Child Mortality, Hypothalamic-Pituitary-Adrenal Axis Activity and Cellular Aging in Mothers

Psychological challenges, including traumatic events, have been hypothesized to increase the age-related pace of biological aging. Here we test the hypothesis that psychological challenges can affect the pace of telomere attrition, a marker of cellular aging, using data from an ongoing longitudinal-cohort study of Kaqchikel Mayan women living in a population with a high frequency of child mortality, a traumatic life event. Specifically, we evaluate the associations between child mortality, maternal telomere length and the mothers’ hypothalamic-pituitary-adrenal axis (HPAA), or stress axis, activity. Child mortality data were collected in 2000 and 2013. HPAA activity was assessed by quantifying cortisol levels in first morning urinary specimens collected every other day for seven weeks in 2013. Telomere length (TL) was quantified using qPCR in 55 women from buccal specimens collected in 2013. Results: Shorter TL with increasing age was only observed in women who experienced child mortality (p = 0.015). Women with higher average basal cortisol (p = 0.007) and greater within-individual variation (standard deviation) in basal cortisol (p = 0.053) presented shorter TL. Non-parametric bootstrapping to estimate mediation effects suggests that HPAA activity mediates the effect of child mortality on TL. Our results are, thus, consistent with the hypothesis that traumatic events can influence cellular aging and that HPAA activity may play a mediatory role. Future large-scale longitudinal studies are necessary to confirm our results and further explore the role of the HPAA in cellular aging, as well as to advance our understanding of the underlying mechanisms involved

Physical Activity for Brain Health in Older Adults

Physical activity is a promising strategy for dementia prevention and disease modification. Here, we provide a narrative review the current evidence from epidemiological and intervention studies on the role of physical activity and exercise in promoting cognitive health in older adults both without and with cognitive impairment. We highlight some of the potential underlying mechanisms and discuss biological sex as a potential moderating factor. We conclude with limitations and future directions for this rapidly expanding line of research.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Endocrine substrates of cognitive and affective changes during pregnancy and postpartum

Pregnancy and motherhood constitute periods of tremendous hormonal variation that orchestrate parturition, lactation, maternal care and aggression, and recognition of offspring, among other functions. Cognitive processing also varies during pregnancy and motherhood and may serve an adaptive function in preparation for parturition and rearing. Additionally, maternal experience may have enduring consequences for the brain, behavior and cognition long after offspring are mature. However, the early postpartum period also renders women vulnerable as approximately 15% of women experience postpartum depression, with estimates of 50 - 80% reporting a milder form of depression termed ‘maternal blues.’ This review will present literature on pregnancy- and parity- related changes in both cognition and affect and how these changes likely involve plastic changes within the hippocampus, a region that is sensitive to reproductive hormones. Further, this review will discuss steroid and peptide hormones that may contribute to affective and cognitive disruptions during pregnancy and postpartum. Research in this area may reveal insight into how pregnancy and motherhood alter the likelihood of developing postpartum depression and related disorders.Arts, Faculty ofMedicine, Faculty ofPsychology, Department ofReviewedFacultyPostdoctora

Effects of computerized cognitive training on neuroimaging outcomes in older adults: a systematic review

Background: Worldwide, the population is aging and the number of individuals diagnosed with dementia is rising rapidly. Currently, there are no effective pharmaceutical cures. Hence, identifying lifestyle approaches that may prevent, delay, or treat cognitive impairment and dementia in older adults is becoming increasingly important. Computerized Cognitive Training (CCT) is a promising strategy to combat cognitive decline. Yet, the underlying mechanisms of the effect of CCT on cognition remain poorly understood. Hence, the primary objective of this systematic review was to examine peer-reviewed literature ascertaining the effect of CCT on both structural and functional neuroimaging measures among older adults to gain insight into the underlying mechanisms by which CCT may benefit cognitive function. Methods: In accordance with PRISMA guidelines, we used the following databases: MEDLINE, EMBASE, and CINAHL. Two independent reviewers abstracted data using pre-defined terms. These included: main study characteristics such as the type of training (i.e., single- versus multi-domain), participant demographics (age ≥ 50 years; no psychiatric conditions), and the inclusion of neuroimaging outcomes. The Physiotherapy Evidence Database (PEDro) scale was used to assess quality of all studies included in this systematic review. Results: Nine studies were included in this systematic review, with four studies including multiple MRI sequences. Results of this systematic review are mixed: CCT was found to increase and decrease both brain structure and function in older adults. In addition, depending on region of interest, both increases and decreases in structure and function were associated with behavioural performance. Conclusions: Of all studies included in this systematic review, results from the highest quality studies, which were two randomized controlled trials, demonstrated that multi-domain CCT could lead to increases in hippocampal functional connectivity. Further high quality studies that include an active control, a sample size calculation, and an appropriate training dosage, are needed to confirm these findings and their relation to cognition.Medicine, Faculty ofOther UBCPhysical Therapy, Department ofReviewedFacult

Refining sleep measurement using the Motionwatch8©: how many days of monitoring do we need to get reliable estimates of sleep quality for older adults with mild cognitive impairment?

Background: Poor sleep is common among older adults with mild cognitive impairment (MCI)—a transition stage between healthy cognition and dementia. Objective, reliable, and low-burden field methods to measure older adult sleep are also currently needed. The MotionWatch8© (MW8) wrist-worn actigraph provides estimates of sleep with 14 days of observation; however, there may be underlying differences in the reliability of sleep estimates based on MCI status. We therefore investigated the number of MW8 monitoring days required to estimate sleep in older adults with MCI and without. Methods: Older adults (55+ years; N = 151) wore the MW8 for ≥14 days. The Montreal Cognitive Assessment was used to categorize participants with probable MCI (scores of < 26/30) and participants without MCI (≥ 26/30). We calculated intra-class reliability coefficients for one, seven, and 14 days of wear-time, and performed Spearman-Brown predictions to determine the number of monitoring days needed for an ICC = 0.80. Results: Older adults with MCI were older (p < 0.01), more likely to be male (p = 0.03), and had shorter sleep duration (p < 0.01). Spearman-Brown analyses indicated that the number of monitoring days needed for an ICC = 0.80 in older adults with probable MCI was 7 days for sleep duration, 4 days for fragmentation, and 4 days for efficiency; adults without MCI required 4 days for duration, 6 days for fragmentation, and 3 days for efficiency. Conclusions: Our results indicate that while the reliability of MW8 estimates of sleep differs based on cognitive status, 7 days of MW8 monitoring provides reliable estimates of sleep for adults with MCI and those without.Medicine, Faculty ofOther UBCPhysical Therapy, Department ofReviewedFacult

Sex differences in neurogenesis and activation of new neurons in response to spatial learning

Adult hippocampal neurogenesis is often associated with hippocampus-dependent learning and memory. Throughout a new neuron’s development, it is differentially sensitive to factors that can influence its survival and functionality. Previous research shows that, spatial training that occurred 6 to 10 days after an injection of the DNA synthesis marker, bromodeoxyuridine (BrdU), increased cell survival in male rats. Because sex differences in spatial cognition and hippocampal neurogenesis have been reported, it is unclear whether spatial training would influence hippocampal neurogenesis in the same way in males and females. Therefore, this study examined sex differences in hippocampal neurogenesis following training in a spatial task. Male and female rats were trained in the spatial or cued version of the Morris water maze task 6 to 10 days after one injection of BrdU (200mg/kg). Twenty days following BrdU injection, all animals were given a probe trial and perfused. Males performed better in the spatial, but not cue, task than females. Spatial training increased BrdU-labeled cells relative to cue training only in males, but both males and females showed greater activation of new cells (BrdU co-labeled with immediate early gene product zif268) after spatial training compared to cue training. Furthermore, performance during spatial training was positively correlated with cell activation in females but not males. This study shows that while spatial training differentially regulates hippocampal neurogenesis in males and females, the activity of new neurons in response to spatial memory retrieval is similar. These findings highlight the importance of sex on neural plasticity and cognition.Arts, Faculty ofOther UBCNon UBCPsychology, Department ofReviewedFacult