Information Channels and Biomarkers of Disease

Current research in molecular epidemiology uses biomarkers to model the different disease phases from environmental exposure, to early clinical changes, to development of disease. The hope is to get a better understanding of the causal impact of a number of pollutants and chemicals on several diseases, including cancer and allergies. In a recent paper Russo and Williamson (Med Stud, 2012) address the question of what evidential elements enter the conceptualisation and modelling stages of this type of biomarkers research. Recent research in causality has examined Ned Hall’s distinction between two concepts of causality: production and dependence (Hall in Causation and counterfactuals. MIT Press, Cambridge, pp 225–276, 2004). In another recent paper, Illari (Philos Technol, p 20, 2011b) examined the relatively under-explored production approach to causality, arguing that at least one job of an account of causal production is to illuminate our inferential practices concerning causal linking. Illari argued that an informational account solves existing problems with traditional accounts. This paper follows up this previous work by investigating the nature of the causal links established in biomarkers research. We argue that traditional accounts of productive causality are unable to provide a sensible account of the nature of the causal link in biomarkers research, while an informational account is very promising.     

Stress and support as related to postpartum paternal mental health and perceptions of the infant

This study examined the relationship of stress and social support to psychological adjustment, attitudes towards the parental role, and perceptions of infant behavior in two groups of fathers: an index group of 50 men whose wives had a diagnosed postpartum depression, and a control group of 50 men whose wives had no such disorder. Fathers with more stress and less support had higher levels of psychological symptomatology. Index fathers reported more stress, particularly from work and economic pressures. Index fathers were also less likely than controls to report support from in-laws, other relatives, and friends. Stress, but not support, was associated with more negative perceptions of the marriage, the parental role, and infant behavior. Work-related stress was most likely to have an impact on paternal attitudes. These findings suggest the need to adopt a family focus when studying postpartum depression. © 1997 Michigan Association for Infant Mental Healt     

Brain responses to lexical-semantic priming in children at-risk for dyslexia

Deviances in early event-related potential (ERP) components reflecting auditory and phonological processing are well-documented in children at familial risk for dyslexia. However, little is known about brain responses which index processing in other linguistic domains such as lexicon, semantics and syntax in this group. The present study investigated effects of lexical-semantic priming in 20- and 24-month-olds at-risk for dyslexia and typically developing controls in two ERP experiments. In both experiments an early component assumed to reflect facilitated lexical processing for primed words was enhanced in the at-risk group compared to the control group. Moreover, an N400-like response which was prominent in the control group was attenuated or absent in at-risk children. Results suggest that deficiencies in young children at-risk for dyslexia are not restricted to perceptual and lower-level phonological abilities, but also affect higher order linguistic skills such as lexical and semantic processing.     

“But Others Do It!”: Do Misperceptions of Schoolmate Alcohol and Marijuana Use Predict Subsequent Drug Use Among Young Adolescents?

We examined the effects of perceived prevalence of drug use among same-age peers on adolescents' subsequent drug use. In 7^th grade, participants estimated prevalence of alcohol and marijuana use among 7^th-grade students in their school, reported own use of these drugs, receipt of offers to use these drugs, and frequency of contact with peers who use these drugs. In 8^th grade, participants reported their frequency of alcohol and marijuana use. Although perceived prevalence of drug use predicted subsequent alcohol and marijuana use when controlling for actual prevalence, these effects disappeared once participants' prior levels of drug use and proximal peer contacts were considered. Implications of findings for intervention programs aiming solely to increase accuracy of perceived prevalence estimates are discussed.     

Rank and reproduction among female langur monkeys: Aging and improvement (They're not just getting older,they're getting better)

An investigation of the social rank, reproduction, and ages of adult female Indian gray langur monkeys (Presbytis entellus) living in two colony social groups revealed that rank based on displacements is neither correlated with nor best predicted by female age or reproductive value. The hierarchy of female ranks is best conceptualized as a layered ranking system in which there are clusters of females of the same dominance rank forming layers within the structure. Statistical significance in frequencies of displacement differs between but not within these layered groups of females. Factors such as group composition, presence of uterine kin, reproductive state, and individual personality are hypothesized to predict changes in female rank far better than does reproductive value. Our data show that reproductive success increases with age. The infant survival record for the six oldest females in our colony was much better than for the five youngest adult females.     

Marijuana use from adolescence to young adulthood: multiple developmental trajectories and their associated outcomes.

This study used latent growth mixture modeling to identify discrete developmental patterns of marijuana use from early adolescence (age 13) to young adulthood (age 23) among a sample of 5,833 individuals. After the a priori removal of abstainers, 4 trajectory groups were identified: early high users, who decreased from a relatively high level of use at age 13 to a more moderate level: stable light users, who maintained a low level of use: steady increasers, who consistently increased use; and occasional light users, who began use at age 14 and used at low levels thereafter. Analyses of covariance comparing the trajectory groups on behavioral, socioeconomic, and health outcomes at age 29 revealed that abstainers consistently had the most favorable outcomes, whereas early high users consistently had the least favorable outcomes.