Imaging of depressive disorders

2020 ◽  
pp. 797-806
Author(s):  
Guy M. Goodwin ◽  
Michael Browning
Keyword(s):  
Depressive Disorders ◽  
Case Control ◽  
Structure And Function ◽  
Small Sample ◽  
Case Control Studies ◽  
Brain Structure And Function ◽  
Small Sample Sizes ◽  
And Function ◽  
Study Designs ◽  
And Control

Neuroimaging techniques have been used extensively to compare brain structure and function between patients with, or at risk of, depression and control subjects. The goal of this work has largely been to identify pathophysiological processes in depression. However, progress in this field has been limited by the heterogeneity of patient populations, the use of small sample sizes, and an overreliance on case-control studies. These limitations have increasingly been acknowledged with recent work collecting much larger samples and employing a variety of study designs, including those able to stratify patient populations. This chapter reviews imaging studies in depression, highlighting both outstanding questions and promising recent findings.

scholarly journals Do Case-Control Studies Always Estimate Odds Ratios?

2020 ◽  
Author(s):  
Jeremy A Labrecque ◽  
Myriam M G Hunink ◽  
M Arfan Ikram ◽  
M Kamran Ikram
Keyword(s):  
Incidence Rate ◽  
Case Control Study ◽  
Case Control ◽  
Small Sample ◽  
Incidence Density ◽  
Odds Ratios ◽  
Case Control Studies ◽  
Rate Ratios ◽  
Study Designs ◽  
Control Study

Abstract Case-control studies are an important part of the epidemiologic literature, yet confusion remains about how to interpret estimates from different case-control study designs. We demonstrate that not all case-control study designs estimate odds ratios. On the contrary, case-control studies in the literature often report odds ratios as their main parameter even when using designs that do not estimate odds ratios. Only studies using specific case-control designs should report odds ratios, whereas the case-cohort and incidence-density sampled case-control studies must report risk ratio and incidence rate ratios, respectively. This also applies to case-control studies conducted in open cohorts, which often estimate incidence rate ratios. We also demonstrate the misinterpretation of case-control study estimates in a small sample of highly cited case-control studies in general epidemiologic and medical journals. We therefore suggest that greater care be taken when considering which parameter is to be reported from a case-control study.

scholarly journals WMW-A: Rank-based two-sample independent test for small sample sizes through an auxiliary sample

2021 ◽  
Author(s):  
Yin Guo ◽  
Limin Li
Keyword(s):  
Gene Expression ◽  
Case Control ◽  
Test Methods ◽  
Small Sample ◽  
Sample Problem ◽  
Auxiliary Data ◽  
Independent Test ◽  
Small Sample Problem ◽  
Small Sample Sizes ◽  
And Control

Two-sample independent test methods are widely used in case-control studies to identify significant changes or differences, for example, to identify key pathogenic genes by comparing the gene expression levels in normal and disease cells. However, due to the high cost of data collection or labelling, many studies face the small sample problem, for which the traditional two-sample test methods often lose power. We propose a novel rank-based nonparametric test method WMW-A for small sample problem by introducing a three-sample statistic through another auxiliary sample. By combining the case, control and auxiliary samples together, we construct a three-sample WMW-A statistic based on the gap between the average ranks of the case and control samples in the combined samples. By assuming that the auxiliary sample follows a mixed distribution of the case and control populations, we analyze the theoretical properties of the WMW-A statistic and approximate the theoretical power. The extensive simulation experiments and real applications on microarray gene expression data sets show the WMW-A test could significantly improve the test power for two-sample problem with small sample sizes, by either available unlabelled auxiliary data or generated auxiliary data.

scholarly journals Preference for biological motion is reduced in ASD: implications for clinical trials and the search for biomarkers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
L. Mason ◽  
F. Shic ◽  
T. Falck-Ytter ◽  
B. Chakrabarti ◽  
T. Charman ◽  
...  
Keyword(s):  
Biological Motion ◽  
Brain Regions ◽  
Autism Spectrum ◽  
Case Control ◽  
Small Sample ◽  
Social Brain ◽  
Small Sample Sizes ◽  
Social Communicative ◽  
Perception Of Biological Motion ◽  
And Control

Abstract Background The neurocognitive mechanisms underlying autism spectrum disorder (ASD) remain unclear. Progress has been largely hampered by small sample sizes, variable age ranges and resulting inconsistent findings. There is a pressing need for large definitive studies to delineate the nature and extent of key case/control differences to direct research towards fruitful areas for future investigation. Here we focus on perception of biological motion, a promising index of social brain function which may be altered in ASD. In a large sample ranging from childhood to adulthood, we assess whether biological motion preference differs in ASD compared to neurotypical participants (NT), how differences are modulated by age and sex and whether they are associated with dimensional variation in concurrent or later symptomatology. Methods Eye-tracking data were collected from 486 6-to-30-year-old autistic (N = 282) and non-autistic control (N = 204) participants whilst they viewed 28 trials pairing biological (BM) and control (non-biological, CTRL) motion. Preference for the biological motion stimulus was calculated as (1) proportion looking time difference (BM-CTRL) and (2) peak look duration difference (BM-CTRL). Results The ASD group showed a present but weaker preference for biological motion than the NT group. The nature of the control stimulus modulated preference for biological motion in both groups. Biological motion preference did not vary with age, gender, or concurrent or prospective social communicative skill within the ASD group, although a lack of clear preference for either stimulus was associated with higher social-communicative symptoms at baseline. Limitations The paired visual preference we used may underestimate preference for a stimulus in younger and lower IQ individuals. Our ASD group had a lower average IQ by approximately seven points. 18% of our sample was not analysed for various technical and behavioural reasons. Conclusions Biological motion preference elicits small-to-medium-sized case–control effects, but individual differences do not strongly relate to core social autism associated symptomatology. We interpret this as an autistic difference (as opposed to a deficit) likely manifest in social brain regions. The extent to which this is an innate difference present from birth and central to the autistic phenotype, or the consequence of a life lived with ASD, is unclear.

Effects Of Exercise-induced Hypohydration On Brain Structure And Function, A MRI Study

2017 ◽  
Vol 49 (5S) ◽  
pp. 824 ◽  
Author(s):  
X. r. Tan ◽  
Ivan C. C. Low ◽  
Mary C. Stephenson ◽  
T. Kok ◽  
Heinrich W. Nolte ◽  
...  
Keyword(s):  
Brain Structure ◽  
Structure And Function ◽  
Brain Structure And Function ◽  
Exercise Induced ◽  
Mri Study ◽  
And Function

Effects of low-level sarin and cyclosarin exposure and Gulf War Illness on Brain Structure and Function: A study at 4T

2011 ◽  
Vol 32 (6) ◽  
pp. 814-822 ◽  
Author(s):  
Linda L. Chao ◽  
Linda Abadjian ◽  
Jennifer Hlavin ◽  
Deiter J. Meyerhoff ◽  
Michael W. Weiner
Keyword(s):  
Brain Structure ◽  
Gulf War ◽  
Structure And Function ◽  
Gulf War Illness ◽  
Low Level ◽  
Brain Structure And Function ◽  
And Function
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