Sub-second and multi-second dopamine dynamics underlie variability in human time perception.

Timing behaviour and the perception of time are fundamental to cognitive and emotional processes in humans. In non-human model organisms, the neuromodulator dopamine has been associated with variations in timing behaviour, but the connection between variations in dopamine levels and the human experience of time has not been directly assessed. Here, we report how dopamine levels in human striatum, measured with sub-second temporal resolution during awake deep brain stimulation surgery, relate to participants' perceptual judgements of time intervals.

Sub-second Dopamine Signals during Risky Decision-Making in Patients with Impulse Control Disorder.

Background: Impulse Control Disorder (ICD) in Parkinson's disease is a behavioral addiction arising secondary to dopaminergic therapies, most often dopamine receptor agonists. Prior research implicates changes in striatal function and heightened dopaminergic activity in the dorsal striatum of patients with ICD. However, this prior work does not possess the temporal resolution required to investigate dopaminergic signaling during real-time progression through various stages of decision-making involving anticipation and feedback.

Patterns of tau pathology identified with F-MK-6240 PET imaging.

Introduction: Positron emission tomography (PET) imaging for neurofibrillary tau allows investigation of the in vivo spatiotemporal progression of Alzheimer's disease (AD) pathology. We evaluated the suitability of F-MK-6240 in a clinical sample and determined the relationships among F-MK-6240 binding, age, cognition, and cerebrospinal fluid (CSF)-based AD biomarkers.

Methods: Participants (n = 101, 72 ± 9 years, 52% women) underwent amyloid PET, tau PET, structural T1-weighted magnetic resonance imaging, and neuropsychological evaluation.

Right parahippocampal volume deficit in an older population with posttraumatic stress disorder.

Background: Posttraumatic Stress Disorder (PTSD) is an increasingly prevalent condition among older adults and may escalate further as the general population including veterans from recent conflicts grow older. Despite growing evidence of higher medical comorbidity, cognitive impairment and dementia, and disability in older individuals with PTSD, there are very few studies examining brain cortical structure in this population. Hence, we examined cortical volumes in a cross-sectional study of veterans and civilians aged ≥50 years, of both sexes and exposed to trauma (interpersonal, combat, non-interpersonal).

Education differentially contributes to cognitive reserve across racial/ethnic groups.

Introduction: We examined whether educational attainment differentially contributes to cognitive reserve (CR) across race/ethnicity.

Methods: A total of 1553 non-Hispanic Whites (Whites), non-Hispanic Blacks (Blacks), and Hispanics in the Washington Heights-Inwood Columbia Aging Project (WHICAP) completed structural magnetic resonance imaging. Mixture growth curve modeling was used to examine whether the effect of brain integrity indicators (hippocampal volume, cortical thickness, and white matter hyperintensity [WMH] volumes) on memory and language trajectories was modified by education across racial/ethnic groups.

Parental History of Dementia Is Associated with Increased Small Vessel Cerebrovascular Disease.

Background: Small vessel cerebrovascular dysfunction that manifests on magnetic resonance imaging (MRI) as white matter hyperintensities (WMH) is linked to increased risk and progression of Alzheimer's disease (AD), but there is considerable debate about whether it represents a core feature of the disease. Parental history of dementia is a risk factor for AD, suggesting a strong heritable component; the examination of the extent to which parental history of dementia is associated with cerebrovascular disease could provide insight into the aggregation of AD and cerebrovascular disease.

Methods: This study included 481 community-dwelling older adults (mean age = 74.

Frailty and Its Correlates in Adults With Late Life Depression.

Objective: To investigate the rates of frailty and frailty characteristics and examine the clinical and neuropsychological correlates of frailty in adults with late life depression (LLD).

Methods: Data were used from the evaluation of 134 individuals over the age of 60 years (45 men, 89 women) with a depressive diagnosis who enrolled in studies for the treatment of their depression. Depression, neuropsychological functioning, white matter hyperintensity (WMH) burden via magnetic resonance imaging, and characteristics of frailty were assessed.

Magnetic Resonance Imaging Volumetry of Primary Nasopharyngeal Cancer in Patients Treated with Induction Gemcitabine and Cisplatin Followed by Concurrent Cisplatin and Volumetric Modulated Arc Therapy.

Introduction The addition of induction chemotherapy (IC) to the standard concurrent chemoradiotherapy (CCRT) is under consideration in locally advanced nasopharyngeal carcinoma (LANPC). To-date, no studies have reported primary gross tumour volume (GTVp) changes using gemcitabine and cisplatin as the IC phase in LANPC. We investigated the timing and magnitude of GTVp response throughout sequential gemcitabine and cisplatin IC and CCRT for LANPC.

Impact of Neoadjuvant Chemotherapy on the Administration of Concurrent Chemoradiation for Locally Advanced Nasopharyngeal Carcinoma.

Objectives The standard of care for locally advanced nasopharyngeal carcinoma (NPC) is concurrent cisplatin chemoradiotherapy. Neoadjuvant chemotherapy can be administered to downsize tumors before concurrent treatment to optimize radiation volumes. Our hypothesis was that the use of cisplatin in the neoadjuvant phase could limit the amount of cisplatin that patients could tolerate in the concurrent phase of treatment.

Pharmacokinetic interactions between HIV antiretroviral therapy and drugs used to treat opioid dependence.

Injection drug use is a common risk factor for HIV infection, and opioid use and dependence is the underlying condition that often fuels HIV risk behaviour and subsequent HIV seroconversion among injection drug users (IDUs). Treatment of opioid dependence often requires continued opioid administration in the form of substitution therapy, which means that opioid-using IDUs often continue receiving opioids even after cessation of illicit drug use. The concurrent use of both antiretrovirals and opioids in HIV-positive individuals is thus common.

Neighborhood and HIV infection among IDU: place of residence independently predicts HIV infection among a cohort of injection drug users.

This study was undertaken to investigate geographic residence in Vancouver's Downtown Eastside (DTES), Canada's poorest urban neighborhood, as an environmental risk factor for HIV infection among a cohort of injection drug users. HIV incidence rates were examined using Kaplan-Meier methods, and Cox proportional hazards regression was used to determine independent risk factors for HIV seroconversion. After intensive multivariate adjustment, DTES residence remained an independent predictor of HIV seroconversion (relative hazard=2.