Demographic and Clinical Characteristics of Completed Suicides in Mexico City 2014-2015

Proteome analysis of the prefrontal cortex and the application of machine learning models for the identification of potential biomarkers related to suicide

Introduction

Suicide is a significant public health problem, with increased rates in low- and middle-income countries such as Mexico; therefore, suicide prevention is important. Suicide is a complex and multifactorial phenomenon in which biological and social factors are involved. Several studies on the biological mechanisms of suicide have analyzed the proteome of the dorsolateral prefrontal cortex (DLPFC) in people who have died by suicide. The aim of this work was to analyze the protein expression profile in the DLPFC of individuals who died by suicide in comparison to age-matched controls in order to gain information on the molecular basis in the brain of these individuals and the selection of potential biomarkers for the identification of individuals at risk of suicide. In addition, this information was analyzed using machine learning (ML) algorithms to propose a model for predicting suicide.

Methods

Brain tissue (Brodmann area 9) was sampled from male cases (n=9) and age-matched controls (n=7). We analyzed the proteomic differences between the groups using two-dimensional polyacrylamide gel electrophoresis and mass spectrometry. Bioinformatics tools were used to clarify the biological relevance of the differentially expressed proteins. In addition, this information was analyzed using machine learning (ML) algorithms to propose a model for predicting suicide.

Results

Twelve differentially expressed proteins were also identified (t 14 ≤ 0.5). Using Western blotting, we validated the decrease in expression of peroxiredoxin 2 and alpha-internexin in the suicide cases. ML models were trained using densitometry data from the 2D gel images of each selected protein and the models could differentiate between both groups (control and suicide cases).

Discussion

Our exploratory pathway analysis highlighted oxidative stress responses and neurodevelopmental pathways as key processes perturbed in the DLPFC of suicides. Regarding ML models, KNeighborsClassifier was the best predicting conditions. Here we show that these proteins of the DLPFC may help to identify brain processes associated with suicide and they could be validated as potential biomarkers of this outcome.

Dysregulated zinc homeostasis and microadenomas in the anterior pituitary: pathological insights into suicide risk

Background

Suicide is a significant public health problem influenced by various risk factors, including dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis. Zinc (Zn), essential for pituitary function in hormone synthesis and release, has been linked to suicide, with studies noting reduced serum levels and altered brain transport mechanisms. Despite Zn's crucial role in pituitary function and its involvement in suicidal behavior, information on pituitary Zn in suicide is scarce. Tumor cells modify Zn dynamics in tissues, and a previous report suggests microadenomas in the anterior pituitary as a risk factor for suicide.

Methods

Histopathological analysis with hematoxylin-eosin stain and histochemical techniques to assess Zn homeostasis were carried out on anterior pituitary postmortem samples from 14 suicide completers and 9 non-suicidal cases.

Results

Pituitary microadenomas were identified in 35% of suicide cases and none in the non-suicidal cases. Furthermore, compartmentalized Zn (detected via dithizone reactivity), but not free Zn levels (detected via zinquin reactivity), was lower in the suicide cases compared to the non-suicidal group.

Conclusion

This is the first report of a potential association between disrupted Zn homeostasis and microadenomas in the anterior pituitary as a feature in suicide and provides critical insights for future neuroendocrine Zn-related research.

Association of Medicaid coverage with emergency department utilization after self-harm in Korea: A nationwide registry-based study

BACKGROUND

Self-harm presents an important public health challenge. It imposes a notable burden on the utilization of emergency department (ED) services and medical expenses from patients and family. The Medicaid system is vital in providing financial support for individuals who struggle with medical expenses. This study explored the association of Medicaid coverage with ED visits following incidents of self-harm, utilizing nationwide ED surveillance data in Korea.

METHODS

Data of all patients older than 14 years who presented to EDs following incidents of self-harm irrespective of intention to end their life, including cases of self-poisoning, were gathered from the National ED Information System (NEDIS). The annual self-harm visit rate (SHVR) per 100,000 people was calculated for each province and a generalized linear model analysis was conducted, with SHVR as a dependent variable and factors related to Medicaid coverage as independent variables.

RESULTS

A 1% increase in Medicaid enrollment rate was linked to a significant decrease of 14% in SHVR. Each additional 1,000 Korean Won of Medicaid spending per enrollee was correlated with a 1% reduction in SHVR. However, an increase in Medicaid visits per enrollee and an extension of Medicaid coverage days were associated with an increase in SHVR. SHVR exhibited a stronger associated with parameters of Medicaid coverage in adolescents and young adults than in older adult population.

CONCLUSION

Expansion of Medicaid coverage coupled with careful monitoring of shifts in Medicaid utilization patterns can mitigate ED overloading by reducing visits related to self-harm.

Suicide Attempt Violence: Gender Differences, Diagnosis and Psychiatric Care Seeking in Mexico City

BACKGROUND

Suicide cases in Mexico have increased during the last two years and are the second-leading cause of death in the young adult population.

AIM

To describe gender differences in violent suicide attempts as relates to diagnosis and the seeking of psychiatric care.

METHODS

A descriptive retrospective study was conducted. The referral forms of 241 patients who had attempted suicide were analyzed.

RESULTS

The mean age of the patients was 29.1 (SD=10.8) years, n=140 (58.1%) of the sample were women. Affective disorders were the most frequent diagnoses for both sexes. Women were more likely to delay seeking psychiatric care: 60 days versus 30 days of delay for men (p=0.009). Men were shown to more frequently resort to violent suicide methods. Both women and men who used violent suicide methods were shown to delay by more days the seeking of psychiatric care than those who were found to have used non-violent suicide methods.

CONCLUSION

We found that patients who use more violent methods of suicide took longer before seeking psychiatric care. This delay in accessing psychiatric care can be thought to contribute to the fact that completed suicides are more frequent within that category of patients. The majority of suicide attempts occurred in the 17-24 years age group; therefore, it seems reasonable to analyze the existing barriers to seeking psychiatric care, mainly in the young adult population, and to design strategies to bring mental health services closer to this population group.

Impact of the lockdown by the COVID-19 pandemic on suicidal trend in the Colombian Coffee Region

Suicide is considered a Public Health issue. In 2019 the Colombian suicide rate was 5.8 per-100.000 inhabitant. Likewise, the Colombian Coffee Region has doubled the national average on these rates. On the other hand, the Pandemic COVID 19 socio-economic consequences are aggravating the risk factors that we've known about suicide.

Objective

To evaluate the suicidal trend in the population of the Colombian Coffee Region during the COVID-19 pandemic and compare it with a non-pandemic period.

Methods

The data were taken from the National Institute of Legal Medicine and Forensic Science for the suicidal events during the 2016-2020 period in the Colombian Coffee Region, and the Montecarlo Regression was applied using the JoinPoint Regression Program.

Results

We found 1022 cases, most of them were men. The mean age was 34 years. The most used method was hanging in both sexes. Half of them had at least a high school degree. Half of the suicides were committed by single people. One-third of the cases had a previous mental illness. There are significant differences in the suicidal trend between the lockdown period and the non-lockdown period with a P value < 0.05.

Conclusions

We found most suicidal cases between older men and an inversely proportional relationship between education and suicidal rate. Is interesting that the most applied method for suicide for both sexes was hanging. The suicidal trend was increasing until 2020, although in the lockdown we found a decrease. In the post-lockdown period for men was a posterior increase and for women the trend has a continued decrease.

Increased suicide rates in Mexico City during the COVID-19 pandemic outbreak: An analysis spanning from 2016 to 2021

Objective

Coronavirus disease 2019 (COVID-19) has impacted mental health worldwide, and suicide can be a serious outcome of this. Thus, suicide characteristics were examined before and during the COVID-19 pandemic in Mexico City.

Methods

This is a retrospective study including all Mexico City residents who had a coroner's record with a cause of death of intentional self-harm (ICD-10) from January 2016 to December 2021.

Results

From 2016 to 2021, 3636 people committed suicide, of which 2869 were males (78.9%) and 767 females (21.1%). From 2016 to 2019 the suicide rate remained constant (∼6 per 100000) and dramatically increased in 2020 (10.45 per 100,000), to return to the levels of the previous year in 2021 (6.95 per 100000). The suicide rate in 2020 specifically increased from January to June (COVID-19 outbreak) in all age groups. Moreover, every year young people (15-24 years) have the maximum suicide rate and depression was the main suicide etiology.

Conclusion

The COVID-19 pandemic outbreak increased the suicide rate, regardless of age, but suicide prevalence was higher in males and young people, regardless of the COVID-19 pandemic. These findings confirm that suicide is a complex and multifactorial problem and will allow the establishment of new guidelines for prevention and care strategies.

Gender Differences in Suicide and Homicide Rates in Mexico City during 2019

Suicides and homicides are public health problems around the world. The rates of suicide and homicide have increased in the past years. The objectives of this study are to estimate the rates of suicide and homicide in Mexico City, and to determine the rates of suicide and homicide by sex in the different municipalities of Mexico City during 2019. Data analyzed were obtained from files of governmental organizations in Mexico City. From the general victims-in-research-folders, we choose “victims of crime” or “loss of life by suicide” that happened in 2019. Sex and municipality of residence were obtained. The rate of suicide was of 5.65 cases per 100,000 habitants. Stratified by gender and by municipalities, the highest rates observed were 6.8 suicides per 100,000 males and 29.6 suicides per 100,000 females. The sex ratio was 4.2:1 (males: females). Regarding homicides, the rates were 16.68 homicides per 100,000 females and 67.41 homicides per 100,000 males. The Venustiano Carranza Municipality showed the highest homicide rate in men with 131.72 homicides per 100,000 males. The homicide sex ratio was 7.8:1. The findings of the present study highlight that death by suicide is more common in men with 7.8 more times than in women. The municipalities with higher deaths by suicide have lower rates of homicides and the municipalities with higher deaths by suicide showed lower rates of suicide in men.

Metals, Nanoparticles, Particulate Matter, and Cognitive Decline

Exposure to metals is ubiquitous and emission sources include gasoline, diesel, smoke from wildfires, contaminated soil, water and food, medical implants, waste recycling facilities, subway exposures, and occupational environments. PM_2.5 exposure is associated with impaired cognitive performance, neurobehavioral alterations, incidence of dementia, and Alzheimer's disease (AD) risk. Heavy-duty diesel vehicles are major emitters of metal-rich PM_2.5 and nanoparticles in Metropolitan Mexico City (MMC). Cognitive impairment was investigated in 336 clinically healthy, middle-class, Mexican volunteers, age 29.2 ± 13.3 years with 13.7 ± 2.4 years of education using the Montreal Cognitive Assessment (MoCA). MoCA scores varied with age and residency in three Mexican cities with cognition deficits impacting ~74% of the young middle-class population (MoCA ≤ 25). MMC residents ≥31 years (x¯46.2 ± 11.8 y) had MoCA x¯20.4 ± 3.4 vs. low pollution controls 25.2 ± 2.4 (p < 0.0001). Formal education years positively impacted MoCA total scores across all participants (p < 0.0001). Residency in PM_2.5 polluted cities impacts multi-domain cognitive performance. Identifying and making every effort to lower key pollutants impacting neural risk trajectories and monitoring cognitive longitudinal performance are urgent. PM_2.5 emission control should be prioritized, metal emissions targeted, and neuroprevention interventions implemented early.

Integrative DNA Methylation and Gene Expression Analysis in the Prefrontal Cortex of Mexicans Who Died by Suicide

BACKGROUND

Suicide represents a major health concern, especially in developing countries. While many demographic risk factors have been proposed, the underlying molecular pathology of suicide remains poorly understood. A body of evidence suggests that aberrant DNA methylation and expression is involved. In this study, we examined DNA methylation profiles and concordant gene expression changes in the prefrontal cortex of Mexicans who died by suicide.

METHODS

In collaboration with the coroner's office in Mexico City, brain samples of males who died by suicide (n = 35) and age-matched sudden death controls (n = 13) were collected. DNA and RNA were extracted from prefrontal cortex tissue and analyzed with the Infinium Methylation480k and the HumanHT-12 v4 Expression Beadchips, respectively.

RESULTS

We report evidence of altered DNA methylation profiles at 4430 genomic regions together with 622 genes characterized by differential expression in cases vs controls. Seventy genes were found to have concordant methylation and expression changes. Metacore-enriched analysis identified 10 genes with biological relevance to psychiatric phenotypes and suicide (ADCY9, CRH, NFATC4, ABCC8, HMGA1, KAT2A, EPHA2, TRRAP, CD22, and CBLN1) and highlighted the association that ADCY9 has with various pathways, including signal transduction regulated by the cAMP-responsive element modulator, neurophysiological process regulated by the corticotrophin-releasing hormone, and synaptic plasticity. We therefore went on to validate the observed hypomethylation of ADCY9 in cases vs control through targeted bisulfite sequencing.

CONCLUSION

Our study represents the first, to our knowledge, analysis of DNA methylation and gene expression associated with suicide in a Mexican population using postmortem brain, providing novel insights for convergent molecular alterations associated with suicide.

Environmental Nanoparticles, SARS-CoV-2 Brain Involvement, and Potential Acceleration of Alzheimer's and Parkinson's Diseases in Young Urbanites Exposed to Air Pollution

Alzheimer's and Parkinson's diseases (AD, PD) have a pediatric and young adult onset in Metropolitan Mexico City (MMC). The SARS-CoV-2 neurotropic RNA virus is triggering neurological complications and deep concern regarding acceleration of neuroinflammatory and neurodegenerative processes already in progress. This review, based on our MMC experience, will discuss two major issues: 1) why residents chronically exposed to air pollution are likely to be more susceptible to SARS-CoV-2 systemic and brain effects and 2) why young people with AD and PD already in progress will accelerate neurodegenerative processes. Secondary mental consequences of social distancing and isolation, fear, financial insecurity, violence, poor health support, and lack of understanding of the complex crisis are expected in MMC residents infected or free of SARS-CoV-2. MMC residents with pre-SARS-CoV-2 accumulation of misfolded proteins diagnostic of AD and PD and metal-rich, magnetic nanoparticles damaging key neural organelles are an ideal host for neurotropic SARS-CoV-2 RNA virus invading the body through the same portals damaged by nanoparticles: nasal olfactory epithelium, the gastrointestinal tract, and the alveolar-capillary portal. We urgently need MMC multicenter retrospective-prospective neurological and psychiatric population follow-up and intervention strategies in place in case of acceleration of neurodegenerative processes, increased risk of suicide, and mental disease worsening. Identification of vulnerable populations and continuous effort to lower air pollution ought to be critical steps.

Sex differences in brain gene expression among suicide completers

BACKGROUND

Suicide rates vary substantially by sex. Suicides committed by males significantly outnumber female suicides. Disparities in community and social factors provide a partial explanation for this phenomenon. Thus, the evaluation of sex differences at a biological level might contribute to the elucidation of the factors involved in this imbalance. The aim of the present study was to evaluate sex-specific gene expression patterns in the suicidal brain.

METHODS

postmortem samples from the dorsolateral prefrontal cortex (DLPFC) of 75 Latino individuals were analyzed. We considered the following groups: i) male suicides (n = 38), ii) female suicides (n = 10), iii) male controls (n = 20), and iv) female controls (n = 7). Gene expression profiles were evaluated by microarrays. Differentially expressed genes among the groups were identified with a linear model. Similarities and differences in the gene sets between the sexes were identified.

RESULTS

Differentially expressed genes were identified between suicides and controls of each sex: 1,729 genes in females and 1,997 genes in males. Female-exclusive suicide genes were related to cell proliferation and immune response. Meanwhile, male-exclusive suicide genes were associated to DNA binding and ribonucleic protein complex. Sex-independent suicide genes showed enrichment in mitochondrial and vesicular functions.

LIMITATIONS

Relatively small sample size. Our diagnosis approach was limited to information found on coroner's records. The analysis was limited to a single brain area (DLPFC) and we used microarrays.

CONCLUSION

Previously unexplored sex differences in the brain gene expression of suicide completers were identified, providing valuable foundation for the evaluation of sex-specific factors in suicide.

Brain Gene Expression Profiling of Individuals With Dual Diagnosis Who Died by Suicide

Objective: Dual diagnosis (DD) is the co-occurrence of at least one substance use disorder and one or more mental disorders in a given individual. Despite this comorbidity being highly prevalent and associated with adverse clinical outcomes, its neurobiology remains unclear. Furthermore, patients with DD are at higher risk for suicidal behavior in comparison with single disorder patients. Our objective was to evaluate brain gene expression patterns in individuals with DD who died by suicide. Methods: We compared the gene expression profile in the dorsolateral prefrontal cortex of suicides with DD (n = 10) to the transcriptome of suicides with substance use disorder alone (n = 10), suicides with mood disorders (MD) alone (n = 13), and suicides without mental comorbidities (n = 5). Gene expression profiles were assessed by microarrays. In addition, we performed a brain cell type enrichment to evaluate whether the gene expression profiles could reflect differences in cell type compositions among the groups. Results: When comparing the transcriptome of suicides with DD to suicides with substance use disorder alone and suicides with MD alone, we identified 255 and 172 differentially expressed genes (DEG), respectively. The overlap of DEG between both comparisons (112 genes) highlighted the presence of common disrupted pathways in substance use disorder and MD. When comparing suicides with DD to suicides without mental comorbidities, we identified 330 DEG, mainly enriched in neurogenesis. Cell type enrichment indicated higher levels of glial markers in suicides with DD compared to the other groups. Conclusions: Suicides with DD exhibited a gene expression profile distinct from that of suicides with a single disorder, being substance use disorder or MD, and suicides without mental disorders. Our results suggest alteration in the expression of genes involved in glial specific markers, glutamatergic and GABAergic neurotransmission in suicides with DD compared to suicides with a single disorder and suicides without mental comorbidities. Alterations in the expression of synaptic genes at different levels were found in substance use disorder and MD.

Alzheimer disease starts in childhood in polluted Metropolitan Mexico City. A major health crisis in progress

Exposures to fine particulate matter (PM_2.5) and ozone (O₃) above USEPA standards are associated with Alzheimer's disease (AD) risk. Metropolitan Mexico City (MMC) youth have life time exposures to PM_2.5 and O₃ above standards. We focused on MMC residents ≤30 years and reviewed 134 consecutive autopsies of subjects age 20.03 ± 6.38 y (range 11 months to 30 y), the staging of Htau and ß amyloid, the lifetime cumulative PM_2.5 (CPM _2.5) and the impact of the Apolipoprotein E (APOE) 4 allele, the most prevalent genetic risk for AD. We also reviewed the results of the Montreal Cognitive Assessment (MoCA) and the brainstem auditory evoked potentials (BAEPs) in clinically healthy young cohorts. Mobile sources, particularly from non-regulated diesel vehicles dominate the MMC pollutant emissions exposing the population to PM_2.5 concentrations above WHO and EPA standards. Iron-rich,magnetic, highly oxidative, combustion and friction-derived nanoparticles (CFDNPs) are measured in the brain of every MMC resident. Progressive development of Alzheimer starts in childhood and in 99.25% of 134 consecutive autopsies ≤30 years we can stage the disease and its progression; 66% of ≤30 years urbanites have cognitive impairment and involvement of the brainstem is reflected by auditory central dysfunction in every subject studied. The average age for dementia using MoCA is 20.6 ± 3.4 y. APOE4 vs 3 carriers have 1.26 higher odds of committing suicide. PM_2.5 and CFDNPs play a key role in the development of neuroinflammation and neurodegeneration in young urbanites. A serious health crisis is in progress with social, educational, judicial, economic and overall negative health impact for 25 million residents. Understanding the neural circuitry associated with the earliest cognitive and behavioral manifestations of AD is needed. Air pollution control should be prioritised-including the regulation of diesel vehicles- and the first two decades of life ought to be targeted for neuroprotective interventions. Defining paediatric environmental, nutritional, metabolic and genetic risk factor interactions is a multidisciplinary task of paramount importance to prevent Alzheimer's disease. Current and future generations are at risk.

Genome-wide association study of suicide attempt in a Mexican population: a study protocol

INTRODUCTION

Suicidality is a complex behaviour and a major health problem; the specific features that could predispose to suicidal behaviour have been extensively investigated, most frequently in European and Asian populations. Therefore, our aim is to present a protocol that will explore suicide attempt in Mexican individuals diagnosed with psychiatric disorders, through a genome-wide association study (GWAS).

METHOD AND ANALYSIS

We will perform a GWAS by comparing 700 individuals who have suicide attempt history, with control subjects without suicide attempt history (n=500). The genotyping will be conducted using the Infinium PsychArray BeadChip and quality controls will be applied to single nucleotides (SNPs) genotyped. After that, we will perform the imputation using reference panels provided by the Haplotype Reference Consortium. We will perform two different workflows: (A) the classic GWAS analysis applying the same weight to all the variants and (B) an algorithm with prediction of deleteriousness of variants.

ETHICS AND DISSEMINATION

This study was approved by the ethics and investigation committees of the National Institute of Genomic Medicine on 22 July 2015, No CEI 215/13. We plan to disseminate research findings in scientific conferences and as a manuscript in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

CEI 215/13.

Brain Gene Expression Pattern of Subjects with Completed Suicide and Comorbid Substance Use Disorder

Background/Aim

Although individuals with substance use disorder (SUD) are at high risk of committing suicide, most studies of postmortem gene expression exclude subjects with SUD due to the potential confounding effect of drugs in the transcriptome. Thus, little is known about the gene expression profile in suicides with SUD. The identification of altered biological processes in suicides with SUD is crucial in the comprehension of the interaction between both pathologies.

Methods

We evaluated the gene expression profile in the dorsolateral prefrontal area of suicides and nonsuicides with and without SUD by microarrays.

Results

We identified 222 differentially expressed genes, predominately enriched in cell proliferation in the comparison between suicides with and without SUD. When comparing the transcriptome of suicides with SUD to nonsuicides with SUD, we identified 550 differentially expressed genes, mainly enriched in oxidative phosphorylation. Differentially expressed genes (1,417) between suicides and nonsuicides without SUD were detected. Most of them were related to mitochondrial function.

Conclusion

Interaction between suicide and SUD seems to influence the expression of genes involved in glial proliferation and glutamatergic neurotransmission. These results highlight, for the first time, that suicides with SUD have a gene expression profile distinct from that of subjects with only one of these disorders.