We aimed to establish the treatment effect of physical activity for depression in young people through meta-analysis. Four databases were searched to September 2016 for randomised controlled trials of physical activity interventions for adolescents and young adults, 12–25 years, experiencing a diagnosis or threshold symptoms of depression. Random-effects meta-analysis was used to estimate the standardised mean difference (SMD) between physical activity and control conditions. Subgroup analysis and meta-regression investigated potential treatment effect modifiers. Acceptability was estimated using dropout. Trials were assessed against risk of bias domains and overall quality of evidence was assessed using GRADE criteria. Seventeen trials were eligible and 16 provided data from 771 participants showing a large effect of physical activity on depression symptoms compared to controls (SMD = −0.82, 95% CI = −1.02 to −0.61, p < 0.05, I2 = 38%). The effect remained robust in trials with clinical samples (k = 5, SMD = −0.72, 95% CI = −1.15 to −0.30), and in trials using attention/activity placebo controls (k = 7, SMD = −0.82, 95% CI = −1.05 to −0.59). Dropout was 11% across physical activity arms and equivalent in controls (k = 12, RD = −0.01, 95% CI = −0.04 to 0.03, p = 0.70). However, the quality of RCT-level evidence contributing to the primary analysis was downgraded two levels to LOW (trial-level risk of bias, suspected publication bias), suggesting uncertainty in the size of effect and caution in its interpretation. While physical activity appears to be a promising and acceptable intervention for adolescents and young adults experiencing depression, robust clinical effectiveness trials that minimise risk of bias are required to increase confidence in the current finding. The specific intervention characteristics required to improve depression remain unclear, however best candidates given current evidence may include, but are not limited to, supervised, aerobic-based activity of moderate-to-vigorous intensity, engaged in multiple times per week over eight or more weeks. Further research is needed. (Registration: PROSPERO-CRD 42015024388).

Over the last two decades, there has been a rapid increase of studies testing the efficacy and acceptability of virtual reality in the assessment and treatment of mental health problems. This systematic review was carried out to investigate the use of virtual reality in the assessment and the treatment of psychosis. Web of Science, PsychInfo, EMBASE, Scopus, ProQuest and PubMed databases were searched, resulting in the identification of 638 articles potentially eligible for inclusion; of these, 50 studies were included in the review. The main fields of research in virtual reality and psychosis are: safety and acceptability of the technology; neurocognitive evaluation; functional capacity and performance evaluation; assessment of paranoid ideation and auditory hallucinations; and interventions. The studies reviewed indicate that virtual reality offers a valuable method of assessing the presence of symptoms in ecologically valid environments, with the potential to facilitate learning new emotional and behavioural responses. Virtual reality is a promising method to be used in the assessment of neurocognitive deficits and the study of relevant clinical symptoms. Furthermore, preliminary findings suggest that it can be applied to the delivery of cognitive rehabilitation, social skills training interventions and virtual reality-assisted therapies for psychosis. The potential benefits for enhancing treatment are highlighted. Recommendations for future research include demonstrating generalisability to real-life settings, examining potential negative effects, larger sample sizes and long-term follow-up studies. The present review has been registered in the PROSPERO register: CDR 4201507776.

In the face of shifting demographics and an increase in human longevity, it is important to examine carefully what is known about cognitive ageing, and to identify and promote possibly malleable lifestyle and health-related factors that might mitigate age-associated cognitive decline. The Lothian Birth Cohorts of 1921 (LBC1921, n = 550) and 1936 (LBC1936, n = 1091) are longitudinal studies of cognitive and brain ageing based in Scotland. Childhood IQ data are available for these participants, who were recruited in later life and then followed up regularly. This overview summarises some of the main LBC findings to date, illustrating the possible genetic and environmental contributions to cognitive function (level and change) and brain imaging biomarkers in later life. Key associations include genetic variation, health and fitness, psychosocial and lifestyle factors, and aspects of the brain's structure. It addresses some key methodological issues such as confounding by early-life intelligence and social factors and emphasises areas requiring further investigation. Overall, the findings that have emerged from the LBC studies highlight that there are multiple correlates of cognitive ability level in later life, many of which have small effects, that there are as yet few reliable predictors of cognitive change, and that not all of the correlates have independent additive associations. The concept of marginal gains, whereby there might be a cumulative effect of small incremental improvements across a wide range of lifestyle and health-related factors, may offer a useful way to think about and promote a multivariate recipe for healthy cognitive and brain ageing.

Genetic influences play a significant role in risk for psychiatric disorders, prompting numerous endeavors to further understand their underlying genetic architecture. In this paper, we summarize and review evidence from traditional twin studies and more recent genome-wide molecular genetic analyses regarding two important issues that have proven particularly informative for psychiatric genetic research. First, emerging results are beginning to suggest that genetic risk factors for some (but not all) clinically diagnosed psychiatric disorders or extreme manifestations of psychiatric traits in the population share genetic risks with quantitative variation in milder traits of the same disorder throughout the general population. Second, there is now evidence for substantial sharing of genetic risks across different psychiatric disorders. This extends to the level of characteristic traits throughout the population, with which some clinical disorders also share genetic risks. In this review, we summarize and evaluate the evidence for these two issues, for a range of psychiatric disorders. We then critically appraise putative interpretations regarding the potential meaning of genetic correlation across psychiatric phenotypes. We highlight several new methods and studies which are already using these insights into the genetic architecture of psychiatric disorders to gain additional understanding regarding the underlying biology of these disorders. We conclude by outlining opportunities for future research in this area.

Motivational impairment is a common feature of both depression and psychosis; however, the psychological and neural mechanisms that give rise to motivational impairment in these disorders are poorly understood. Recent research has suggested that aberrant effort-cost decision-making (ECDM) may be a potential contributor to motivational impairment in both psychosis and depression. ECDM refers to choices that individuals make regarding the amount of ‘work’ they are willing to expend to obtain a certain outcome or reward. Recent experimental work has suggested that those with psychosis and depression may be less willing to expend effort to obtain rewards compared with controls, and that this effort deficit is related to motivational impairment in both disorders. In the current review, we aim to summarize the current literature on ECDM in psychosis and depression, providing evidence for transdiagnostic impairment. Next, we discuss evidence for the hypothesis that a seemingly similar behavioral ECDM deficit might arise from disparate psychological and neural mechanisms. Specifically, we argue that effort deficits in psychosis might be largely driven by deficits in cognitive control and the neural correlates of cognitive control processes, while effort deficits in depression might be largely driven by reduced reward responsivity and the associated neural correlates of reward responsivity. Finally, we will provide some discussion regarding future directions, as well as interpretative challenges to consider when examining ECDM transdiagnostically.

Psychotic experiences (PEs), including hallucination- and delusion-like experiences, are robustly associated with self-injurious thoughts and behaviours (SITB) in the general population. However, it remains unclear as to why there is an association. The purpose of this systematic review was to elucidate the role of other factors that influence the association between PEs and SITB and, in doing so, highlight potential mechanisms underlying the relationship. A search of electronic international databases was undertaken, including PubMed, PsycINFO and EMBASE, and eligible studies were grouped according to seven confounder categories: sociodemographics, mental disorders, alcohol and substance use, environmental, psychological, intervention and family history/genetic factors. The systematic search strategy identified 41 publications reporting on 1 39 427 participants from 16 different countries. In the majority of studies, where adjustment for other variables occurred, the association between PEs and SITB persisted, suggesting PEs have an independent role. Common mental disorders, psychological distress and negative environmental exposures explained a substantial amount of the variance and therefore need to be considered as potential underlying mechanisms. There was high variability in the variables adjusted for in these studies, and so the question still remains as to whether the association between PEs and self-harm/suicidality can be attributed (fully or in part) to confounding and mediating factors or directly causal mechanisms. Regardless of causality, the now extensive literature reporting an association between these two clinical phenomena supports the broad usefulness of PEs as an indicator of risk for SITB.

Current policy emphasises the importance of ‘living well’ with dementia, but there has been no comprehensive synthesis of the factors related to quality of life (QoL), subjective well-being or life satisfaction in people with dementia. We examined the available evidence in a systematic review and meta-analysis. We searched electronic databases until 7 January 2016 for observational studies investigating factors associated with QoL, well-being and life satisfaction in people with dementia. Articles had to provide quantitative data and include ⩾75% people with dementia of any type or severity. We included 198 QoL studies taken from 272 articles in the meta-analysis. The analysis focused on 43 factors with sufficient data, relating to 37639 people with dementia. Generally, these factors were significantly associated with QoL, but effect sizes were often small (0.1–0.29) or negligible (<0.09). Factors reflecting relationships, social engagement and functional ability were associated with better QoL. Factors indicative of poorer physical and mental health (including depression and other neuropsychiatric symptoms) and poorer carer well-being were associated with poorer QoL. Longitudinal evidence about predictors of QoL was limited. There was a considerable between-study heterogeneity. The pattern of numerous predominantly small associations with QoL suggests a need to reconsider approaches to understanding and assessing living well with dementia.

Help-seeking is important to access appropriate care and improve mental health. However, individuals often delay or avoid seeking help for mental health problems. Interventions to improve help-seeking have been developed, but their effectiveness is unclear. A systematic review and meta-analysis were therefore conducted to examine the effectiveness of mental health related help-seeking interventions. Nine databases in English, German and Chinese were searched for randomised and non-randomised controlled trials. Effect sizes were calculated for attitudes, intentions and behaviours to seek formal, informal and self-help. Ninety-eight studies with 69 208 participants were included. Interventions yielded significant short-term benefits in terms of formal help-seeking, self-help, as well as mental health literacy and personal stigma. There were also positive long-term effects on formal help-seeking behaviours. The most common intervention types were strategies to increase mental health literacy, destigmatisation (both had positive short-term effects on formal help-seeking behaviours) as well as motivational enhancement (with positive long-term effects on formal help-seeking behaviours). Interventions improved formal help-seeking behaviours if delivered to people with or at risk of mental health problems, but not among children, adolescents or the general public. There was no evidence that interventions increased the use of informal help. Few studies were conducted in low- and middle-income countries (LMICs). This study provides evidence for the effectiveness of help-seeking interventions in terms of improving attitudes, intentions and behaviours to seek formal help for mental health problems among adults. Future research should develop effective interventions to improve informal help-seeking, for specific target groups and in LMICs settings.

False positive findings in science are inevitable, but are they particularly common in psychology and psychiatry? The evidence that we review suggests that while not restricted to our field, the problem is acute. We describe the concept of researcher ‘degrees-of-freedom’ to explain how many false-positive findings arise, and how the various strategies of registration, pre-specification, and reporting standards that are being adopted both reduce and make these visible. We review possible benefits and harms of proposed statistical solutions, from tougher requirements for significance, to Bayesian and machine learning approaches to analysis. Finally we consider the organisation and methods for replication and systematic review in psychology and psychiatry.

Paranoid ideation is a core feature of psychosis, and models of paranoia have long proposed that it arises in the context of disturbances in the perception of the self. However, to develop targeted interventions, there is a benefit in clarifying further, which aspects of self-perception are implicated. Interpersonal sensitivity is a personality trait which has been associated with the risk of paranoid thinking in the general population. However, not all studies have found this link. We aimed to review the empirical literature assessing the association between interpersonal sensitivity and paranoia in both general population and clinical samples; and to explore if associations found differed depending on whether state or trait paranoia was assessed. The review followed PRISMA guidelines. Articles were identified through a literature search in OVID (PsychINFO, MEDLINE) and Web of Science up to December 2016. Fourteen studies with a total of 12 138 participants were included. All studies were of ‘fair’ or ‘good’ quality. A robust association was found between interpersonal sensitivity and paranoia in clinical and general population samples alike, regardless of the method of assessment of both paranoia and interpersonal sensitivity. Although this finding was more pronounced in studies of trait paranoia, it is likely that differences in study purpose, measurement, and power explain these differences. Findings from this review support the hypothesis that feelings of personal vulnerability and exaggerated socially evaluative concerns are central for both onset and maintenance of paranoid symptoms, suggesting avenues for future research in targeted interventions.

Since the seminal study of Steinbeck and Durell (1968), few epidemiological studies have attempted to replicate whether psychosocial stress precipitates the onset of a first psychotic episode. Our aim was to support or refute the finding of elevated psychosis incidence in the first month of army induction and to examine factors impacting the timing of onset. Data were collected from medical files of 186 army conscripts, hospitalized with a diagnosis of First Episode Psychosis (FEP) between 2005 and 2014 in the Psychiatric Military Hospital in Athens, Greece. FEP rates were at least 4.5 times higher in the first month of military service, compared with any other month. Earlier FEP onset was associated with rural environment at the time of birth, multiple drug use and service away from home. Psychosocial stress precipitates FEP, particularly in those exposed to other risk factors.