To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Plums are abundant in bioactive compounds which have been associated with numerous health benefits. In the present study, we aimed at examining the impact of plum supplementation on lipid profile of individuals. Electronic bibliographical databases were searched for relevant randomised clinical trials. Articles meeting our eligibility criteria were included for data extraction and final analysis. Weighted mean difference (WMD) was estimated using a random-effect model. Of the total articles retrieved in the initial search, nine articles were found to be eligible to be included in the analysis. Our results show that plum supplementation significantly improves total cholesterols levels in the unhealthy individuals. Moreover, plum supplementation reduces the LDL-c levels in the pooled sample (WMD = −11⋅52 mg/dl; 95 % CI −21⋅93, −1⋅11, P = 0⋅03, I2 = 98⋅7 %) and also in some of the subgroups of individuals (dried plum, unhealthy subjects, duration more than 8 weeks). Moreover, it had a significant reducing effect on TC levels just in unhealthy subjects. Although plum supplementation did not have any significant impact on serum levels of TG nor HDL-c. Our results show that supplementation with plums is potentially effective in reducing serum total cholesterol and LDL-c.
Meta-analysis provides a tool to statistically aggregate data from existing randomised controlled animal experiments. The results can then be summarised across a range of conditions and an increased pool of experimental data can be subjected to statistical analysis. New information can be derived, but most frequently the results are a refinement of existing knowledge. By designing experiments and reporting protocols, so that they have the capability of being useful to meta-analyses, maximum benefit can be derived from individual randomised controlled experiments, which may individually have little statistical power, and new avenues for productive research identified. The methodology for meta-analysis is derived from clinical trials in the medical sciences. Now that there is substantial output from animal science experiments, there is an opportunity to apply the technique to these and reduce the need for further experimentation. This paper describes the contribution of meta-analysis to the reduction of animals in research and provides details on data collection, analysis, the models used, and on interpreting and reporting the results. Three applications of meta-analysis to the field of animal science are also briefly described. First, the impact of undernutrition on the production and composition of milk from dairy cows confirmed existing knowledge about partitioning scarce nutrients to milk yield and live weight. Second, increased absorption of cadmium — a widespread toxic element — from organic sources was detected in sheep, which was previously untested. Third, no significant relationships were found between common indicators of undernutrition and weight, and condition score in cattle suggesting that the common indicators used are not suitable as evidence of long term undernutrition. This paper concludes that opportunities exist to increase the information gained from animal experiments by subjecting the results to meta-analysis, particularly if this can be anticipated in advance of study protocols being constructed.
In the past 10 years an increasing number of randomised trials have examined the effects of transdiagnostic treatments of patients with depression or anxiety. We conducted the first comprehensive meta-analysis of the outcomes of this emerging field.
We used the searches in PubMed, PsychINFO, Embase and the Cochrane library of an existing database of randomised trials of psychological interventions for depression to identify studies comparing a transdiagnostic treatment of patients with depression or anxiety with a control group (deadline 1 January 2022). We conducted random-effects meta-analyses and examined the effects on depression and anxiety at the short and longer term.
We included 45 randomised controlled trials with 51 comparisons between a psychotherapy and a control group and 5530 participants. Thirty-five (78%) studies were conducted in the last 10 years. The overall effect size was g = 0.54 (95% CI 0.40–0.69; NNT = 5.87), with high heterogeneity (I2 = 78; 95% CI 71–83), and a broad PI (−0.31–1.39). The effects remained significant in a series of sensitivity analyses, including exclusion of outliers, adjustment for publication bias, for studies with low risk of bias, and in multilevel analyses. The results were comparable for depression and anxiety separately. At 6 months after randomisation the main effects were still significant, but not at 12 months, although the number of studies was small.
Transdiagnostic treatments of patients with depression or anxiety are increasingly examined and are probably effective at the short term.
Extensive research has shown abnormal cerebral blood flow (CBF) in patients with major depressive disorder (MDD) that is a heritable disease. The objective of this study was to investigate the genetic mechanisms of CBF abnormalities in MDD.
To achieve a more thorough characterization of CBF changes in MDD, we performed a comprehensive neuroimaging meta-analysis of previous literature as well as examined group CBF differences in an independent sample of 133 MDD patients and 133 controls. In combination with the Allen Human Brain Atlas, transcriptome-neuroimaging spatial association analyses were conducted to identify genes whose expression correlated with CBF changes in MDD, followed by a set of gene functional feature analyses.
We found increased CBF in the reward circuitry and default-mode network and decreased CBF in the visual system in MDD patients. Moreover, these CBF changes were spatially associated with expression of 1532 genes, which were enriched for important molecular functions, biological processes, and cellular components of the cerebral cortex as well as several common mental disorders. Concurrently, these genes were specifically expressed in the brain tissue, in immune cells and neurons, and during nearly all developmental stages. Regarding behavioral relevance, these genes were associated with domains involving emotion and sensation. In addition, these genes could construct a protein-protein interaction network supported by 60 putative hub genes with functional significance.
Our findings suggest a cerebral perfusion redistribution in MDD, which may be a consequence of complex interactions of a wide range of genes with diverse functional features.
Polycystic ovary syndrome (PCOS) is one of the most common endocrine diseases characterised by unusual levels of sex hormones and dysfunction of the ovaries. The infertility rate is high among patients with PCOS. Unusual hormonal status can lead to the inability of ovaries to release functional and mature follicles. Clinical trials on the effects of N-acetylcysteine (NAC) supplementation on ovulation and sex hormones profile in women with PCOS have been controversial. We performed a systematic review and meta-analysis to evaluate the potential effects of NAC supplementation on ovulation and sex hormones profile. PubMed, Scopus, Embase, Web of Science and Cochrane Central library international databases were searched till September 2021. Meta-analysis was performed using a random-effects approach in case of significant between-study heterogeneity. Eighteen studies, including 2185 participants, were included in the present meta-analysis. NAC significantly reduced total testosterone (TT) levels (standardised mean difference (SMD): −0·25 ng/ml; 95 % CI (−0·39, −0·10); ‘P < 0·001’, I2 = 53·9 %, P = 0·034) and increased follicle-stimulating hormone (FSH) levels (SMD: 0·39 mg/ml; 95 % CI (0·07, 0·71); P = 0·01, I2 = 70·9 %, P = 0·002). Oestrogen levels also increased after correcting publication bias. However, no significant effect was observed on the number of follicles, endometrial thickness, progesterone, serum luteinising hormone levels and sex hormone-binding globulin. The results indicated that NAC supplementation decreased TT levels and increased FSH levels. Overall, NAC supplementation might be effective in the improvement of reproductive system function in patients with PCOS.
Survivors of intimate partner violence (IPV) are at risk for serious health consequences, and providing effective psychosocial interventions to support these individuals is a major global health challenge. Previous systematic reviews and meta-analyses in this field do not allow for clear conclusions about the efficacy of these interventions, owing to a narrow focus on specific subpopulations or intervention formats. This protocol presents a systematic review and meta-analysis, which will provide a comprehensive overview of the empirical evidence of various psychosocial interventions for survivors of IPV and investigate their efficacy in improving safety-related, mental health and psychosocial outcomes both overall and within homogeneous subgroups (trial registration: https://osf.io/4gp95). We will systematically search the literature databases PsycInfo, MEDLINE, Embase and CENTRAL. Randomised controlled trials evaluating the efficacy of psychosocial interventions in increasing the safety or mental health of IPV survivors compared with a control group will be eligible. We will extract relevant data from eligible studies and assess study quality using the Cochrane Risk of Bias 2 (RoB 2) tool. We will qualitatively summarise the results and we will calculate weighted effect sizes under random effect model assumption for the primary outcomes IPV, depression and post-traumatic stress disorder. We will perform subgroup analyses to investigate the moderating effects of theoretical basis, delivery mode, intensity and setting of psychosocial interventions. The resultant overview of the current body of evidence for psychosocial interventions for IPV survivors is intended to inform future research and practice.
It is a long known problem that the preferential publication of statistically significant results (publication bias) may lead to incorrect estimates of the true effects being investigated. Even though other research areas (e.g., medicine, biology) are aware of the problem, and have identified strong publication biases, researchers in judgment and decision making (JDM) largely ignore it. We reanalyzed two current meta-analyses in this area. Both showed evidence of publication biases that may have led to a substantial overestimation of the true effects they investigated. A review of additional JDM meta-analyses shows that most meta-analyses conducted no or insufficient analyses of publication bias. However, given our results and the rareness of non-significant effects in the literature, we suspect that biases occur quite often. These findings suggest that (a) conclusions based on meta-analyses without reported tests of publication bias should be interpreted with caution and (b) publication policies and standard research practices should be revised to overcome the problem.
Previous research has shown that short-term changes in blood glucose influence our preferences and may affect decisions about risk as well. However, consensus is lacking about whether and how blood glucose influences decision making under risk, and we conduct two experiments and a meta-analysis to examine this question in detail. In Study 1, using a pecuniary valuation method, we find no effect of blood glucose on willingness to pay for risky products that may act as allergens. In Study 2, using risky gambles, we find that low levels of blood glucose increase risk taking for food and to a lesser degree for non-food rewards. Combining our own and previous findings in a meta-analysis, we show that low levels of blood glucose on average increase risk taking about food. Low blood glucose does not increase risk taking about non-food rewards although this is subject to heterogeneity. Overall, our studies suggest that low blood glucose increases our willingness to gamble on how much food we can get, but not our willingness to eat food that can harm us. Our findings are best explained by the energy budget rule.
Although the number of rabbits (Oryctolagus cuniculus) produced in Europe is important, they are under-represented in welfare research. Studies on the effects of housing conditions have focused on performance and mortality. We conducted a meta-analysis to further understand the impact of the housing environment on growing rabbits. Whilst providing a robust quantifiable review, meta-analyses are restricted to existing literature. We included information on behaviour, mortality and performance. Twenty-seven peer-reviewed and conference publications, with a total of 99 experimental treatments, were used. We collected information about rabbit age, bodyweight, sex and breed; allometric space allowance, pen height, group size, environmental temperature, floor type, substrate and enrichment use, lighting, diet and medicated feed. Predictive equations for each response variable were calculated using multiple regression models. Higher space allowance was found to increase locomotor and social activity, and to reduce resting and comfort behaviour. Restricted pen height increased ingestive behaviour; comfort behaviours decreased as space allowance increased, although these might have been confounded with self-directed behaviours in literature. Mortality remained stable at varying space allowances, but increased with larger group sizes and enrichment objects. Growth rate, feed intake and feed conversion were reduced with higher space allowances and larger group sizes, and by provision of substrate and enrichment objects. Findings suggest that higher space allowance and unrestricted pen height are beneficial for rabbit behaviour, but might have undesired consequences if considered independent from other aspects. The challenge of promoting welfare in commercial conditions was highlighted, as a number of parameters which improved behavioural expression reduced performance. In certain cases welfare inputs complemented performance, including providing non-medicated feed and higher space allowance in cooler climates. Although our results should be interpreted with caution given the limitations of the included variables, they are expected to contribute to the improvement of current and new rabbit housing systems to optimise welfare.
Ninety-eight Australian students participated in a functional replication of a study published by Dijksterhuis et al. (2006). The results indicated that unconscious thought does not necessarily lead to better normative decision making performance than conscious thought, which is contrary to the results found in Dijksterhuis et al. Since other studies showed a positive, though statistically not significant, effect for unconscious thought, a meta-analysis comprising a total of 17 experiments was conducted. It suggests that there is little evidence for an advantage to normative decision making using unconscious thought. However, a discussion of potential moderators shows that further study would help to identify situations in which unconscious thought is truly helpful and those in which it is not.
Are difficult decisions best made after a momentary diversion of thought? Previous research addressing this important question has yielded dozens of experiments in which participants were asked to choose the best of several options (e.g., cars or apartments) either after conscious deliberation, or after a momentary diversion of thought induced by an unrelated task. The results of these studies were mixed. Some found that participants who had first performed the unrelated task were more likely to choose the best option, whereas others found no evidence for this so-called unconscious thought advantage (UTA). The current study examined two accounts of this inconsistency in previous findings. According to the reliability account, the UTA does not exist and previous reports of this effect concern nothing but spurious effects obtained with an unreliable paradigm. In contrast, the moderator account proposes that the UTA is a real effect that occurs only when certain conditions are met in the choice task. To test these accounts, we conducted a meta-analysis and a large-scale replication study (N = 399) that met the conditions deemed optimal for replicating the UTA. Consistent with the reliability account, the large-scale replication study yielded no evidence for the UTA, and the meta-analysis showed that previous reports of the UTA were confined to underpowered studies that used relatively small sample sizes. Furthermore, the results of the large-scale study also dispelled the recent suggestion that the UTA might be gender-specific. Accordingly, we conclude that there exists no reliable support for the claim that a momentary diversion of thought leads to better decision making than a period of deliberation.
The DOSPERT scale has been used extensively to understand individual differences in risk attitudes across varying decision domains since 2002. The present study reports a reliability generalization meta-analysis to summarize the internal consistency of both the initial and the revised versions of DOSPERT. It also examined factors that can influence the reliability of the DOSPERT and its subscales. A total of 104 samples (N = 30,109) that reported 465 coefficient alphas were analyzed. Results of meta-regression models showed that the overall coefficient alpha of the DOSPERT total scores was satisfactory, regardless of the scale and study characteristics. Coefficient alphas varied significantly across domain subscales, with values ranging from .68 for the social domain to .80 for the recreational domain. In addition, the alpha coefficients of subscales varied significantly depending on various study characteristics. Finally, we report the meta-analysis of the intercorrelations among DOSPERT subscales and reveal that intercorrelations among the subscales are heterogeneous. We discuss the theoretical implications of the present findings.
Are highly intelligent people less risk averse? Over the last two decades scholars have argued the existence of a negative relationship between cognitive ability and risk aversion. Although numerous studies support this, the link between cognitive ability and risk aversion has not been found consistently. To shed new light on this topic, a systematic review and meta-analysis was conducted. A total of 97 studies were identified and included for meta-analysis in the domain of gains (N=90, 723), 41 in the mixed domain (N=50, 936), and 12 in the domain of losses (N=4, 544). Results indicate that there exists a weak, but significant negative relationship between cognitive ability and risk aversion in the domain of gains. However, no relationship was observed in the mixed domain or in the domain of losses. Several meta-regressions were performed to investigate the influence of moderator variables. None of the moderator variables were found to consistently influence the relationship between cognitive ability and risk aversion across the domain of gains, mixed and losses. Moreover, no significant difference was observed between males and females across all three domains. In conclusion, this systematic review and meta-analysis provides new evidence that the relationship between cognitive ability and risk aversion is domain specific and not as strong as suggested by some previous studies.
Preferences about delayed rewards and preferences about risk are central to the literature on decision making. Several proposals suggest that such preferences arise from a single process and thus predict strong associations between preferences about delay and risk. Although there is a wealth of data on this association, the evidence is inconclusive; some studies have reported significant associations but many have not. Consequently, it is unclear whether the association between delay preferences and risk preferences is strong enough to support single-process theories. To further explore this question, we took a meta-analytic approach surveying 26 studies totaling 32 effect sizes. Results reveal a small to moderate association between risk preferences and delay preferences. This result provides little support for existing proposals because the observed relationship is no stronger than associations observed between either delay preferences or risk preferences and other variables. Moderating variables provide some explanation for inconsistencies across studies. Implications, including the apparent discrepancy between this literature and the conventional construct of impulsivity, are also discussed.
One of the many established predictors of conspiracy beliefs is reflective thinking, but no meta-analysis so far has examined this relationship. In the current meta-analysis of published and unpublished correlational data (145 samples, 181 effect sizes), we found a significant negative association between reflective thinking and conspiracy beliefs with a medium-level effect size (r = –.189) . Similar levels of correlations were found across different types of measures (self-report vs. performance-based) and conspiracy beliefs (generic vs. specific). Further, no evidence suggested publication bias in this body of work. Suggestions for future research are discussed.
We conducted a systematic review and meta-analysis on the association between nonword repetition (NWR) and language exposure in bilingual children and explored whether the association is influenced by other variables. We performed a blind literature review on ERIC and Google Scholar, a random-effects model meta-analysis and subgroup analyses to test potential moderators. Out of 822 screened articles, we identified 24 works including 1399 children. Significant associations were found using either cumulative or current exposure, language-like nonwords, phoneme NWR scoring, in children with typical language development. Nonsignificant associations were found in studies either using age of first exposure, on children older than six, with less than 50 participants, using NWR lists containing 16-24 nonwords or with participants having different native languages. Weak associations were found when considering whole-word scoring or gray literature. We highlight the contributions of different variables to NWR, and evidence to optimally design NWR for bilingual language assessment.
The associations of red/processed meat consumption and cancer-related health outcomes have been well discussed. The umbrella review aimed to summarise the associations of red/processed meat consumption and various non-cancer-related outcomes in humans. We systematically searched the systematic reviews and meta-analyses of associations between red/processed meat intake and health outcomes from PubMed, Embase, Web of Science and the Cochrane Library databases. The umbrella review has been registered in PROSPERO (CRD 42021218568). A total of 40 meta-analyses were included. High consumption of red meat, particularly processed meat, was associated with a higher risk of all-cause mortality, CVD and metabolic outcomes. Dose–response analysis revealed that an additional 100 g/d red meat intake was positively associated with a 17 % increased risk of type 2 diabetes mellitus (T2DM), 15 % increased risk of CHD, 14 % of hypertension and 12 % of stroke. The highest dose–response/50 g increase in processed meat consumption at 95 % confident levels was 1·37, 95 % CI (1·22, 1·55) for T2DM, 1·27, 95 % CI (1·09, 1·49) for CHD, 1·17, 95 % CI (1·02, 1·34) for stroke, 1·15, 95 % CI (1·11, 1·19) for all-cause mortality and 1·08, 95 % CI (1·02, 1·14) for heart failure. In addition, red/processed meat intake was associated with several other health-related outcomes. Red and processed meat consumption seems to be more harmful than beneficial to human health in this umbrella review. It is necessary to take the impacts of red/processed meat consumption on non-cancer-related outcomes into consideration when developing new dietary guidelines, which will be of great public health importance. However, more additional randomised controlled trials are warranted to clarify the causality.
Summarizing results from many studies has a long history and is currently a hot topic, largely as a result of the Evidence Based Medicine movement. This is treated in this chapter, starting with an early attempt by Karl Pearson at the beginning of the twentieth century. The statistical techniques of meta-analysis are described, as is the Cochrane Collaboration and its programme of summarizing results from clinical trials.
Dropout from psychotherapy for borderline personality disorder (BPD) is a notorious problem. We investigated whether treatment, treatment format, treatment setting, substance use exclusion criteria, proportion males, mean age, country, and other variables influenced dropout.
From Pubmed, Embase, Cochrane, Psycinfo and other sources, 111 studies (159 treatment arms, N = 9100) of psychotherapy for non-forensic adult patients with BPD were included. Dropout per quarter during one year of treatment was analyzed on participant level with multilevel survival analysis, to deal with multiple predictors, nonconstant dropout chance over time, and censored data. Multiple imputation was used to estimate quarter of drop-out if unreported. Sensitivity analyses were done by excluding DBT-arms with deviating push-out rules.
Dropout was highest in the first quarter of treatment. Schema therapy had the lowest dropout overall, and mentalization-based treatment in the first two quarters. Community treatment by experts had the highest dropout. Moreover, individual therapy had lowest dropout, group therapy highest, with combined formats in-between. Other variables such as age or substance-use exclusion criteria were not associated with dropout.
The findings do not support claims that all treatments are equal, and indicate that efforts to reduce dropout should focus on early stages of treatment and on group treatment.