We review recent developments on risk factors in schizophrenia. The way we think about schizophrenia today is profoundly different from the way this illness was seen in the twentieth century. We now know that the etiology of schizophrenia is multifactorial and reflects an interaction between genetic vulnerability and environmental contributors. Environmental risk factors such as pregnancy and birth complications, childhood trauma, migration, social isolation, urbanicity, and substance abuse, alone and in combination, acting at a number of levels over time, influence the individual’s likelihood to develop the disorder. Environmental risk factors together with the identification of a polygenic risk score for schizophrenia, research on gene–environment interaction and environment–environment interaction have hugely increased our knowledge of the disorder.

/pdf/non-genetic-factors-in-schizophrenia-3n58gxz765.pdf

Non-Genetic Factors in Schizophrenia

Aims:
To summarize evidence on the frequency and predictors of health‐care utilization among people who use illicit drugs.

Design:
Systematic search of MEDLINE, EMBASE and PsychINFO for observational studies reporting health‐care utilization published between 1 January 2000 and 3 December 2018. We conducted narrative synthesis and meta‐analysis following a registered protocol (identifier: CRD42017076525).

Setting and participants:
People who use heroin, powder cocaine, crack cocaine, methamphetamine, amphetamine, ecstasy/3,4‐methyl​enedioxy​methamphetamine (MDMA), cannabis, hallucinogens or novel psychoactive substances; have a diagnosis of ‘substance use disorder’; or use drug treatment services.

Measurements:
Primary outcomes were the cumulative incidence (risk) and rate of care episodes in three settings: primary care, hospital admissions (in‐patient) and emergency department (ED).

Findings:
Ninety‐two studies were included, 84% from North America and Australia. Most studies focused on people using heroin, methamphetamine or crack cocaine, or who had a diagnosis of drug dependence. We were able to conduct a meta‐analysis of rates across 25 studies reporting ED episodes and 25 reporting hospital admissions, finding pooled rates of 151 [95% confidence interval (CI) = 114–201] and 41 (95% CI = 30–57) per 100 person‐years, respectively; on average 4.8 and 7.1 times more often than the general population. Heterogeneity was very high and was not explained by drugs used, country of study, recruitment setting or demographic characteristics. Predictors of health‐care utilization were consistent across studies and included unstable housing, drug injection and mental health problems. Opioid substitution therapy was consistently associated with reduced ED presentation and hospital admission. There was minimal research on health‐care utilization by people using ecstasy/MDMA, powder cocaine, hallucinogens or novel psychoactive substances.

Conclusions:
People who use illicit drugs are admitted to emergency department or hospital several times more often than the general population.

/pdf/frequency-of-health-care-utilization-by-adults-who-use-1yp4sn6pzv.pdf

Frequency of health-care utilization by adults who use illicit drugs: a systematic review and meta-analysis

https://onlinelibrary.wiley.com/doi/pdf/10.1002/wps.20655

Migration, ethnicity and psychoses: evidence, models and future directions.

Does Cannabis Cause, Exacerbate or Ameliorate Psychiatric Disorders? An Oversimplified Debate Discussed.

There is a high prevalence of cannabis use reported in non-affective psychosis Early prospective longitudinal studies conclude that cannabis use is a risk factor for psychosis, and neurochemical studies on cannabis have suggested potential mechanisms for this effect Recent advances in the field of neuroscience and genetics may have important implications for our understanding of this relationship Importantly, we need to better understand the vulnerability x cannabis interaction to shed light on the mediators of cannabis as a risk factor for psychosis Thus, the present study reviews recent literature on several variables relevant for understanding the relationship between cannabis and psychosis, including age of onset, cognition, brain functioning, family history, genetics and neurological soft signs (NSS) in non-affective psychosis Compared with non-using non-affective psychosis, the present review shows that there seem to be fewer stable cognitive deficits in patients with cannabis use and psychosis, in addition to fewer NSS and possibly more normalized brain functioning, indicating less neurobiological vulnerability for psychosis There are, however, some familiar and genetic vulnerabilities present in the cannabis psychosis group which may influence the cannabis pathway to psychosis by increasing sensitivity to cannabis Furthermore, an earlier age of onset suggests a different pathway to psychosis in the cannabis-using patients Two alternative vulnerability models are presented to integrate these seemingly paradoxical findings

/pdf/the-cannabis-pathway-to-non-affective-psychosis-may-reflect-30jm6wy762.pdf

The Cannabis Pathway to Non-Affective Psychosis may Reflect Less Neurobiological Vulnerability

Risk of psychosis and internal migration: Results from the Bologna First Episode Psychosis study.

The impact of substance use at psychosis onset on First Episode Psychosis course: Results from a 1 year follow-up study in Bologna

Psychiatric consequences of disasters in Italy: A systematic review

The term “Psychosis,” from Greek ψυχή (psyche), “mind/soul,” and -ωσιζ (-osis), “abnormal condition or derangement,” indicates a mental state characterized by a set of positive and negative “psychotic” symptoms. Psychotic disorders have a multifactorial etiology. Many epidemiological studies have reported how rates of substance misuse, especially cannabis, are consistently higher in first episode psychosis patients. Another very important predictor of psychosis is migration history. It has been widely replicated that rates of schizophrenia are higher among migrant and ethnic minority groups. Little is known on the association between these two risk factors in the development of new-onset psychosis. One of the studies conducted so far have associated the use of cannabis to a greater risk of developing psychotic disorders for the second generation of migrants, but not with the first generation. Further studies are needed to emit light on the correlation of these two risk factors on the development of psychotic disorders.

Arnisa Kokona

Papers

Risk of psychosis and internal migration: Results from the Bologna First Episode Psychosis study.

The impact of substance use at psychosis onset on First Episode Psychosis course: Results from a 1 year follow-up study in Bologna

Psychiatric consequences of disasters in Italy: A systematic review

Cannabis, Migration, and Psychosis Onset