MidCog study: a prospective, observational cohort study investigating health literacy, self-management skills and cognitive function in middle-aged adults.

INTRODUCTION: The lack of definitive means to prevent or treat cognitive impairment or dementia is driving intense efforts to identify causal mechanisms. Recent evidence suggests clinically meaningful declines in cognition might present as early as middle age. Studying cognitive changes in middle adulthood could elucidate modifiable factors affecting later cognitive and health outcomes, yet few cognitive ageing studies include this age group. The purpose of the MidCog study is to begin investigations of less-studied and potentially modifiable midlife determinants of later life cognitive outcomes. METHODS AND ANALYSIS: MidCog is a prospective cohort study of adults ages 35-64, with two in-person interviews 2.5 years apart. Data will be collected from interviews, electronic health records and pharmacy fill data. Measurements will include health literacy, self-management skills, cognitive function, lifestyle and health behaviours, healthcare use, health status and chronic disease outcomes. Associations of health literacy and self-management skills with health behaviours and cognitive/health outcomes will be examined in a series of regression models, and moderating effects of modifiable psychosocial factors.Finally, MidCog data will be linked to an ongoing, parallel cohort study of older adults recruited at ages 55-74 in 2008 ('LitCog'; ages 70-90 in 2023), to explore associations between age, health literacy, self-management skills, chronic diseases, health status and cognitive function among adults ages 35-90. ETHICS AND DISSEMINATION: The Institutional Review Board at Northwestern University has approved the MidCog study protocol (STU00214736). Results will be published in peer-reviewed journals and summaries will be provided to the funders of the study as well as patients.

Wireless, Battery-Free Implants for Electrochemical Catecholamine Sensing and Optogenetic Stimulation.

Neurotransmitters and neuromodulators mediate communication between neurons and other cell types; knowledge of release dynamics is critical to understanding their physiological role in normal and pathological brain function. Investigation into transient neurotransmitter dynamics has largely been hindered due to electrical and material requirements for electrochemical stimulation and recording. Current systems require complex electronics for biasing and amplification and rely on materials that offer limited sensor selectivity and sensitivity. These restrictions result in bulky, tethered, or battery-powered systems impacting behavior and that require constant care of subjects. To overcome these challenges, we demonstrate a fully implantable, wireless, and battery-free platform that enables optogenetic stimulation and electrochemical recording of catecholamine dynamics in real time. The device is nearly 1/10th the size of previously reported examples and includes a probe that relies on a multilayer electrode architecture featuring a microscale light emitting diode (µ-LED) and a carbon nanotube (CNT)-based sensor with sensitivities among the highest recorded in the literature (1264.1 nA µM-1 cm-2). High sensitivity of the probe combined with a center tapped antenna design enables the realization of miniaturized, low power circuits suitable for subdermal implantation even in small animal models such as mice. A series of in vitro and in vivo experiments highlight the sensitivity and selectivity of the platform and demonstrate its capabilities in freely moving, untethered subjects. Specifically, a demonstration of changes in dopamine concentration after optogenetic stimulation of the nucleus accumbens and real-time readout of dopamine levels after opioid and naloxone exposure in freely behaving subjects highlight the experimental paradigms enabled by the platform.

Soft, Skin-Interfaced Microfluidic Systems with Passive Galvanic Stopwatches for Precise Chronometric Sampling of Sweat.

Comprehensive analysis of sweat chemistry provides noninvasive health monitoring capabilities that complement established biophysical measurements such as heart rate, blood oxygenation, and body temperature. Recent developments in skin-integrated soft microfluidic systems address many challenges associated with standard technologies in sweat collection and analysis. However, recording of time-dependent variations in sweat composition requires bulky electronic systems and power sources, thereby constraining form factor, cost, and modes of use. Here, presented are unconventional design concepts, materials, and device operation principles that address this challenge. Flexible galvanic cells embedded within skin-interfaced microfluidics with passive valves serve as sweat-activated "stopwatches" that record temporal information associated with collection of discrete microliter volumes of sweat. The result allows for precise measurements of dynamic sweat composition fluctuations using in situ or ex situ analytical techniques. Integrated electronics based on near-field communication (NFC) protocols or docking stations equipped with standard electronic measurement tools provide means for extracting digital timing results from the stopwatches. Human subject studies of time-stamped sweat samples by in situ colorimetric methods and ex situ techniques based on inductively coupled plasma mass spectroscopy (ICP-MS) and chlorodimetry illustrate the ability to quantitatively capture time-dynamic sweat chemistry in scenarios compatible with field use.