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Background:
Several standards have been developed to assess methodological quality of systematic reviews (SR). One widely used tool is the AMSTAR. A recent update -AMSTAR 2 -is a 16 item evaluation tool that enables a detailed assessment of SR that include randomised (RCT) or non-randomised studies (NRS) of healthcare interventions.
Methods:
A cross-sectional study of SR on pharmacological or psychological interventions in major depression in adults was conducted. SR published during 2012-2017 were sampled from MEDLINE, EMBASE and the Cochrane Database of SR. Methodological quality was assessed using AMSTAR 2. Potential predictive factors associated with quality were examined.
Results:
In rating overall confidence in the results of 60 SR four reviews were rated "high", two were "moderate", one was "low" and 53 were "critically low". The mean AMSTAR 2 percentage score was 45.3% (standard deviation 22.6%) in a wide range from 7.1% to 93.8%. Predictors of higher quality were: type of review (higher quality in Cochrane Reviews), SR including only randomized trials and higher journal impact factor.
Limitations:
AMSTAR 2 is not intended to be used for the generation of a percentage score.
Conclusions:
According to AMSTAR 2 the overall methodological quality of SR on the treatment of adult major depression needs improvement. Although there is a high need for summarized information in the field of mental health, this work demonstrates the need to critically assess SR before using their findings. Better adherence to established reporting guidelines for SR is needed.
Working memory load-dependent brain response predicts behavioral training gains in older adults
(2014)
In the domain of working memory (WM), a sigmoid-shaped relationship between WM load and brain activation patterns has been demonstrated in younger adults. It has been suggested that age-related alterations of this pattern are associated with changes in neural efficiency and capacity. At the same time, WM training studies have shown that some older adults are able to increase their WM performance through training. In this study, functional magnetic resonance imaging during an n-back WM task at different WM load levels was applied to compare blood oxygen level-dependent (BOLD) responses between younger and older participants and to predict gains in WM performance after a subsequent 12-session WM training procedure in older adults. We show that increased neural efficiency and capacity, as reflected by more "youth-like" brain response patterns in regions of interest of the frontoparietal WM network, were associated with better behavioral training outcome beyond the effects of age, sex, education, gray matter volume, and baseline WM performance. Furthermore, at low difficulty levels, decreases in BOLD response were found after WM training. Results indicate that both neural efficiency (i. e., decreased activation at comparable performance levels) and capacity (i. e., increasing activation with increasing WM load) of a WM-related network predict plasticity of the WM system, whereas WM training may specifically increase neural efficiency in older adults.
Processing of reward is the basis of adaptive behavior of the human being. Neural correlates of reward processing seem to be influenced by developmental changes from adolescence to late adulthood. The aim of this study is to uncover these neural correlates during a slot machine gambling task across the lifespan. Therefore, we used functional magnetic resonance imaging to investigate 102 volunteers in three different age groups: 34 adolescents, 34 younger adults, and 34 older adults. We focused on the core reward areas ventral striatum (VS) and ventromedial prefrontal cortex (VMPFC), the valence processing associated areas, anterior cingulate cortex (ACC) and insula, as well as information integration associated areas, dorsolateral prefrontal cortex (DLPFC), and inferior parietal lobule (IPL). Results showed that VS and VMPFC were characterized by a hyperactivation in adolescents compared with younger adults. Furthermore, the ACC and insula were characterized by a U-shape pattern (hypoactivation in younger adults compared with adolescents and older adults), whereas the DLPFC and IPL were characterized by a J-shaped form (hyperactivation in older adults compared with younger groups). Furthermore, a functional connectivity analysis revealed an elevated negative functional coupling between the inhibition-related area rIFG and VS in younger adults compared with adolescents. Results indicate that lifespan-related changes during reward anticipation are characterized by different trajectories in different reward network modules and support the hypothesis of an imbalance in maturation of striatal and prefrontal cortex in adolescents. Furthermore, these results suggest compensatory age-specific effects in fronto-parietal regions. Hum Brain Mapp 35:5153-5165, 2014. (c) 2014 Wiley Periodicals, Inc.