Effect of smoking on Brain-Derived Neurotrophic Factor (BDNF) blood levels: A systematic review and meta-analysis

BACKGROUND

Brain-Derived Neurotrophic Factor (BDNF) is a neurotrophin that plays a crucial role in neuronal survival and plasticity. Previous studies have suggested that smoking may influence BDNF levels, but the findings have been inconsistent.

METHODS

A comprehensive search of electronic databases was conducted to identify relevant studies. Inclusion criteria were applied to select studies that investigated the relationship between smoking and blood levels of BDNF. A random-effects model was used to estimate the overall effect size.

RESULTS

A total of 23 studies were included. The meta-analysis revealed a significant association between smoking and increased blood levels of BDNF (standardized mean difference [SMD] = -0.38, 95 % confidence interval [CI] 0.15 to 0.62, p = 0.002). Subgroup analyses based on BDNF source showed a significant increase in plasma-derived BDNF levels (SMD = 1.02, 95 % CI 0.50 to 1.53, p = 0.0001), while no significant difference was observed in serum-derived BDNF levels (SMD = 0.02, 95 % CI -0.19 to 0.22, p = 0.87). The pooled analysis revealed a non-significant difference in blood levels of BDNF between former smokers and non-smokers (random-effects model, SMD = 0.21, 95 % CI -0.04 to 0.46, p = 0.1).

CONCLUSION

Smokers exhibited significantly higher plasma levels of BDNF compared to non-smokers. Further research is needed to elucidate the underlying mechanisms and explore the potential therapeutic implications of targeting BDNF in smoking.

Brain-derived neurotrophic factor (BDNF) as a potential marker of endometriosis: a systematic review and meta-analysis

BACKGROUND

The existing literature on the association between BDNF protein levels and endometriosis presents inconsistent findings. This systematic review and meta-analysis aim to synthesize the available evidence and evaluate the possible relationship between BDNF protein levels and endometriosis.

METHODS

Electronic databases (PubMed, Embase, Scopus, PsycINFO, and Web of Science) were used to conduct a comprehensive literature search from inception to June 2023. The search strategy included relevant keywords and medical subject headings (MeSH) terms related to BDNF, endometriosis, and protein levels. A random-effects model was used for the meta-analysis, and to explore heterogeneity subgroup analyses were performed. funnel plots and statistical tests were used for assessing the publication bias.

RESULTS

A total of 12 studies were included. The pooled standardized mean difference (SMD) of BDNF levels between women with endometriosis and controls was 0.87 (95% confidence interval [CI] 0.34 to 1.39, p = 0.001; I2 = 93%). The results showed that blood levels of BDNF are significantly higher in endometriosis patients (SMD: 1.13 95% CI 0.54 to 1.73, p = 0.0002; I2 = 93%). No significant publication bias was observed based on the results of Egger's regression test ((p = 0.15).

CONCLUSION

This study revealed a significant difference between patients diagnosed with endometriosis and healthy control in the level of BDNF. The results indicate that women with endometriosis have higher levels of BDNF. Further studies are needed to be undertaken to investigate the role of BDNF in endometriosis pathophysiology and the diagnostic value of BDNF in endometriosis.

Brain-derived neurotrophic factor (BDNF) levels in panic disorder: A systematic review and meta-analysis

BACKGROUND

The existing literature on the association between brain-derived neurotrophic factor (BDNF) protein levels and panic disorder presents inconsistent findings. This systematic review and meta-analysis aim to synthesize the available evidence and determine the overall effect of BDNF protein levels in individuals diagnosed with panic disorder.

METHODS

A comprehensive literature search was conducted using electronic databases (PubMed, Embase, Scopus, PsycINFO, and Web of Science) from inception to April 21, 2023. The search strategy included relevant keywords and medical subject headings terms related to BDNF, panic disorder, and protein levels. A random-effects model was used for the meta-analysis, and subgroup analyses were performed to explore heterogeneity. Publication bias was assessed using funnel plots and statistical tests.

RESULTS

A total of 12 studies met the inclusion criteria. The meta-analysis demonstrated a significant decrease in BDNF protein levels in individuals with panic disorder (SMD = -.53, 95% CI: -1.02 to -.04, p < .001; I2 : 92%). The results of subgroup and meta-regression analyses were not statistically significant. No significant publication bias was observed based on the results of Egger's regression test (p-value = .3550).

CONCLUSION

This systematic review and meta-analysis provide evidence of lower BDNF protein levels in individuals diagnosed with panic disorder compared to healthy controls. The findings suggest a potential role for BDNF dysregulation in the pathophysiology of panic disorder. Further research is warranted to elucidate the underlying mechanisms and potential therapeutic implications.

Frailty as a predictor of adverse outcomes in burn patients: a systematic review

BACKGROUND

The identification of new prognostic tools for the prediction of burn patients' morbidity outcomes is necessary. Considering the feasibility of frailty assessment in the clinical setting, we aim to systematically review the literature on the associations between frailty and adverse outcomes in burn patients.

METHODS

Studies were retrieved from MEDLINE (through PubMed), Web of Science, Scopus, and Embase from their inception up to 8 September 2022. Included studies were those that used frailty indices to predict adverse outcomes in burn patients. The quality assessment was done using the National, Heart, Lung, and Blood Institute (NHLBI) checklist. The results were synthesized narratively.

RESULTS

We included 18 studies. The sample size among the included studies varied between 42-1615 patients. There were 12 research articles and 6 conference abstracts. Most of the studies were recently published in 2021 and 2022. Seven different frailty measures were evaluated. The following frailty measures were used: Canadian Study for Health and Ageing (CSHA) Clinical Frailty score (CFS), Modified frailty index-11 (mFI-11), Hospital frailty index, FRAIL scale, Emergency General Surgery Frailty Index (EGSFI), and Burn frailty index (BFI). There was only one report regarding a specific frailty index designed for the burn population (BFI). Except for one study (which used mFI-11), all included studies have shown a significant effect between assessing frailty and predicting worse outcomes. The CFS was an independent predictor of mortality among the burn population with high certainty of evidence. We found a significant association for other frailty indices as a predictor of mortality, however, the certainty of evidence regarding those was not high. Eight studies found a positive association between assessing frailty and unfavorable discharge location. There was no association between frailty and increased length of stay.

CONCLUSION

In conclusion, the postadmission assessment of frailty can be a reliable tool for predicting unfavorable outcomes and mortalities among patients with burn injuries. In addition, future studies with various populations from other countries are required to evaluate the efficacy of frailty indices measurement in order to strengthen the available evidence.

Sleep disturbance increases the risk of severity and acquisition of COVID-19: a systematic review and meta-analysis

BACKGROUND

Understanding the association between sleep quality and COVID-19 outcomes is crucial for effective preventive strategies and patient management. This systematic review aims to evaluate the impact of sleep quality as a risk factor for acquiring COVID-19 infection and the severity of the disease.

METHODS

A comprehensive search of electronic databases was conducted to identify relevant studies published from the inception of the COVID-19 pandemic which was 31st of December 2019 until 30 April 2023. Studies investigating the relationship between sleep quality and COVID-19 infection, or disease severity were included. Random effect meta-analysis was performed with odds ratios (OR) and their 95% confidence intervals (95% CI) as effect measures.

RESULTS

Out of the initial 1,132 articles identified, 12 studies met the inclusion criteria. All studies were observational studies (cohort, case-control, and cross-sectional). The association between sleep quality and COVID-19 infection risk was examined in 6 studies, The results of our meta-analysis showed that participants with poor sleep quality showed a 16% increase regarding the risk of COVID-19 acquisition (OR 1.16; 95% CI 1.03, 1.32; I2 = 65.2%, p = 0.02). Our results showed that participants with poor sleep quality showed a 51% increase in the incidence of primary composite outcome (OR 1.51; 95% CI 1.25, 1.81; I2 = 57.85%, p < 0.001). The result of our subgroup analysis also showed significantly increased risk of mortality (RR 0.67; 95% CI 0.50, 0.90; I2 = 31%, p = 0.008), and disease severity (OR 1.47; 95% CI 1.19, 1.80; I2 = 3.21%, p < 0.001) when comparing poor sleep group to those with good sleep quality.

CONCLUSION

This study highlights a significant association between poor sleep quality and an increased risk of COVID-19 infection as well as worse disease clinical outcomes.

Trends in Prevalent Injuries among Iranian Pilgrims in Hajj

BACKGROUND

Annually millions of Muslims depart to Saudi Arabia for performing a religious pilgrimage called "Hajj". In this ceremony, pilgrims face numerous health hazards and injuries such as pressing in overcrowding, sliding, burning, falling down, traffic accidents etc. The main purpose of this study was to determine the prevalence of injuries in Hajj period across 2004 to 2008.

METHODS

This study was conducted on 253808 Iranian pilgrims on five consecutive years of Hajj ceremonies, from 2004 to 2008. We used a report sheet with 13 types of injuries and 13 mechanisms of these injuries. SPSS V13.5 soft ware was used for analyzing the data. ANOVA and independent sample t - test was conducted, and relationships were considered significant at P< 0.05.

RESULTS

The most common injuries was "tissue contusions and ruptures "(about 76/10000), and "tendon lesions" (about 62/10000). In addition, the most common mechanism of injuries was "ankle sprain" (69/10000) during the five consecutive years. The prevalence of all fractures was about 49/10000 and the proportion of burning with hot water or fire was about 40/10000. Changes of all causes of the injuries were significant in this study (P< 0.05).

CONCLUSIONS

We have suggested some directions for preventing of injuries and related Injuries in Hajj, in this study.