Childhood trauma and substance use underlying psychosis: a systematic review

Dysregulation of MiRNAs in schizophrenia in an Egyptian patient population

Schizophrenia (SZ) is a complex neuropsychiatric disorder influenced by genetic, environmental, and epigenetic factors, including miRNA dysregulation. This study explored the diagnostic and therapeutic potential of miRNAs in SZ, focusing on seven key miRNAs: miR-137-3p, miR-34a-5p, miR-432-5p, miR-130b-3p, miR-346, miR-195-5p, and miR-103a-3p. Results revealed significant dysregulation of miR-137-3p, miR-195-5p, miR-346, and miR-103a-3p, highlighting their relevance to SZ pathology. Upregulation of miR-137-3p correlated with enhanced cognitive performance, as evidenced by improved scores on the Wisconsin Card Sorting Test (WCST) and Trail Making Test B (TMT-B). Conversely, miR-195-5p and miR-346 were strongly associated with cognitive processing speed, while miR-103a-3p downregulation was linked to reduced conceptual flexibility. Cluster analyses demonstrated that miRNA expression levels varied significantly based on antipsychotic treatment and receptor targeting, suggesting potential regulatory effects of medication. Importantly, miRNAs were measured in PBMCs, highlighting their feasibility as non-invasive biomarkers. The study underscores the diagnostic value of miRNAs, offering a promising avenue for early detection and personalized interventions in SZ. Future research should validate these findings across diverse cohorts and investigate miRNA-based therapeutic strategies. By integrating miRNA profiling into clinical practice, this study provides a foundation for advancing precision medicine in SZ management.

Modern perspectives on psychoses: dissociation, automatism, and temporality across exogenous and endogenous dimensions

Substance use and the emergence of Novel Psychoactive Substances (NPS) present a significant public health challenge and diagnostic dilemma, particularly in the context of psychosis. The increasing availability of psychoactive substances among youth has led to a rise in Substance Use Disorders (SUDs), with profound implications for mental health. This paper explores the psychopathological distinctions between substance-induced psychoses (SIPs) and endogenous psychoses, such as schizophrenia, from a phenomenological perspective. We emphasize three key aspects: dissociation, mental automatism, and temporality, to elucidate the underlying mechanisms of these conditions. Dissociation, as a psychopathological organizer, is central to exogenous psychoses, particularly those triggered by NPS. This phenomenon leads to a fragmentation of consciousness, detachment from reality, and disintegration of identity, distinct from the spaltung observed in endogenous psychoses. The concept of mental automatism, as theorized by De Clerambault, is also explored, highlighting its role in the early stages of exogenous psychoses, where cognitive disruptions precede delusions and hallucinations. Furthermore, the temporal experience in SIPs is characterized by a disconnection from past and future, trapping individuals in an "eternal present." This contrasts with the fragmented temporality observed in schizophrenia, where patients struggle to maintain a coherent narrative of their lives. The phenomenological approach provides critical insights into the clinical differentiation between SIPs and Primary Psychotic Disorders (PPDs), emphasizing the need for targeted interventions that address the specific temporal and cognitive disruptions in substance-induced conditions. In conclusion, this paper underscores the importance of integrating phenomenological psychopathology into clinical practice, particularly in the face of the evolving landscape of substance use and psychosis. Understanding the distinct psychopathological mechanisms underlying SIPs can inform more accurate diagnoses and effective treatments, ultimately improving patient outcomes in the context of this growing public health issue.

Exposotypes in Psychotic Disorders

Psychiatry lags in adopting etiological approaches to diagnosis, prognosis, and outcome prediction compared to the rest of medicine. Etiological factors such as childhood trauma (CHT), substance use (SU), and socioeconomic status (SES) significantly affect psychotic disorder symptoms. This study applied an agnostic clustering approach to identify exposome clusters "Exposotypes (ETs)" and examine their relationship with clinical, cognitive, and functional outcomes. Using data from individuals with psychotic disorders (n=1,350), and controls (n=623), we assessed the relationship between the exposotypes and outcomes. Four exposotypes were identified: ET1 characterized by high CHT and SU; ET2, high CHT; ET3, high SU; ET4, low exposure. Compared to ET4, ET1 demonstrated higher positive and general symptoms, anxiety, depression, impulsivity, and mania; ET2 had higher anxiety, depression, and impulsivity; ET3 had better cognitive and functional outcomes with lower negative symptoms. Intracranial volume was largest in ET3, and smallest in ET2. No group differences in schizophrenia polygenic risk scores were found. The age of onset was 5 years earlier in ET1 than in ET4. These findings provide insight into the complex etiological interplay between trauma, and SU, as well as their unique effects on clinical symptoms, cognition, neurobiology, genetic risk, and functioning.

Risk Factors for Late-Onset Psychosis: A Case-Control Study

BACKGROUND AND HYPOTHESIS

The onset of schizophrenia occurs after the age of 40 in up to 20% of cases. We aim to depict risk factors for first-episode psychosis after the age of 40 by comparing late-onset psychosis (LOP) patients to healthy age-matched controls.

STUDY DESIGN

In this case-control study using electronic health records, 142 individuals aged 40-65 years with an encounter for a first episode of psychosis between 2013 and 2021 were included. Four controls (N = 568) were matched to each case on age, sex, race, and year of encounter. Potential risk factors for the primary analysis were captured via structured data and text-mining of medical notes. Conditional logistic regression models were used to assess the odds of LOP with potential risk factors.

STUDY RESULTS

After adjusting for all variables in the main analysis, odds for LOP were increased by immigration (OR 3.30, 95% CI, 1.56-6.98), depression (OR 3.58, 95% CI, 2.01-6.38), anxiety (OR 2.12, 95% CI, 1.20-3.75), cannabis use (OR 3.00, 95% CI, 1.36-6.61), alcohol use disorder (OR 5.46, 95% CI, 2.41-12.36), polysubstance use (OR 4.22, 95% CI, 1.30-13.7), severe trauma (OR 2.29, 95% CI, 1.08-4.48), and caregiver burden (OR 15.26, 95% CI, 3.85-60.48).

CONCLUSIONS

Life stressors along with the effects of substance use and other psychiatric conditions may confer some risk to the development of LOP. Replication is required in independent prospective studies. Further research is necessary to truly parse out which of these factors belong on the causal pathway.

The association between childhood trauma and tobacco smoking in patients with psychosis, unaffected siblings, and healthy controls

In patients with psychosis, rates of tobacco smoking and childhood trauma are significantly higher compared to the general population. Childhood trauma has been proposed as a risk factor for tobacco smoking. However, little is known about the relationship between childhood trauma and smoking in psychosis. In a subsample of the Genetic Risk and Outcome of Psychosis study (760 patients with psychosis, 991 unaffected siblings, and 491 healthy controls), tobacco smoking was assessed using the Composite International Diagnostic Interview and childhood trauma was measured with the Childhood Trauma Questionnaire. Logistic regression models were used to assess associations between trauma and smoking, while correcting for confounders. Positive associations were found between total trauma, abuse, and neglect, and an increased risk for smoking in patients, while correcting for age and gender (ORtrauma 1.77, 95% CI 1.30-2.42, p < 0.001; ORabuse 1.69, 95% CI 1.23-2.31, p = 0.001; ORneglect 1.48, 95% CI 1.08-2.02, p = 0.014). In controls, total trauma and abuse were positively associated with smoking, while correcting for age and gender (ORtrauma 2.40, 95% CI 1.49-3.88, p < 0.001; ORabuse 2.02, 96% CI 1.23-3.32, p = 0.006). All associations lost their significance after controlling for additional covariates and multiple testing. Findings suggest that the association between childhood trauma and tobacco smoking can be mainly explained by confounders (gender, cannabis use, and education) in patients with psychosis. These identified aspects should be acknowledged in tobacco cessation programs.

Identification of distinct clinical profiles and trajectories in individuals at high risk of developing psychosis: A latent profile analysis of the north American prodrome longitudinal study consortium-3 dataset

AIM

People at clinical high risk (CHR) for psychosis are a heterogeneous population in regard to clinical presentation and outcome. It is unclear, however, if their baseline clinical characteristics can be used to construct orthogonal subgroups that differ in their clinical trajectory to provide early identification of individuals in need of tailored interventions.

METHODS

We used latent profile analysis (LPA) to determine the number of distinct clinical profiles within the CHR population using the NAPLS-3 dataset, focusing on the clinical features incorporated in the NAPLS psychosis risk calculator (including age, unusual thought content and suspiciousness, processing speed, verbal learning and memory function, social functioning decline, life events, childhood trauma, and family history of psychosis). We then conducted a between-profile comparisons of clinical trajectories based on psychotic and depressive symptoms as well as substance use disorder (SUD) related features over time.

RESULTS

Two distinct profiles emerged. One profile, comprising approximately 25% of the sample, was significantly older, displayed better cognitive performance, experienced more types of traumatic and undesirable life events, exhibited a greater decline in functioning in the past year, and was more likely to have relatives with psychosis. This group showed worse positive symptoms and SUD-related features over time, although groups did not differ in the proportion of individuals who developed psychosis.

CONCLUSIONS

LPA results suggest CHRs can be segregated into two profiles with different clinical trajectories. Characterizing individuals within these clinical profiles may help understand the divergent outcomes of this population and ultimately facilitate the development of specialized interventions.

Adolescent Violence in the Home Among Youth Presenting to an Early Psychosis Service: An Exploration of Contributing Factors

Adolescent violence in the home is a growing public health issue and remains under reported and under-researched. The focus of the present research is to investigate factors that may contribute to adolescent violence in the home, among acohort of young people with co-occurring early psychosis. Data relates to 50 young people (16 females, 33 males, 1 nonbinary) aged from 16-25 who were clients at a youth early psychosis service in Melbourne, Australia. Results from a discriminant function analysis revealed the two major contributing factors to whether someone used violence in the home, were whether a young person had a coexisting neurodevelopmental or intellectual disability and whether they used violence outside the home. The findings provide preliminary evidence that engaging in violence outside the home and the presence of a neurodevelopmental or intellectual disability may make it more likely for young people with early psychosis to use violence in the home.

Accidental substance-related acute toxicity deaths among youth in Canada: a descriptive analysis of a national chart review study of coroner and medical examiner data

INTRODUCTION

Substance-related acute toxicity deaths (ATDs) are a public health crisis in Canada. Youth are often at higher risk for substance use due to social, environmental and structural factors. The objectives of this study were to understand the characteristics of youth (aged 12-24 years) dying of accidental acute toxicity in Canada and examine the substances contributing to and circumstances surrounding youth ATDs.

METHODS

Data from a national chart review study of coroner and medical examiner data on ATDs that occurred in Canada between 2016 and 2017 were used to conduct descriptive analyses with proportions, mortality rates and proportionate mortality rates. Where possible, youth in the chart review study were compared with youth in the general population and youth who died of all causes, using census data.

RESULTS

Of the 732 youth who died of accidental acute toxicity in 2016-2017, most (94%) were aged 18 to 24 years. Youth aged 20 to 24 who were unemployed, unhoused or living in collective housing were overrepresented among accidental ATDs. Many of the youth aged 12 to 24 who died of accidental acute toxicity had a documented history of substance use. Fentanyl, cocaine and methamphetamine were the most common substances contributing to death, and 38% of the deaths were witnessed or potentially witnessed.

CONCLUSION

The findings of this study point to the need for early prevention and harm reduction strategies and programs that address mental health, exposure to trauma, unemployment and housing instability to reduce the harms of substance use on Canadian youth.

Stress, Environment and Early Psychosis

Existing literature provides extended evidence of the close relationship between stress dysregulation, environmental insults, and psychosis onset. Early stress can sensitize genetically vulnerable individuals to future stress, modifying their risk for developing psychotic phenomena. Neurobiological substrate of the aberrant stress response to hypothalamic-pituitary-adrenal axis dysregulation, disrupted inflammation processes, oxidative stress increase, gut dysbiosis, and altered brain signaling, provides mechanistic links between environmental risk factors and the development of psychotic symptoms. Early-life and later-life exposures may act directly, accumulatively, and repeatedly during critical neurodevelopmental time windows. Environmental hazards, such as pre- and perinatal complications, traumatic experiences, psychosocial stressors, and cannabis use might negatively intervene with brain developmental trajectories and disturb the balance of important stress systems, which act together with recent life events to push the individual over the threshold for the manifestation of psychosis. The current review presents the dynamic and complex relationship between stress, environment, and psychosis onset, attempting to provide an insight into potentially modifiable factors, enhancing resilience and possibly influencing individual psychosis liability.

Clinical characteristics of psychotic disorders in patients with childhood trauma

Childhood trauma is an important predictor of psychotic disorders, with special emphasis on physical and sexual abuse. It influences the clinical picture and course of psychotic disorders. This study was conducted in the Department of Psychiatry of the University Clinical Hospital Mostar. The sample consisted of 135 participants, aged 18 to 65 years. The screening instrument to examine cognitive status was the short version of MMSE-2. Patients' background information was collected using a sociodemographic questionnaire constructed for this study. To determine childhood trauma, the Child Abuse Experience Inventory was used to examine physical, sexual, and emotional abuse, neglect and domestic violence. The positive and negative syndrome scale scale was used to evaluate the clinical profile of psychoticism, the SSI questionnaire was used to evaluate the severity of suicidality, and the functionality of the participants was evaluated using the WHODAS 2.0. Results indicate that a significant number of participants with psychotic disorders experienced childhood trauma, an important determinant of their illness. Participants who had witnessed abuse had more severe clinical presentations (earlier onset and longer duration of illness) and more pronounced psychotic symptomatology and a lower degree of functionality. Decreased functionality is associated with witnessing abuse and physical abuse. During the civil war, a significant percentage of the participants were in childhood and adolescent development (26.7%) and exposed to frequent emotional abuse and domestic violence. As 1 traumatic event in childhood makes a person more susceptible to more traumatic experiences during life. Childhood trauma is a serious and pervasive problem that has a significant impact on the development, course, and severity of the clinical presentation of psychotic disorders. Accordingly, it is necessary to provide continuous education to mental health workers, primarily psychiatrists, regarding childhood trauma so that treatment may be approached more systematically and a plan of therapeutic interventions may be more adequately designed, which would necessarily include psychosocial support in addition to pharmacotherapy.

The relative and interactive impact of multiple risk factors in schizophrenia spectrum disorders: a combined register-based and clinical twin study

BACKGROUND

Research has yielded evidence for genetic and environmental factors influencing the risk of schizophrenia. Numerous environmental factors have been identified; however, the individual effects are small. The additive and interactive effects of multiple risk factors are not well elucidated. Twin pairs discordant for schizophrenia offer a unique opportunity to identify factors that differ between patients and unaffected co-twins, who are perfectly matched for age, sex and genetic background.

METHODS

Register data were combined with clinical data for 216 twins including monozygotic (MZ) and dizygotic (DZ) proband pairs (one or both twins having a schizophrenia spectrum diagnosis) and MZ/DZ healthy control (HC) pairs. Logistic regression models were applied to predict (1) illness vulnerability (being a proband v. HC pair) and (2) illness status (being the patient v. unaffected co-twin). Risk factors included: A polygenic risk score (PRS) for schizophrenia, birth complications, birth weight, Apgar scores, paternal age, maternal smoking, season of birth, parental socioeconomic status, urbanicity, childhood trauma, estimated premorbid intelligence and cannabis.

RESULTS

The PRS [odds ratio (OR) 1.6 (1.1-2.3)], childhood trauma [OR 4.5 (2.3-8.8)], and regular cannabis use [OR 8.3 (2.1-32.7)] independently predicted illness vulnerability as did an interaction between childhood trauma and cannabis use [OR 0.17 (0.03-0.9)]. Only regular cannabis use predicted having a schizophrenia spectrum diagnosis between patients and unaffected co-twins [OR 3.3 (1.1-10.4)].

CONCLUSION

The findings suggest that several risk factors contribute to increasing schizophrenia spectrum vulnerability. Moreover, cannabis, a potentially completely avoidable environmental risk factor, seems to play a substantial role in schizophrenia pathology.

Biological hypotheses, risk factors, and biomarkers of schizophrenia

Both the discovery of biomarkers of schizophrenia and the verification of biological hypotheses of schizophrenia are an essential part of the process of understanding the etiology of this mental disorder. Schizophrenia has long been considered a neurodevelopmental disease whose symptoms are caused by impaired synaptic signal transduction and brain neuroplasticity. Both the onset and chronic course of schizophrenia are associated with risk factors-induced disruption of brain function and the establishment of a new homeostatic setpoint characterized by biomarkers. Different risk factors and biomarkers can converge to the same symptoms of schizophrenia, suggesting that the primary cause of the disease can be highly individual. Schizophrenia-related biomarkers include measurable biochemical changes induced by stress (elevated allostatic load), mitochondrial dysfunction, neuroinflammation, oxidative and nitrosative stress, and circadian rhythm disturbances. Here is a summary of selected valid biological hypotheses of schizophrenia formulated based on risk factors and biomarkers, neurodevelopment, neuroplasticity, brain chemistry, and antipsychotic medication. The integrative neurodevelopmental-vulnerability-neurochemical model is based on current knowledge of the neurobiology of the onset and progression of the disease and the effects of antipsychotics and psychotomimetics and reflects the complex and multifactorial nature of schizophrenia.

Childhood adversity and psychotic disorders: Epidemiological evidence, theoretical models and clinical considerations

While genetic factors play a critical role in the risk for schizophrenia and other psychotic disorders, increasing evidence points to the role of childhood adversity as one of several environmental factors that can significantly impact the development, manifestations and outcome of these disorders. This paper reviews the epidemiological evidence linking childhood adversity and psychotic disorders and explores various theoretical models that seek to explain the connection. We discuss neurobiological parallels between the impact of childhood trauma and psychosis on the brain and then explore the impact of childhood adversity on different domains of clinical presentation. Finally, implications for prevention and treatment are considered, both on individual and structural levels.

Disentangling early and late onset of psychosis in women: identifying new targets for treatment

Women present a second peak of incidence of psychosis during the menopausal transition, partially explained by the loss of estrogen protection conferred during the reproductive years. In view of the lack of studies comparing sociodemographic, biological, and clinical variables and neurocognitive performance between women with early onset of psychosis (EOP) and those with late onset of psychosis (LOP), our aim was to characterize both groups in a large sample of 294 first-episode psychosis (FEP) patients and 85 healthy controls (HC). In this cross-sectional study, the participants were interviewed to gather information on sociodemographic variables. We assessed laboratory features of interest and conducted a clinical assessment of psychopathological symptoms and neurocognitive abilities. From the latter, we derived a global cognitive functioning score. Analysis of covariance (ANCOVA) was used to compare EOP and LOP groups, and each group with age-comparable HC. EOP women were more frequently single and unemployed than HC age peers. While cholesterol levels in LOP women were higher than those in EOP women, no statistically significant differences were found in leptin levels. Women with LOP presented with less severe negative symptoms and higher cognitive processing speed scores than women with EOP. Cannabis and alcohol use was greater in EOP than in LOP women. Within the total FEP group, there was a history of significantly more recent traumatic events than in the HC group. Women with EOP and LOP show several sociodemographic and clinical differences, which may be valuable for planning personalized treatment.

A family study on first episode of psychosis patients: Exploring neuropsychological performance as an endophenotype

INTRODUCTION

Family studies provide a suitable approach to analyzing candidate endophenotypes of schizophrenia, including cognitive features.

OBJECTIVE

To characterize different neurocognitive functions in a group of patients with first episode of psychosis (FEP), their first-degree relatives (parents and siblings), and healthy controls (HC), in order to identify potential endophenotypes for schizophrenia spectrum disorders (SSD).

METHODS

Participants were assessed in the context of a national project in Spain called PAFIP-FAMILIAS. They completed the same neuropsychological battery, which included tests of verbal memory, visual memory, processing speed, working memory, executive functions, motor dexterity, attention, and theory of mind. Group comparisons were performed using one-way ANOVA, followed by tests of multiple comparisons when appropriate.

RESULTS

One hundred thirty-three FEP patients were included, as well as 244 of their first-degree relatives (146 parents and 98 siblings) and 202 HC. In general, relatives showed an intermediate performance between the HC and the FEP patients in all neurocognitive domains. However, the domains of executive functions and attention stood out, as relatives (especially parents) showed similar performance to FEP patients. This was replicated when selecting patients subsequently diagnosed with schizophrenia and their relatives.

CONCLUSION

These findings suggest that executive and attention dysfunctions might have a family aggregation and could be relevant cognitive endophenotypes for psychotic disorders. The study shows the potential of exploring intra-family neuropsychological performance supporting neurobiological and genetic research in SSD.

Correlates of Aggression in Men With Methamphetamine Use Disorder: Childhood Trauma and Methamphetamine-Use Characteristics

BACKGROUND

Aggression is common among individuals with methamphetamine use disorder (MAUD) and constitutes a serious public health issue. The current study aimed to examine associations of methamphetamine-use characteristics and childhood trauma with aggression in men with MAUD.

METHODS

This cross-sectional study was conducted from December 2017 to August 2018. MAUD patients recruited from a compulsory drug rehabilitation center (n = 360) and healthy comparison subjects (n = 604) completed a survey that measured aggression and childhood trauma, using the Chinese version of Buss-Perry Aggressive Questionnaire (AQ-CV), and the short form of Childhood Trauma Questionnaire (CTQ-SF), respectively. MAUD patients also provided information on methamphetamine-use characteristics such as the age of MAUD onset, MAUD severity, and co-occurring alcohol use disorder (AUD) and tobacco use disorder (TUD) using standard or self-designed questionnaires. Chi-square tests and t-tests were used to compare childhood trauma and aggression between the MAUD and comparison groups. Multiple linear regressions were conducted to determine correlates of overall aggression and its five sub-scales among the MAUD group.

RESULTS

The MAUD group had higher childhood trauma and aggression scores than the comparison group. Within the MAUD group, age of MAUD onset, having severe MAUD, co-occurring AUD, co-occurring TUD, and childhood trauma were associated with overall aggression, with slightly different correlates found for its five sub-scales.

CONCLUSIONS

Our study shows a high level of childhood trauma and aggression in the MAUD group. Both methamphetamine-use characteristics (age of MAUD onset, severe MAUD, co-occurring AUD/TUD) and childhood trauma were associated with aggression in MAUD. Our findings provide useful information on potential risk factors for aggression and inform future longitudinal research to establish causal relationships between these factors and aggression to guide further prevention and treatment programs.

Cannabis-induced dysphoria/paranoia mediates the link between childhood trauma and psychotic-like experiences in young cannabis users

Childhood trauma (abuse and neglect) is a major risk factor for cannabis use disorder and psychotic-spectrum disorders. Psychotic-like experiences (PLEs) in young people who use cannabis may be an early indicator of psychosis risk following cannabis use. We examined whether (i) childhood trauma moderates the association between cannabis use and PLEs, (ii) the association between childhood trauma and cannabis use is mediated by subjective effects of cannabis (euphoria and dysphoria/paranoia), and (iii) the association between childhood trauma and PLEs is also mediated by these subjective effects. Participants were 2630 cannabis users (aged 16-25) recruited online. They were asked to complete a cross-sectional survey measuring cannabis and other substance use, childhood trauma, PLEs, and the subjective effects of cannabis (euphoria and dysphoria/paranoia). A significant interaction indicated that the effect of cannabis on PLE frequency was stronger for individuals with more severe childhood trauma. Childhood trauma was also associated with greater cannabis use and PLE frequency, both of which were mediated by subjective dysphoria/paranoia when using the drug. This suggests childhood trauma is associated with greater PLEs in young people who use cannabis, which may be linked with an increased susceptibility to the dysphoric/paranoid subjective effects when using the drug. Childhood trauma should be addressed early in young people who use cannabis to mitigate the psychosis-associated harms of the drug.

Primary Psychosis: Risk and Protective Factors and Early Detection of the Onset

Primary psychosis, which includes schizophrenia and other psychoses not caused by other psychic or physical conditions, has a strong impact worldwide in terms of disability, suffering and costs. Consequently, improvement of strategies to reduce the incidence and to improve the prognosis of this disorder is a current need. The purpose of this work is to review the current scientific literature on the main risk and protective factors of primary psychosis and to examine the main models of prevention, especially those related to the early detection of the onset. The conditions more strongly associated with primary psychosis are socio-demographic and economic factors such as male gender, birth in winter, ethnic minority, immigrant status, and difficult socio-economic conditions while the best-established preventive factors are elevated socio-economic status and an economic well-being. Risk and protective factors may be the targets for primordial, primary, and secondary preventive strategies. Acting on modifiable factors may reduce the incidence of the disorder or postpone its onset, while an early detection of the new cases enables a prompt treatment and a consequential better prognosis. According to this evidence, the study of the determinants of primary psychosis has a pivotal role in designing and promoting preventive policies aimed at reducing the burden of disability and suffering of the disorder.

Using Mendelian randomization analysis to better understand the relationship between mental health and substance use: a systematic review

BACKGROUND

Poor mental health has consistently been associated with substance use (smoking, alcohol drinking, cannabis use, and consumption of caffeinated drinks). To properly inform public health policy it is crucial to understand the mechanisms underlying these associations, and most importantly, whether or not they are causal.

METHODS

In this pre-registered systematic review, we assessed the evidence for causal relationships between mental health and substance use from Mendelian randomization (MR) studies, following PRISMA. We rated the quality of included studies using a scoring system that incorporates important indices of quality, such as the quality of phenotype measurement, instrument strength, and use of sensitivity methods.

RESULTS

Sixty-three studies were included for qualitative synthesis. The final quality rating was '-' for 16 studies, '- +' for 37 studies, and '+'for 10 studies. There was robust evidence that higher educational attainment decreases smoking and that there is a bi-directional, increasing relationship between smoking and (symptoms of) mental disorders. Another robust finding was that higher educational attainment increases alcohol use frequency, but decreases binge-drinking and alcohol use problems, and that mental disorders causally lead to more alcohol drinking without evidence for the reverse.

CONCLUSIONS

The current MR literature increases our understanding of the relationship between mental health and substance use. Bi-directional causal relationships are indicated, especially for smoking, providing further incentive to strengthen public health efforts to decrease substance use. Future MR studies should make use of large(r) samples in combination with detailed phenotypes, a wide range of sensitivity methods, and triangulate with other research methods.

Childhood maltreatment and social functioning in psychotic disorders: a systematic review protocol

Background: Childhood maltreatment (CM) is thought to play a key role in the etiology and course of psychotic disorders (PD). In addition, CM is related to neurobiological and clinical characteristics that can lead to poor social functioning. However, the extent to which CM and social functioning are directly associated in individuals with PD, is unclear. Therefore, we aim to systematically review the literature to provide an estimate on the strength of the association between CM and different domains of social functioning in PD and to summarize potential moderators and mediators of this association.Methods and analysis: To identify relevant studies, we will systematically search the following databases: Pubmed (Medline), PsycInfo, Embase, Web of Science (Core Collection), and Pilots (trauma), manually search reference lists and contact experts in the field. Studies will be included if they investigate and report on the association between CM (exposure) and social functioning (outcome) in adults with PD. Two independent reviewers will screen titles, abstracts and full texts according to eligibility criteria, perform data extraction and assess study quality according to a modified version of the Newcastle-Ottawa Scale.Analysis: Effect estimates will be pooled in a meta-analysis. Heterogeneity and publication bias will be assessed and the effects of potential moderators (genetic factors, type of diagnosis, duration of illness, type of CM and age at the time of CM exposure) will be analyzed using meta-regressions. Candidate moderators and mediators (neurocognition, cognitive schemas, comorbidities, stress sensitivity, attachment) will be also examined qualitatively.Ethics and dissemination: Because this review will make use of already published data, ethical approval will not be sought. This work has the potential to inform upcoming investigations on the association between the exposure to CM in PD and social functioning. PROSPERO registration number CRD42020175244.