Measuring Cortisol in the Classroom with School-Aged Children—A Systematic Review and Recommendations

The collection of salivary cortisol has been chosen as one of the least intrusive, easiest to collect, analyze, and store methods of obtaining information on physiological changes. It is, however, not clear what the best practice is when collecting salivary cortisol from children within the school setting. The aim of this systematic review is to evaluate the feasibility of cortisol collection in schools for future research and to make recommendations for best practice. The review included 25 peer-reviewed articles from seven databases. The hypotheses of the included studies vary, but they all use cortisol as a diurnal, baseline, or acute measure, or to measure the effect of an intervention. Two methods of salivary cortisol collection were preferred by most of the research, i.e., passive drool or cotton Salivettes. The review has concluded that cortisol is a physiological marker that can be successfully measured in school-based research. However, there are discrepancies across studies when evaluating the collection guidelines, protocols, and instructions to participants as well as transparency of the success rate of obtaining all samples. Recommendations are made for future research to address and avoid such discrepancies and improve cross-study comparisons by implementing standard protocol guidelines

Effects of exercise, cognitive, and dual-task interventions on cognition in type 2 diabetes mellitus: A systematic review and meta-analysis

Introduction: Previous evidence has shown significant effects of exercise, cognitive and dual-task training for improving cognition in healthy cohorts. The effects of these types of interventions in type 2 diabetes mellitus is unclear. The aim of this research was to systematically review evidence, and estimate the effect, of exercise, cognitive, and dual-task interventions on cognition in type 2 diabetes mellitus. Method: Electronic databases including PubMed, EMBASE, CINAHL, PsycINFO, SPORTDiscus, and MEDLINE were searched for ongoing and completed interventional trials investigating the effect of either an exercise, cognitive or dual-task intervention on cognition in type 2 diabetes mellitus. Results: Nine trials met the inclusion criteria – one dual-task, two cognitive, and six exercise. Meta-analyses of exercise trials showed no significant effects of exercise on measures of executive function (Stroop task, SMD= -0.31, 95% CI -0.71–0.09, P=0.13, trail making test part A SMD= 0.28, 95% CI -0.20–0.77 P=0.25, trail making test part B SMD= -0.15, 95% CI -0.64–0.34 P=0.54, digit symbol SMD= 0.09, 95% CI -0.39–0.57 P=0.72), and memory (immediate memory SMD= 0.20, 95% CI -0.28–0.69, P=0.41 and delayed memory SMD= -0.06, 95% CI -0.55–0.42, P=0.80). A meta-analysis could not be conducted using cognitive or dual-task data, but individual trials did report a favourable effect of interventions on cognition. Risk of bias was considered moderate to high for the majority of included trials. Conclusions: Meta-analyses of exercise trials identified a small effect size (0.31), which whilst not significant warrants further investigation. Larger and more robust trials are needed that report evidence using appropriate reporting guidelines (e.g. CONSORT) to increase confidence in the validity of results. Trial Registration: Protocol was registered (CRD42017058526) on the International Prospective Register of Systematic Reviews (http://www.crd.york.ac.uk/PROSPERO)

The effect of ANKK1 Taq1A and DRD2 C957T polymorphisms on executive function: a systematic review and meta-analysis

Research in healthy adults suggests that C957T polymorphism of the dopamine D2 receptor encoding DRD2 and the Taq1A polymorphism of the neighbouring gene ankyrin repeat and kinase domain containing 1 (ANKK1) alter dopaminergic signalling and may influence prefrontally-mediated executive functions. A systematic review and meta-analysis was carried out on the evidence for the association of DRD2 C957T and ANKK1 Taq1A polymorphisms in performance on tasks relating to the three core domains of executive function: working memory, response inhibition and cognitive flexibility in healthy adults. CINAHL, MEDLINE, PsycARTICLES and PsychINFO databases were searched for predefined key search terms associated with the two polymorphisms and executive function. Studies were included if they investigated a healthy adult population with the mean age of 18-65 years, no psychiatric or neurological disorder and only the healthy adult arm were included in studies with any case-control design. Data from 17 independent studies were included in meta-analysis, separated by the Taq1A and C957T polymorphisms and by executive function tests: working memory (Taq1A, 6 samples, n = 1270; C957 T, 6 samples, n = 977), cognitive flexibility (C957 T, 3 samples, n = 620), and response inhibition (C957 T, 3 samples, n = 598). The meta-analyses did not establish significant associations between these gene polymorphisms of interest and any of the executive function domains. Theoretical implications and methodological considerations of these findings are discussed

Interactive effects of early life stress and CACNA1C genotype on cortisol awakening response

The rs1006737 (A/G) single nucleotide polymorphism within the gene encoding the Cav1.2 subunit of the L-type voltage-dependent calcium channel (CACNA1C) has been strongly implicated in psychiatric disorders. In addition, calcium channels are sensitive to the effects of glucocorticoids and functional variation may contribute to altered stress responsivity. This study aimed to investigate the role of early life stress (ELS) and its interaction with CACNA1C rs1006737 in affecting the cortisol awakening response (CAR), an indicator of HPA-axis function. Salivary cortisol was measured in 103 healthy adult males (aged 21-63) on two consecutive days at awakening and 30 minutes later. The ELS measure investigated self-reported adverse life events prior to age 17. The results revealed a marginally significant main effect of CACNA1C, a significant main effect of ELS, and a significant genotype-by-ELS interaction on the CAR, whereby non-risk allele carriers (GG) who had experienced early adversity showed higher CAR compared to the other groups. Further exploratory analyses showed that this interaction may have arisen from individuals who had experienced ELS before adolescence (prior to age 13). This study is the first to provide evidence that the effect of ELS on CAR may be partially moderated via CACNA1C rs1006737 genotype, whereby the heightened CAR in the GG-ELS group may be an indicator of mental health resilience in response to ELS

The Effectiveness of School-Based Mindfulness and Cognitive Behavioural Programmes to Improve Emotional Regulation in 7–12-Year-Olds: A Systematic Review and Meta-Analysis

Objectives Though findings have been mixed, some primary or elementary school-based mindfulness and cognitive behavioural interventions have been shown to improve aspects of emotion regulation. Age is suggested as a potential mediator but previous reviews have not addressed this comprehensively, making evaluation of impact unclear. The current review brought together the evidence surrounding the impact of mindfulness-based interventions (MBIs) or cognitive behavioural interventions (CBIs) on emotion regulation in children aged between 7 and 12 years. Method Databases (British Education Index, Child Development and Adolescent Studies, CINAHL, Education Source, ERIC, MEDLINE, PsycINFO, PubMed, SAGE, Web of Science) were searched for published and unpublished randomised controlled trials evaluating the effect of primary school-based MBIs (n = 18) or CBIs (n = 12) on measures of emotional awareness, modulation and expression. Results Analysis of the MBIs in this review indicated a significant improvement in emotional awareness, an increase in positive emotions and a reduction in depression. Sub-analyses found an effect of age, duration and universal delivery for MBIs. Analysis of the CBIs indicated significant improvement in child negative expressive behaviours as reported by parents. Risk of bias was low across domains of incomplete outcome data and selective outcome reporting but was unclear in other domains. Conclusions Evidence from the MBI studies suggested that universal interventions with a shorter duration had more significant effects, particularly for 10–12-year-old participants. Future research should investigate programme design features and the suitability of content and skill-focus for different age groups, employing qualitative techniques for analysis. This could lead to reconsideration of typical intervention formats for primary school children. Pre-registration PROSPERO #CRD42019139283

The influence of REM sleep and SWS on emotional memory consolidation in participants reporting depressive symptoms

Negative emotional memory bias is thought to play a causal role in the onset and maintenance of major depressive disorder. Rapid Eye Movement (REM) sleep has been shown to selectively consolidate negative emotional memories in healthy participants, and is greater in quantity and density in depressed patients. Slow-Wave Sleep (SWS) is typically associated with the consolidation of non-emotional memories. However, the effects of REM sleep and SWS on emotional memory consolidation have not been investigated in participants reporting depressive symptoms. In this study, we recruited two groups of healthy participants; one reporting mild-to-moderate depressive symptoms, and another reporting minimal depressive symptoms (assessed using the Beck Depression Inventory; BDI-II). Using a within-subjects split-night design, we measured consolidation of positive, neutral and negative images across a 3 h retention interval rich in either REM sleep or SWS. We found a significant sleep condition x image valence interaction in participants reporting depressive symptoms [F (2, 20) = 4.73, p = .021], but not participants reporting minimal depressive symptoms [F (2, 22) = 0.17, p = .845]. Participants reporting depressive symptoms consolidated significantly more neutral memories during SWS, and marginally more negative memories during REM sleep, than those reporting minimal depressive symptoms [t (21) = 2.44, p = .023; t (21) = 1.96, p = .064, respectively]. Our preliminary results demonstrate that REM sleep and SWS have differential effects on the consolidation of emotional and neutral images in participants reporting depressive symptoms. Further studies including larger sample sizes are required to investigate whether REM sleep alterations promote the development of negative memory bias in major depressive disorder

Investigating the effect of exercise, cognitive and dual-task interventions upon cognitive function in type 2 diabetes mellitus: a systematic review and meta-analysis

Objectives/purpose: Whilst exercise, cognitive, and dual-task interventions have been shown to improve cognitive function within a healthy aging population, it remains unclear as to what effect such interventions may have in a type 2 diabetes mellitus (T2DM) population. Design: Systematic review/meta-analyses. Methods: Databases (PubMed, EMBASE, CINAHL, Web of Science, ClinicalTrial.gov, Cochrane register of controlled trials, Prospero, HTA, and DARE) of published, unpublished, and ongoing studies were searched for randomised controlled trials investigating the effect of exercise, cognitive and dual-task interventions upon cognitive function in T2DM. Results: This review identified three studies investigating the effects of an exercise intervention and one study investigating the effect of a cognitive intervention upon cognitive function in T2DM. Meta-analyses indicated a significant effect of exercise for improving global cognitive function (minimental state examination P<0.05) and inhibitory control (Stroop task P<0.05) but not working memory (digit symbol P=0.35). Calculated effect sizes of outcome measures in the cognitive study indicated a beneficial effect of cognitive training upon cognitive function in T2DM. The risk of bias assessment in this review was hindered predominantly by poor reporting practices of included studies. Due to incomplete reporting of 12 methodological procedures, two studies were judged to have a high risk of overall bias whilst the remaining two were judged as having a moderate overall risk of bias. Conclusions: The findings of the present systematic review and meta-analyses provide evidence for exercise and cognitive interventions improving cognitive function in T2DM. The poor reporting practices of included studies means that future research in this area should identify relevant reporting guidelines (e.g. CONSORT) to reduce the risk of bias and facilitate transparent reporting

CACNA1C methylation: association with cortisol, perceived stress, rs1006737 and childhood trauma in males

Aim: We investigated morning cortisol, stress, rs1006737 and childhood trauma relationship with CACNA1C methylation. Materials & Methods: Morning cortisol release, childhood trauma and perceived stress were collected and genotyping for rs1006737 conducted in 103 adult males. Genomic DNA extracted from saliva was bisulphite converted and using pyrosequencing methylation determined at 11 CpG sites within intron 3 of CACNA1C. Results: A significant negative correlation between waking cortisol and overall mean methylation was found and a positive correlation between CpG5 methylation and perceived stress. Conclusion: CACNA1C methylation levels may be related to cortisol release and stress perception. Future work should evaluate the influence of altered CACNA1C methylation on stress reactivity to investigate this as a potential mechanism for mental health vulnerability

Elevated cortisol awakening response associated with early life stress and impaired executive function in healthy adult males

Experiencing early life stress (ELS) and subsequent dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis may play a role in the aetiology of mental health disorders. However, the exact mechanisms linking HPAaxis dysregulation with the development of psychopathology have not been fully delineated. Progress in this area is hampered by the complex and often conflicting associations found between markers of HPA-axis function and risk factors for mental health disorders such as impaired executive function (EF) and ELS. This study investigated the association of the cortisol awakening response (CAR) with ELS and EF in a healthy adult male population (n =109, aged 21–63). As previous inconsistencies in CAR and ELS association studies may be the result of not considering ELS-related factors such as cumulative exposure, type of stressor and developmental timing of ELS, these were also investigated. The main findings were that the CAR was significantly elevated in individuals reporting ELS compared to those reporting no ELS (p =0.007) and that an elevated CAR predicted poorer problem solving/planning (p=0.046). Cumulative exposure, type of stressor and developmental timing of ELS were also found to impact significantly on the CAR. These results suggest that ELS is associated with chronic changes in HPA-axis function and that these changes may be associated with impairments in problem solving/ planning. Future work should investigate further the neurobiological mechanisms linking ELS, the CAR and EF and their role in conferring risk for the development of mental health disorders

The ‘affect tagging and consolidation’ (ATaC) model of depression vulnerability

Since the 1960’s polysomnographic sleep research has demonstrated that depressive episodes are associated with REM sleep alterations. Some of these alterations, such as increased REM sleep density, have also been observed in first-degree relatives of patients and remitted patients, suggesting that they may be vulnerability markers of major depressive disorder (MDD), rather than mere epiphenomena of the disorder. Neuroimaging studies have revealed that depression is also associated with heightened amygdala reactivity to negative emotional stimuli, which may also be a vulnerability marker for MDD. Several models have been developed to explain the respective roles of REM sleep alterations and negatively-biased amygdala activity in the pathology of MDD, however the possible interaction between these two potential risk-factors remains uncharted. This paper reviews the roles of the amygdala and REM sleep in the encoding and consolidation of negative emotional memories, respectively. We present our ‘affect tagging and consolidation’ (ATaC) model, which argues that increased REM sleep density and negatively-biased amygdala activity are two separate, genetically influenced risk-factors for depression which interact to promote the development of negative memory bias – a well-known cognitive vulnerability marker for depression. Predictions of the ATaC model may motivate research aimed at improving our understanding of sleep dependent memory consolidation in depression aetiology