Do Current Measures of Polygenic Risk for Mental Disorders Contribute to Population Variance in Mental Health?

The polygenic risk score (PRS) allows for quantification of the relative contributions of genes and environment in population-based studies of mental health. We analyzed the impact of transdiagnostic schizophrenia PRS and measures of familial and environmental risk on the level of and change in general mental health (Short-Form-36 mental health) in the Netherlands Mental Health Survey and Incidence Study-2 general population sample, interviewed 4 times over a period of 9 years, yielding 8901 observations in 2380 individuals. Schizophrenia PRS, family history, somatic pain, and a range of environmental risks and social circumstances were included in the regression model of level of and change in mental health. We calculated the relative contribution of each (group of) risk factor(s) to the variance in (change in) mental health. In the combined model, familial and environmental factors explained around 17% of the variance in mental health, of which around 5% was explained by age and sex, 30% by social circumstances, 16% by pain, 22% by environmental risk factors, 24% by family history, and 3% by PRS for schizophrenia (PRS-SZ). Results were similar, but attenuated, for the model of mental health change over time. Childhood trauma and gap between actual and desired social status explained most of the variance. PRS for bipolar disorder, cross-disorder, and depression explained less variance in mental health than PRS-SZ. Polygenic risk for mental suffering, derived from significance-testing in massive samples, lacks impact in analyses focusing on prediction in a general population epidemiological setting. Social-environmental circumstances, particularly childhood trauma and perceived status gap, drive most of the attributable variation in population mental health.     

High‐risk human papillomavirus DNA load in a population‐based cervical screening cohort in relation to the detection of high‐grade cervical intraepithelial neoplasia and cervical cancer

In a population‐based cervical screening cohort, we determined the value of type‐specific viral load assessment for the detection of high‐grade cervical intraepithelial neoplasia and cervical cancer (≥CIN2). Viral load was determined by type‐specific real‐time PCR in women with single HPV16,‐18,‐31 and ‐33 infections, as determined by GP5+/6+‐PCR. Study endpoints were the detection of cumulative ≥CIN2 or ≥CIN3 within 18 months of follow‐up. High viral loads of HPV16,‐31, and ‐33 were predictive for ≥CIN2 (relative risk of 1.6 (95% CI: 1.3–1.9), 1.7 (95% CI: 1.1–2.7) and 1.9 (95% CI: 1.1–3.1) per 10‐fold change in viral load, respectively). For HPV18, the relative risk was of similar magnitude (1.5, 95% CI: 0.7–3.1), though not significant (p = 0.3). Subsequently, we determined the sensitivities of viral load for ≥CIN2 and ≥CIN3 in HPV DNA‐positive women using viral load thresholds previously defined in a cross‐sectional study. These thresholds were based on the 25th, 33rd and 50th percentiles of type‐specific HPV16,‐18,‐31 or ‐33 viral load values found in women with normal cytology. For all types, combined sensitivities for ≥CIN2 were 93.5%, 88.8% and 77.7% for the 25th, 33rd and 50th percentile thresholds, respectively. Response‐operator‐characteristics (ROC) curve analysis showed that viral load testing on HPV DNA‐positive women in addition to or instead of cytology may result in an increased sensitivity for ≥CIN2, but at the cost of a marked decrease in specificity in relation to cytology. Similar results were obtained when using ≥CIN3 as endpoint. In conclusion, in a cervical screening setting viral load assessment of HPV16, 18, 31 and 33 has no additive value to stratify high‐risk HPV GP5+/6+‐PCR‐positive women for risk of ≥CIN2 or ≥CIN3. © 2008 Wiley‐Liss, Inc.     

The temporal order of fluctuations in atopic disease symptoms and attention-deficit/hyperactivity disorder symptoms: a time-series study in ADHD patients

European Child & Adolescent Psychiatry - In a recent meta-analysis, we found that atopic diseases, like asthma and allergic rhinitis, occur more frequently prior to the onset of...     

Solution space: Monitoring the dynamics of motor rehabilitation

This article presents and discusses a perspective on the concept of “solution space” in physiotherapy. The model is illustrated with a subjective assessment of the way movements are performed and an objective quantification of the dynamics of the recovery process for a patient with a knee injury. Based on insights from the domain of human motor control, solution space is a key concept in our recovery model that explains the emergence of a variety of adaptive changes that may occur in the movement system recovering from an injury. The three dimensions that span the solution space are: (1) information and control processes; (2) time; and (3) degrees of freedom. Each dimension is discussed within the context of feasible physiotherapeutic assessments to identify and facilitate desirable behavioral patterns or bypass emerging but undesirable behavioral patterns that could impede both short- and long-term recovery. Central to this article is our view on the relationship between the recovery process and the three dimensions of the solution space, which determines the model’s usefulness as a motor-rehabilitation monitoring tool.     

Amphetamine effects on startle gating in normal women and female rats

Background  Dopamine agonists disrupt prepulse inhibition (PPI) of startle in male rodents. In humans, this is observed only in some studies. We reported that PPI was disrupted by d-amphetamine in men, but only among those with high basal PPI levels. Here, amphetamine effects on PPI were tested in normal women and female rats. Materials and methods  Acoustic startle and PPI were tested in normal women after placebo or 20 mg amphetamine, in a double-blind, crossover design, and in female rats after vehicle or 4.5 mg/kg amphetamine. Rats were from Sprague–Dawley (SD) and Long Evans (LE) strains that differ significantly in gene expression in PPI-regulatory circuitry, including levels of nucleus accumbens (NAC) catechol-O-methyl transferase (COMT) mRNA. Results  Amphetamine was bioactive in humans based on quantitative autonomic and self-rating measures, but did not significantly change startle magnitude or PPI across all subjects. Amphetamine’s effects on PPI in women correlated significantly (p < 0.0008) with placebo PPI levels (reducing PPI only in women whose basal PPI levels exceeded the sample median) and with measures of novelty and sensation seeking. Amphetamine decreased PPI in SD rats that have relatively low NAC COMT gene expression and increased PPI in LE rats that have relatively high NAC COMT gene expression. Conclusion  The dopaminergic regulation of PPI in humans is related to basal levels of sensorimotor gating and to specific personality traits in normal men and women. In rats, the effects of amphetamine on PPI differ significantly in strains with low vs. high NAC COMT expression.     

P-glycoprotein limits oral availability, brain penetration, and toxicity of an anionic drug, the antibiotic salinomycin

Salinomycin is a polyether organic anion that is extensively used as a coccidiostatic antibiotic in poultry and commonly fed to ruminant animals to improve feed efficiency. However, salinomycin also causes severe toxicity when accidentally fed to animals in high doses. In addition, humans are highly sensitive to salinomycin and severe toxicity has been reported. Multidrug efflux transporters like P-glycoprotein (P-gp), BCRP, and MRP2 are highly expressed in the intestine and can restrict the oral uptake and tissue penetration of xenobiotics. The purpose of this study was to investigate whether the anionic drug salinomycin is a substrate for one or more of these efflux pumps. Salinomycin was actively transported by human MDR1 P-gp expressed in polarized MDCK-II monolayers but not by the known organic anion transporters human MRP2 and murine Bcrp1. Using P-gp-deficient mice, we found a marked increase in plasma salinomycin concentrations after oral administration and decreased plasma clearance after intravenous administration. Furthermore, absence of P-gp resulted in significantly increased brain penetration. P-gp-deficient mice also displayed clearly increased susceptibility to salinomycin toxicity. Thus far, P-gp was thought to affect mainly hydrophobic, positively charged or neutral drugs in vivo. Our data show that P-gp can also be a major determinant of the pharmacokinetic behavior and toxicity of an organic anionic drug. Variation in P-gp activity might thus directly affect the effective exposure to salinomycin and possibly to other anionic drugs and toxin substrates. Individuals with reduced or absent P-gp activity could therefore be more susceptible to salinomycin toxicity.     

The Structure of The Extended Psychosis Phenotype in Early Adolescence—A Cross-sample Replication

The extended psychosis phenotype, or the expression of nonclinical positive psychotic experiences, is already prevalent in adolescence and has a dose-response risk relationship with later psychotic disorder. In 2 large adolescent general population samples (n = 5422 and n = 2230), prevalence and structure of the extended psychosis phenotype was investigated. Positive psychotic experiences, broadly defined, were reported by the majority of adolescents. Exploratory analysis with Structural Equation Modelling (Exploratory Factor Analysis followed by Confirmatory Factor Analysis [CFA]) in sample 1 suggested that psychotic experiences were best represented by 5 underlying dimensions; CFA in sample 2 provided a replication of this model. Dimensions were labeled Hallucinations, Delusions, Paranoia, Grandiosity, and Paranormal beliefs. Prevalences differed strongly, Hallucinations having the lowest and Paranoia having the highest rates. Girls reported more experiences on all dimensions, except Grandiosity, and from age 12 to 16 years rates increased. Hallucinations, Delusions, and Paranoia, but not Grandiosity and Paranormal beliefs, were associated with distress and general measures of psychopathology. Thus, only some of the dimensions of the extended psychosis phenotype in young people may represent a continuum with more severe psychopathology and predict later psychiatric disorder.     

Anatomical substrates of cooperative joint-action in a continuous motor task: virtual lifting and balancing

An emerging branch of social cognitive neuroscience attempts to unravel the critical cognitive mechanisms that enable humans to engage in joint action. In the current experiment, differences in brain activity in participants engaging in solitary action and joint action were identified using whole brain fMRI while participants performed a virtual bar-balancing task either alone (S), or with the help of a partner in each of two separate joint-action conditions (isomorphic [Ji] and non-isomorphic [Jn]). Compared to the performing the task alone, BOLD signal was found to be stronger in both joint-action conditions at specific sites in the human mirror system (MNS). This activation pattern may reflect the demand on participants to simulate the actions of others, integrate their own actions with those of their partners, and compute appropriate responses. Increasing inter-dependence (complementarity) of movements being generated by cooperating individuals (Jn>Ji>S) was found to correlate with BOLD signal in the right anterior node of the MNS (pars opercularis), and the area around the right temporoparietal junction (TPJ). These data are relevant to current debates concerning the role of right IFG in complementary action, as well as evolving theories of joint action.