HPA-axis activity as a predictor of future disruptive behaviors in young adolescents

Low HPA-axis activity has been proposed as a risk factor for disruptive behaviors. However longitudinal data on this topic are practically lacking. In the present study we investigated if low HPA-axis activity predicted future disruptive behaviors. We included 1,399 boys and girls from the Dutch general population, initially aged 10-12 years. At the first assessment, basal cortisol levels were assessed. At the first assessment and at follow-up 2 years later disruptive behaviors were assessed with parent and self-report questionnaires. The results suggest that the association between low cortisol levels at 8.00 p.m. and future disruptive behaviors according to the parents was only present for boys. More importantly however, the results suggest that low HPA-axis activity is not a good predictor for disruptive behaviors, but could be valuable to identify those with a poor prognosis, once disruptive behaviors are present in preadolescence.     

Impact estimates of nosocomial bloodstream infection: looking from a different angle

Mortality associated with nosocomial bloodstream infection is multifactorial. Source of infection, etiology, age, underlying disease, acute illness, and appropriateness of antimicrobial therapy all contribute to the final outcome. As such, estimates of mortality attributable to bloodstream infection may differ largely according to the presence or absence of risk factors in distinct patient populations. The adverse effect of nosocomial bloodstream infection for the individual patient is substantial, with about a doubling of the risk of death. Yet, in settings with a high standard of care in terms of infection prevention and control, the occurrence rate of bloodstream infection is relatively low and therefore its impact on overall ICU mortality rather limited. As a consequence, untargeted interventional studies focused on infection prevention should use occurrence rate of infection rather than mortality as outcome variable.     

Age-related differences in pre-movement antagonist muscle co-activation and reaction-time performance

Multiple causes contribute to the prolonged reaction-times (RT) observed in elderly persons. The involvement of antagonist muscle co-activation remains unclear. Here the Mm. Biceps and Triceps Brachii activation in 64 apparently healthy elderly (80 ± 6 years) and 60 young (26 ± 3 years) subjects were studied during a simple RT-test (moving a finger using standardized elbow-extension from one pushbutton to another following a visual stimulus). RT was divided in pre-movement-time (PMT, time for stimulus processing) and movement-time (MT, time for motor response completion). RT-performance was significantly worse in elderly compared to young; the slowing was more pronounced for MT than PMT (respectively 101 ± 10 ms and 41 ± 6 ms slower, p < 0.01). Elderly subjects showed significantly higher (p < 0.01) antagonist muscle co-activation during the PMT-phase, which was significantly related to worse MT and RT (p < 0.01). During the MT-phase, antagonist muscle co-activation was similar for both groups. It can be concluded that increased antagonist muscle co-activation in elderly persons occurs in an early phase, already before the start of the movement. These findings provide further understanding of the underlying mechanisms of age-related slowing of human motor performance.     

Persistence of anxiety disorders and concomitant changes in cortisol

In a clinical sample of 116 children and adolescents we studied the relation between the course of an anxiety disorder during treatment and the concomitant changes in cortisol levels. Assessments at baseline, after three months, and at one-year follow-up were performed with the Anxiety Disorders Interview Schedule. When we compared cortisol levels at baseline and one-year follow-up, persistence of the anxiety disorder was associated with both increased daytime cortisol production (F=3.2, p=0.04) and a trend towards a decreased cortisol morning rise (F=2.4, p=0.09). At one-year follow-up daytime cortisol production was lowest in the early remitters (109.7±29.2 h mmol/l), higher in the late remitters (121.0±40.0 h mmol/l) and highest in the non-remitters (131.1±48.9 h mmol/l). Early remitters had the highest cortisol morning rise (1.1±1.5 h mmol/l), followed by the late remitters (0.8±1.8 h mmol/l), the non-remitters had the lowest cortisol morning rise (0.07±1.7 h mmol/l). Persistence of an anxiety disorder may thus lead to changes in HPA-axis functioning, underscoring the importance adequate treatment of anxiety disorders.     

Childhood problem behavior and parental divorce: evidence for gene–environment interaction

Objective

The importance of genetic and environmental influences on children’s behavioral and emotional problems may vary as a function of environmental exposure. We previously reported that 12-year-olds with divorced parents showed more internalizing and externalizing problems than children with married parents, and that externalizing problems in girls precede and predict later parental divorce. The aim of the current study was to investigate as to whether genetic and environmental influences on internalizing and externalizing problems were different for children from divorced versus non-divorced families.

Methods

Maternal ratings on internalizing and externalizing problems were collected with the Child Behavior Checklist in 4,592 twin pairs at ages 3 and 12?years, of whom 367 pairs had experienced a parental divorce between these ages. Variance in internalizing and externalizing problems at ages 3 and 12 was analyzed with biometric models in which additive genetic and environmental effects were allowed to depend on parental divorce and sex. A difference in the contribution of genetic and environmental influences between divorced and non-divorced groups would constitute evidence for gene–environment interaction.

Results

For both pre- and post-divorce internalizing and externalizing problems, the total variances were larger for children from divorced families, which was mainly due to higher environmental variances. As a consequence, heritabilities were lower for children from divorced families, and the relative contributions of environmental influences were higher.

Conclusions

Environmental influences become more important in explaining variation in children’s problem behaviors in the context of parental divorce.