Melatonin-dependent changes in neurosteroids are associated with increased aggression in a seasonally breeding rodent

Aggression is a complex social behaviour that allows individuals to compete for access to limited resources (eg, mates, food and territories). Excessive or inappropriate aggression, however, has become problematic in modern societies, and current treatments are largely ineffective. Although previous work in mammals suggests that aggressive behaviour varies seasonally, seasonality is largely overlooked when developing clinical treatments for inappropriate aggression. Here, we investigated how the hormone melatonin regulates seasonal changes in neurosteroid levels and aggressive behaviour in Siberian hamsters, a rodent model of seasonal aggression. Specifically, we housed males in long-day (LD) or short-day (SD) photoperiods, administered timed s.c. melatonin injections (which mimic a SD-like signal) or control injections, and measured aggression using a resident-intruder paradigm after 9 weeks of treatment. Moreover, we quantified five steroid hormones in circulation and in brain regions associated with aggressive behaviour (lateral septum, anterior hypothalamus, medial amygdala and periaqueductal gray) using liquid chromatography-tandem mass spectrometry. SD hamsters and LD hamsters administered timed melatonin injections (LD-M) displayed increased aggression and exhibited region-specific decreases in neural dehydroepiandrosterone, testosterone and oestradiol, but showed no changes in progesterone or cortisol. Male hamsters also showed distinct associations between neurosteroids and aggressive behaviour, in which neural progesterone and dehydroepiandrosterone were positively correlated with aggression in all treatment groups, whereas neural testosterone, oestradiol and cortisol were negatively correlated with aggression only in LD-M and SD hamsters. Collectively, these results provide insight into a novel neuroendocrine mechanism of mammalian aggression, in which melatonin reduces neurosteroid levels and elevates aggressive behaviour.

An evaluation of staff and patient views of and strategies employed to manage inpatient aggression and violence on one mental health unit: a pluralistic design

Following an initial springboard study, a further more extensive piece of research was conducted to identify and evaluate approaches used to manage patient aggression and violence on three acute mental health wards. Data were gathered using an incident form, a questionnaire and interviews. The views of patients (n = 80), nurses (n = 72) and medical staff (n = 10) were explored. Findings revealed a clear distinction between the way staff and patients view both the problem and the response. Patients' view present staff approaches as 'controlling' and believe that environmental and poor communication factors underpin aggressive behaviour. Staff, conversely, attribute aggressive behaviour to internal patient and external factors, which may explain the reason for approaches used. A strong correlation was found between type of patient aggression and response (r = 0.36, P < 0.000) and a high percentage of incidents reported were of an aggressive, as opposed to violent, nature. For example 70% of incidents involved verbal abuse or threat. Despite this, 47% (n = 103) of approaches incorporated the use of medication, restraint or seclusion. These are commonly referred to as traditional methods. Patients clearly view this controlling style as a part of the problem and an emphasis upon control and symptom reduction may be inappropriate given the type of aggression encountered. Key issues were further analysed using an internal, external and situational model, each of which endeavour to explain reasons for patient aggression from different perspectives. It is this emphasis upon sole perspectives that may both contribute to and result in the use of a limited number of management approaches adopted in practice. The integration of all three models to examine the complex nature of patient aggression and violence from a variety of perspectives may be the way forward. As a result, approaches to deal with this problem could be more meaningful and subsequently effective.