Brain structural and functional abnormalities in mood disorders: implications for neurocircuitry models of depression

Incidence and relative risk of delirium after major surgery for patients with pre-operative depression: a systematic review and meta-analysis

BACKGROUND

Delirium is a common and potentially serious complication after major surgery. A previous history of depression is a known risk factor for experiencing delirium in patients admitted to the hospital, but the generalised risk has not been estimated in surgical patients.

METHODS

We conducted a systematic review and meta-analysis of studies reporting the incidence or relative risk (or relative odds) of delirium in the immediate postoperative period for adults with pre-operative depression. We included studies that defined depression as either a formal pre-existing diagnosis or having clinically important depressive symptoms measured using a patient-reported instrument before surgery. Multilevel random effects meta-analyses were used to estimate the pooled incidences and pooled relative risks. We also conducted subgroup analyses by various study-level characteristics to identify important moderators of pooled estimates.

RESULTS

Forty-two studies (n = 4,664,051) from five continents were included. The pooled incidence of postoperative delirium for patients with pre-operative depression was 29% (95%CI 17-43%, I2 = 99.0%), compared with 15% (95%CI 6-28%, I2 = 99.8%) in patients without pre-operative depression and 21% (95% CI 11-33%, I2 = 99.8%) in the cohorts overall. For patients with pre-operative depression, the risk of delirium was 1.91 times greater (95%CI 1.68-2.17, I2 = 42.0%) compared with patients without pre-operative depression.

CONCLUSIONS

Patients with a previous diagnosis of depression or clinically important depressive symptoms before surgery have substantially greater risk of experiencing delirium after surgery. Clinicians and patients should be informed of these increased risks. Robust screening and other risk mitigation strategies for postoperative delirium are warranted, especially for patients with pre-operative depression.

Risk of Parkinson's disease and depression severity in different populations: A two-sample Mendelian randomization analysis

BACKGROUND

Depression is widely recognized as a common non-motor symptom of Parkinson's disease (PD). Across different studies, the reported prevalence of depression in PD varies widely, ranging from 2.7% to 90%, but it is unclear whether this association is due to genetic or acquired factors. Whether there is a causal relationship remains unknown. The aim of this study was to use a two-sample Mendelian randomization (MR) approach to investigate the causal effect of PD on depression.

METHODS

Analyses were conducted separately for individuals of European and East Asian ancestry using publicly available summary data from genome-wide association studies. Depression was divided into two categories: ever depressed for a whole week and major depressive disorder (MDD). PD data were used as the exposure and were obtained from the International Parkinson's Disease Genomics Consortium and the BioBank Japan PheWeb, while depression data were used as the outcome and were obtained from the ntegrative Epidemiology Unit (IEU) Open GWAS Project(A public GWAS database） and the Psychiatric Genomics Consortium. The influence of PD on depression was assessed using inverse variance weighted (IVW), weighted median, MR-Egger, and weighted mode methods. Heterogeneity and pleiotropy were tested, and the results were validated using FinnGen GWAS data from version R9.

RESULTS

In individuals of European ancestry, there was a causal relationship between PD and ever depressed for a whole week (IVW method, odds ratio [OR] = 0.990; 95% CI, 0.984-0.996; p = .002), but no causal relationship was observed between PD and MDD (IVW method, OR = 0.974; 95% CI, 0.942-1.009; p = .141). In individuals of East Asian ancestry, no causal relationship was observed between PD and ever depressed for a whole week (IVW method, OR = 1.001; 95% CI, 0.829-1.209; p = .990) and between PD and MDD (IVW method, OR = 1.017; 95% CI, 0.982-1.052; p = .342). The results of the three additional analysis methods were similar to those of the IVW method, and there was no heterogeneity according to Cochran's Q-test. There was no evidence of pleiotropy based on MR-Egger intercept test and MR-PRESSO. The FinnGen validation dataset supported these findings. The results are stable and reliable.

CONCLUSION

The observed increase in depression among PD patients could potentially be attributed to modifiable acquired factors. Consequently, there is an urgent need to strengthen the management of PD patients in order to prevent the development of depression in the future.

Potential correlations between abnormal homogeneity of default mode network and personality or lipid level in major depressive disorder

BACKGROUND

Default mode network (DMN) is one of the most recognized resting-state networks in major depressive disorder (MDD). However, the homogeneity of this network in MDD remains incompletely explored. Therefore, this study aims to determine whether there is abnormal network homogeneity (NH) of the DMN in MDD patients. At the same time, correlations between clinical variables and brain functional connectivity are examined.

METHODS

We enrolled 42 patients diagnosed with MDD and 42 HCs. A variety of clinical variables were collected, and data analysis was conducted using the NH and independent component analysis methods.

RESULTS

The study shows that MDD patients have higher NH values in the left superior medial prefrontal cortex (MPFC) and left posterior cingulate cortex (PCC) compared to HCs. Additionally, there is a positive correlation between NH values of the left superior MPFC and Eysenck Personality Questionnaire values. NH values of the left PCC are positively linked to CHOL levels, LDL levels, and utilization scores. However, these correlations lose significance after the Bonferroni correction.

CONCLUSION

Our findings indicate the presence of abnormal DMN homogeneity in MDD, underscoring the significance of DMN in the pathophysiology of MDD. Simultaneously, the study provides preliminary evidence for the correlation between clinical variables and brain functional connectivity.

Smartphone app for lifestyle improvement improves brain health and boosts the vitality and cognitive function of healthy middle-aged adults

INTRODUCTION

The number of smartphone apps for brain training is increasing, and the number of people who are working on brain training is also increasing. However, researchers disagree about the effectiveness of brain training.

METHODS

Therefore, in this study, we conducted an intervention test with the participation of 70 healthy middle-aged men and women and measured the effect of smartphone apps on lifestyle improvement using brain healthcare quotient calculated from brain imaging data.

RESULTS

As a result, in the intervention group, significant improvements were seen in fractional anisotropy (FA) of the whole brain, corpus callosum, internal capsule, corona radiata, posterior thalamic radiation, external capsule, and superior longitudinal fasciculus. Additionally, in the intervention group, these FA increments correlated with improvements in cognitive function as measured by the trail-making test and vigor as measured by the Profile of Mood States 2nd Edition.

CONCLUSION

The results of this study suggest that improving lifestyle habits through smartphone apps can improve brain health and cognitive and emotional performance of healthy middle-aged adults. This is consistent with previous research that suggests that FA integrity in the limbic-thalamo-cortical pathway influences cognitive function and emotion regulation.