Mediators of the Effect of Childhood Socioeconomic Status on Late Midlife Cognitive Abilities : A Four Decade Longitudinal Study

Peer reviewe

Associations between jet lag and cortisol diurnal rhythms after domestic travel.

Objective: Millions of adults in the United States travel abruptly across time zones each year. Nevertheless, the impact of traveling over relatively short distances (across 3 or fewer time zones) on diurnal patterning of typical physiological response patterns has yet to be studied in a large, epidemiological sample. Design: The current research focuses on 764 middle-aged men comparing variations in diurnal cortisol regulation based on number of time zones traveled eastward or westward the day before. Main Outcome Measure: Participants provided samples of salivary cortisol at waking, 30-min postwaking, 10 a.m., 3 p.m., and bedtime. Results: Eastward travel was associated with a steeper salivary cortiso

Pathophysiologic mechanisms, diagnosis, and management of dapsone-induced methemoglobinemia.

Dapsone is a leprostatic agent commonly prescribed for the treatment of patients with leprosy, malaria, and a variety of blistering skin diseases, including dermatitis herpetiformis. Methemoglobinemia, a potentially life-threatening condition in which the oxygen-carrying capacity of blood in body tissues is reduced, is a known adverse effect of dapsone use. The authors report a case of dapsone-induced methemoglobinemia observed in the emergency department during routine workup for contact dermatitis in a patient with celiac disease. The pathophysiologic mechanisms, diagnosis, and management of dapsone-induced methemoglobinemia are discussed

Power, Reverse Salient, Technological System, Technology Studies Theory and Practice in the Study of Technological Systems

This dissertation is intended to further technology studies by analyzing some of its important methodological tools and using those tools in combination to study complex technological systems in an historical context. The first chapter of the dissertation examines in detail four influential models by which complex technological systems have been analyzed: Hughes’s system model, Bijker’s social construction model, Latour, Callon, and Law’s actor-network model, and Ruth Schwartz Cowan’s consumption junction model. For each model, I summarize the seminal works, analyze the uses of the model in the literature, and offer some refinements to the models based on that analysis. Chapter 2 presents three case studies applying these models two different technological systems. First, the early development of the American automobile industry, 1895 to 1940, is studied using Hughes’s concepts of technological momentum and reverse salients. Second, the automobile’s impact on American society is explored over the same time period relying on Ruth Schwartz Cowan’s consumer-oriented perspective and Wiebe Bijker’s concept of technological frames. The third case study examines the technological means by which, over a long period of time, American cities were rendered impervious to huge conflagrations—commonplace until the end of the 19 t

Interactive effects of testosterone and cortisol on hippocampal volume and episodic memory in middle-aged men

Animal and human research suggests that testosterone is associated with hippocampal structure and function. Studies examining the association between testosterone and either hippocampal structure or hippocampal-mediated cognitive processes have overwhelmingly focused on the effects of testosterone alone, without considering the interaction of other neuroendocrine factors. The aim of the present study was to examine the interactive effects of testosterone and cortisol in relation to hippocampal volume and episodic memory in a sample of late-middle aged men from the Vietnam Era Twin Study of Aging. The average age of participants was 56.3 years (range 51-60). Salivary hormone samples were collected at multiple time-points on two non-consecutive at-home days, and an in-lab assessment. Area under the curve with respect to ground measures for cortisol and testosterone were utilized. Significant testosterone-by-cortisol interactions were observed for hippocampal volume, and episodic memory. When cortisol levels were elevated (1 SD above the mean), testosterone levels were positively associated with hippocampal volume and memory performance. However, when cortisol levels were low (1 SD below the mean), testosterone levels were inversely related to hippocampal volume and memory performance. These findings suggest that in context of high cortisol levels, testosterone may be neuroprotective. In contrast, low testosterone may also be neuroprotective in the context of low cortisol levels. To our knowledge this is the first demonstration of such an interaction in a structural brain measure and an associated cognitive ability. These results argue in favor of broadening neuroendocrine research to consider the simultaneous and interactive effects of multiple hormones on brain structure and function

Pupillary Responses as a Biomarker of Early Risk for Alzheimer’s Disease

Task-evoked pupillary responses may be a psychophysiological biomarker of early risk for mild cognitive impairment (MCI) and Alzheimer's disease (AD). Pupil dilation during cognitive tasks reflects cognitive effort until compensatory capacity is surpassed and performance declines are manifest, and reflects activation in the locus coeruleus, where degenerative changes have been found in the earliest stages of AD. We recorded pupillary responses during digit span recall in 918 participants ages 56-66. Despite normal performance, amnestic single-domain MCI (S-MCI) participants showed greater pupil dilation than non-amnestic S-MCI and cognitively normal (CN) participants at lower cognitive loads. Multi-domain MCI (M-MCI) participants failed to modulate effort across cognitive loads and showed poorer performance. Pupillary responses differentiated MCI and CN groups. Amnestic S-MCI participants required compensatory effort to maintain performance, consistent with increased risk for decline. Greater effort in CN individuals might indicate risk for MCI. Results are consistent with dysfunction in locus coeruleus-linked brain systems. This brief task shows promise as a biomarker for early MCI and AD risk prediction

Genetic and Environmental Influences on Cortisol Regulation Across Days and Contexts in Middle-Aged Men

Cortisol is an indicator of hypothalamic–pituitary–adrenal axis responsivity to stress, but few twin studies have examined the heritability of cortisol concentrations in adults across the diurnal cycle and in different contexts. Saliva samples were provided by 783 middle-aged male twins on one laboratory and two home days as part of the Vietnam Era Twin Study of Aging. Significant cortisol heritability estimates were found for laboratory measures only: awakening (.56); 30 min after awakening (.48); 1000 h (.42); mean output across the day (.43); and mean cortisol awakening response (.64). Twin correlations at home were low. In the laboratory, they were unchanged for fraternal twins, but increased for identical twins. Greater measurement error at home did not appear to account for home-laboratory differences. The results suggest that genetic factors influence cortisol responses to specific environmental stressors. Thus, cortisol levels are correlated in identical twins only when they undergo similar experiences