrahuman animals and our own species. Sanchez-Martin et al provide
tentative evidence that salivary testosterone levels in pre-school (especially
boys) may prove a ‘marker’ of conflict behavior. O’Connor et al in a study
involving giving testosterone to eugonadal males with partners found no evidence
to support the view that supraphysiological levels of the hormone augmented
aggression (reported by the patient or the partner). Salvador et al opine that
sports competitions are likely to provide socially acceptable situations for
studying the links between hormones and behavior in our own species. They also
provide tentative support for positive correlations between some measures of
offensive behavior in judo contests and testosterone. Haller et al work with
rats and suggest that plasma corticosterone levels influence hostile responding
in this (and other?) species. They suggest that ultradian variations in this
hormone account for changes in expressed behavior.
Sánchez-Martín, J.R., Fano, E.
, Cardas, J., Ahedo, L. ,
Brain* P.F. and Azpíroz, A.
Area
of Psychobiology, Faculty of Psychology, University of the Basque Country, San
Sebastian, Spain. *School of Biological Sciences, University of Wales Swansea,
Swansea, U.K.
A
study was performed to assess relationships between a series of behavioral
measures seen in the interactions of preschool children with their peers
(particularly aggressive behavior) and salivary testosterone levels. The
subjects were 28 boys and 20 girls of preschool age (4-5 years) videotaped in
San Sebastian in free play interactions. Their behavior was subsequently
ethologically evaluated, concentrating on levels of isolation, play and social
interactions (including giving and receiving aggression and affiliation).
Testosterone levels were measured twice using radioimmunoassay but the titers
were highly correlated. Significant positive correlations with testosterone on
the pooled data (boys and girls) were found for ‘proximity without
interaction’; ‘parallel activity’ and receiving aggression in ‘social
interactions’. A negative correlation was found between the hormone and
‘play’. When analyzing the data for boys and girls separately, a significant
direct correlation was found between testosterone and incidences of aggressive
behavior in ‘social interactions’ in boys. This gender also showed inverse
relationships between the hormone and ‘play’ and ‘proximity without
interaction’. Although the levels of hormone in boys and girls did not differ
at this age (most of their androgens are of adrenocortical origin), the girls
showed no such relationships. It could be the case, however, that the sexes
express their conflict behavior in different ways even at this early age.
Testosterone can be a useful biological marker for aggression (and behavioral
patterns reflecting different levels of sociability) in children (especially
boys). Much more work is needed, however, to evaluate the complex relationships
between early hormone titer and current and subsequent behavior.
IS-5.2.-EFFECTS
OF EXOGENOUS TESTOSTERONE ON SELF REPORTED AND PARTNER REPORTED AGGRESSION IN
MEN
O’Connor, D.B., Archer*, J., Hair**
, W.M. and Wu, F.C.W
Department of Endocrinology, Manchester Royal Infirmary, University of
Manchester, Manchester, UK. *Department of Psychology, University of
Central Lancashire, Preston, Lancashire, UK. **MRC Centre for Reproductive
Biology, Edinburgh, UK.
In nonhuman primates, aggressive behavior correlates directly with
testosterone (T) levels. In men, self-reported aggression does not reliably
correlate with circulating T levels. This study set out to investigate the
behavioral effects of supraphysiological levels of testosterone on self reported
and partner reported aggression. Thirty healthy eugonadal men with partners
(mean age = 28.2 years; range 19 – 45 years) and 7 hypogonadal men (mean age =
31.43 years; range 23 – 40 years) participated in this single-blind, placebo
controlled study. Participants were randomised into two treatment groups (n =
15) to receive: 1) 200 mg testosterone (T) enanthate, intramuscularly, weekly
for 8 weeks to raise T levels into the supraphysiological range; the active
group or 2) 200 mg sodium chloride, intramuscularly, weekly for 8 weeks; the
placebo group. The hypogonadal group received 200 mg T enanthate,
intramuscularly, bi-weekly for 8 weeks. All groups completed a battery of
behavior measures [Aggressive Provocation Questionnaire (O’Connor et
al, in press); Aggression Questionnaire (Buss & Perry, 1992); Aggression
Questionnaire-Partner version (O’Connor et
al., in press); Rathus Assertiveness Schedule (Rathus, 1973); State Self
Esteem Questionnaire (Heatherton & Polivy, 1991); Irritability sub-scale
(Buss & Burkee, 1957); Barratt Impulsivity Scale-11 (Barratt & Patton,
1983)] and a blood sample was obtained at baseline, week 4 and week 8.
Preliminary analysis has found no statistically significant increases in self
reported or partner reported aggression levels in any of the groups, although
there was a trend towards increased frequency of aggressive responding to
provoking scenarios at week 4 in the active group. No significant changes in
assertiveness or self esteem have been found. Surprisingly, the hypogonadal
group reported significantly higher levels of hostility at all time points
compared to the active and placebo groups. Plasma T levels were generally not
significantly correlated with any of the behaviour measures. Cognitive and motor
impulsivity emerged from stepwise multiple regression analysis as the most
important predictors of self-reported aggression, explaining significant
proportions of variance at different time points. These results generally do not
offer support to the hypothesis that supraphysiological levels of T lead to
increased self and partner reported aggression.
IS-5.3.-TESTOSTERONE
AND BEHAVIOR IN JUDO COMBAT
Salvador,
A., Suay, A.F., Martinez-Sanchis,
S., Simon, V.M. and Brain*, P.F.
Area of Psychobiology, Faculty of Psychololgy, University of Valencia,
Valencia, Spain.
*School of Biological Sciences, University of Wales Swansea, Swansea, UK
The
role of testosterone in competitive aggression is still open to debate in
humans. An important problem is the difficulty of finding adequate behavioral
measures. In fact, it has been repeatedly claimed that a main challenge for this
topic of research is identifying social situations which permit the study of the
role of testosterone in overt behavior comparable to investigation carried out
in other species. Sports competitions present several important opportunities to
analyse behavior associated with high competitiveness. In particular, contact
sports have an especialpropensity to
develop into aggressive behavior. With this in mind, the relationships between
testosterone levels measured before and after a judo combat and the behaviour
displayed during the combat itself were examined. An observational scale was
designed from activities usually shown by fighters in judo contests. This scale
grouped a number of different elements toform seven behavioural categories that
covered the entire period studied. These were threat, fighting, domination,
attack/counterattack, defense, observation and stop. Positive correlations were
found between offensive behaviours displayed in this kind of competition and
testosterone. Furthermore, this relationship supports previous data indicating
an association of testosterone with involvement and anger displayed during judo
contests as assessed by the coaches. Sports competitions appear to be socially
accepted situations that may be used to obtain information about
behavior/hormone relationships in our own species.
IS-5.4-PULSATING
CORTICOSTERONE SECRETION IN MALE RATS: FAST EFFECTS ON AGGRESSIVENESS
Haller,
J., Fabich, K. and Kruk*, M.R.
Institute
of Experimental Medicine, Budapest, Hungary. *Medical University,
Leiden, The Netherlands
Ultradian
fluctuations in plasma corticosterone have been demonstrated in monkeys and
humans. It has been recently shown that corticosterone secretion pulsates in
female rats and an attempt was made to assess whether levels also fluctuate in
male rats. The amplitude of oscillations was similar with that reported for
females but the period was larger in males (a phenomenon perhaps related to the
shorter corticosterone half-life in females). Male rats were studied in
aggressive encounters lasting only 5 min to reduce interference from
fight-induced stress reactions. Male rats were significantly more aggressive in
the increasing phase of their corticosterone fluctuation when confronting a male
intruder than counterparts in the decreasing phase of their corticosterone
fluctuations facing such opponents. Corticosterone fluctuations were
artificially mimicked by a combination of treatments with the corticosterone
synthesis inhibitor metyrapone and corticosterone. Again, males with increasing
plasma corticosterone levels were more aggressive than counterparts with a
decreasing plasma corticosterone concentration. It appears that ultradian
fluctuations in corticosterone affect the propensity of an animal to behave
aggressively. This suggests that the behavioural response to an aggressive
challenge may vary in the same animal across the day due to the pulsating nature
of corticosterone secretion.