Migrants at elevated risk for psychotic disorders, but not for non-psychotic bipolar disorder – new PsyLife paper

by Ashild Kummen

Image result for migrationMigration can be a difficult process, involving a multitude of stressors. This may make some migrants more vulnerable to mental health problems, and previous research have found migrants to be at an elevated risk for psychotic disorders, especially with visible minorities, such as people from black Caribbean and African backgrounds in the UK . In regard to bipolar disorders, however, the research is more mixed, and enquiries have rarely distinguished between bipolar disorders with and without psychotic symptoms.

A new paper from our Ph.D. student Jennifer Dykxhoorn, published today in Psychological Medicine, sheds light on whether the increased risk of psychotic disorders extends to bipolar disorder with and without psychosis. In her paper, Jen hypothesised that migrants were at elevated risk for schizophrenia and affective psychoses (such as bipolar disorder with psychotic features), but not for bipolar disorders without psychotic symptoms. Longitudinal data from almost 1.8 million Swedish residents born between 1982-1996 were collected, with differences by migrant status, age-at-migration and region of origin investigated. Consistent with previous findings , we predicted that migration during early childhood would increase the risk of being diagnosed with a psychotic disorder.

Findings

Compared with the Swedish-born population, migrants and their children were at elevated risk for all psychotic disorders. This included schizophrenia and schizoaffective disorder, where migrants and their children were, on average, twice as likely to be diagnosed. First-generation migrants were also at double the risk for other types of non-affective psychoses. Rates of bipolar disorder with psychosis were also elevated in migrants and their children by 42% and 22%, respectively, compared to the Swedish-born population. In stark contrast,  migrants were up to 40% less likely to be diagnosed with non-psychotic bipolar disorders than the Swedish-born population. For second-generation migrants, risk of non-psychotic bipolar disorder was similar to Swedish-born rates.

While we predicted that migrating during early childhood would elevate risk of psychotic disorders, our findings did not support this. Instead, there was a pattern of increased risk at all ages of immigration to Sweden for psychotic disorders.. By contrast, all ages at immigration were associated with lower risk for bipolar disorder, except for those who migrated during infancy, where incidence rates were closer to the Swedish-born population.

In accordance with previous research by the PsyLife team , African migrants were at highest risk for all psychotic outcomes, including being five times more likely to be diagnosed with schizophrenia. In total, migrants from all origins (except other Nordic origin) were at elevated risk for all psychotic disorders, compared to the Swedish-born population.

Possible explanations

Migrants are exposed to several difficulties relating to the process of migrating and the minority status. Jen’s paper found that the incidence rates for psychotic disorder and bipolar disorders (without psychotic symptoms) is largely different, with higher risk for psychotic disorders and lower risk for bipolar disorders compared to the Swedish-born population. This could suggest that the stressors of migrating and post-migration life have a specific effect on developing psychotic disorders. This is consistent with some research on the neurodevelopmental origins of psychotic and non-psychotic bipolar disorders, conveying these origins are distinct. For example, patients with schizophrenia and bipolar disorders with psychotic features are observed to have premorbid cognitive deficits, which have not been consistently found in non-psychotic affective disorders (Reichenberg et al., 2002; Trotta et al., 2014). Our research suggests further work is now required to test whether certain environmental factors impact on specific neurobiological pathways to influence the occurrence of certain types of mental health problem.

 

PsyLife references

Other references

  • Reichenberg, A., Weiser, M., Rabinowitz, J., Caspi, A., Schmeidler, J., Mark, M., Kaplan, Z, & Davidson, M. (2002). A population-based cohort study of premorbid intellectual, language and behavioural functioning in patients with schizophrenia, schizoaffective disorder, and nonpsychotic bipolar disorder. Psychiatry: Interpersonal and Biological Processes, 159, 2027-2035.
  • Trotta, A., Murray, R. M & MacCabe, J. H. (2014). Do premorbid and post-onset cognitive functioning differ between schizophrenia and bipolar disorder? A systematic review and meta-analysis. Psychological Medicine, 45, 381-394.

PsyLife research in Europe’s cultural capitals

It’s an exciting week for the PsyLife group. We’re presenting no fewer than 6 research papers in two of Europe’s most historic cultural capitals – Vienna and Florence.

Recent PsyLife Phd graduate, Dr Hannah Jongsma, and current PhD student Jean Stafford will both be in Florence for the 6th Biennial conference of the Schizophrenia International Research Society  Hannah will be speaking as part of a symposium (Sala Verde, Sat 7 April, 10-12pm) on the prevention of psychosis, talking about her recent findings from the EU-GEI study . Congratulations to Jean, who won a Young Research travel award to attend the conference, and will be giving a poster presentation on variation in the incidence of very-late onset psychotic disorders using nationwide longitudinal cohort data. Her poster is S134 and she will be presenting in Poster Session III on Saturday 7th April, 12-2pm.

Meanwhile, over in Vienna, we have a PsyLife symposium at the 18th 19th(!) Section meeting of European Psychiatric Association’s Epidemiology and Social Psychiatry section. Our symposium, entitled Environments and psychosis: examining the causal evidence will feature our latest findings from the ALSPAC birth cohort and the SEPEA study on how neighbourhood environments are related to psychotic outcomes and comorbid personality disorders. We have talks from Dr James Kirkbride, Dr Francesca Solmi, Ka-Young Ban (PhD student) and Tayla McCloud (rortation PhD student). Do come along and find out more: Kursraum 22, Friday 6th April, 2-3.30pm.

Finally, we wanted to say a massive thank you and congratulations to Francesca, who will be leaving the PsyLife group to begin her own Sir Henry Wellcome Fellowship on the epidemiology of eating disorders. Francesca has published several key papers with the group in her three years here , with several more still to come. We are sure you will go on to great successes, and thank you for being such an inspiring, helpful and knowledgeable member of the group!

References

Congratulations Dr Hannah Jongsma!

Image result for hannah jongsmaThe PsyLife group are thrilled that group PhD student Hannah Jongsma passed her viva at the University of Cambridge last week, with a recommendation that she be awarded a PhD following (just two) minor corrections to her thesis. In her thesis, entitled The role of the social environment in explaining variance in incidence of psychosis and higher rates of disorder in minorities,  Dr Jongsma explored variation in the incidence and risk of psychotic disorders using epidemiological data from the EU-GEI study. In particular she was interested in understanding variation in incidence by place, and last month published the first output from her thesis in JAMA Psychiatry, in a paper exploring reasons for 10-fold variation in rates of psychotic disorder across 17 centres in the EU-GEI study . She was also interested in understanding variation by ethnicity and migrant status, exploring the roles that psychosocial disadvantage and social distance played on these factors. 

We would like to congratulate Dr Jonsgma on her success, and wish her the best of luck in her future career. Dr Jonsgma will continue as a postdoctoral research associate in the Department of Psychiatry at the University of Cambridge, and we look forward to seeing more outputs published from her PhD over the next year or so. 

Well done!

Reference

Epidemiology in Schizophrenia Research: Moving from Trait to State of the Art

Image result for random news cartoonThis weekend marks the beginning of the 16th International Congress on Schizophrenia Research, the biennial international meeting this year taking place in the pleasant climes of San Diego, US. The meeting offers a chance to hear about groundbreaking research across a range of domains, including cell biology, animal models, cognitive neuroscience and psychiatric genetics. Moreover, there is a collaborative, friendly atmosphere, with junior and senior colleagues engaging in meaningful, critical discourse in and out of the formal sessions.

Despite the warm reception, the inclusion of epidemiological research in the Congress’ program has traditionally been cool. The 16th meeting will not reverse that trend, with one session devoted specifically to epidemiological research, with 10 talks crammed into a mammoth two and a half hour session on Saturday afternoon. To an outsider – or one of the forty or so people attending the sparsely populated ballroom – there will have been little to convince the field, or future programme committees, that epidemiology should move from a mild trait of schizophrenia research to a discipline which should be emblematic of the state of all science conducted within psychiatric and schizophrenia research.

Of the ten scheduled talks, two speakers did not show up, apparently with no prior apologies to the chair. Although there might have been genuine, unavoidable reasons for these cancellations, the lack of courtesy shown to the audience, other speakers, chair and meeting organisers manifests itself as apathetic; a trait that will rarely endear the discipline to future conference committees. To get an oral presentation accepted at a major international meeting should be viewed as an honour – if in doubt, one needs to look no further than the thousands of wonderful poster presentations at ICOSR, of whom I suspect any one would be delighted to receive a wider audience for their research.

Perhaps most concerningly, the quality of the epidemiological research on show was not able to shine through with all the wonderful, disciplined and principled methods that good epidemiological training should permit. In the age of big data, computational psychiatry and causal inference, the session was pockmarked by a series of poorly controlled studies, negative findings (of themselves potentially important, if we can establish that the findings are likely to be true, having considered the caveats of possible chance, bias and confounding) and problematic interpretation of results and their translational meaning for public mental health. There were some highlights in the session, notably some interesting work on polygenetic risk scores which appear not to confound associations between urban living and later psychosis risk, despite people in urban areas having slightly higher PRS for schizophrenia.

As a field, those of us in psychiatric epidemiology have a duty to do more. We need to engage with modern, state of the science with regard to causal inference and other techniques which potentially allow observational epidemiology to inform psychiatric research about aetiological mechanisms in the same way that experimental research has the potential to. Before that, good basic training in epidemiology can serve the whole field of schizophrenia research. Some of psychiatry’s greatest thinkers come from a background in epidemiological training and reasoning. Our core business as epidemiologists is not to show associations between risk factor X and outcome Y, but to bring to bear the principles of designing unbiased, unfounded and robust studies to answer clear research questions with carefully formulated hypotheses. On our MSc in Clinical Mental Health Sciences at UCL, which attracts 80 budding psychologists each year, the epidemiological training our students receive does not seek to teach them how to conduct an epidemiological study, but how to apply critical thinking and epidemiological reasoning to any research “evidence” they may encounter in their future careers. In this respect, our discipline should be proud; we can take a lead in research design across all areas of schizophrenia research, whether in the cell, the mouse or the human. Never has there been a more exciting time to work in mental health research; converging data from social neuroscience, neuropsychology, psychiatric genetics and epidemiology suggest a mix of genetic and environmental factors are critical to shaping psychosis vulnerability. Epidemiologists need to be central to those conversations.

Fortunately, great epidemiological research in schizophrenia does exist, addressing fundamental questions of variance in incidence, prevalence and causes worldwide. For example, forthcoming data from the international multi-site European Network of National Schizophrenia Networks Studying Gene Environment Interactions (EU-GEI) study has brought together a multidisciplinary team of researchers worldwide to test vital questions about how genetic and environmental factors may combine to increase psychosis risk. Such major consortia are never undertaken lightly, and the fruits of this study – amongst many other carefully designed epidemiological studies – should come to bear in future meetings. Until then, let’s promote and celebrate the uses of epidemiological reasoning throughout schizophrenia research, and be part of the conversation about the strength of evidence across the state of science in our field.

Are cats bad for your mental health? Probably, not.

Over the past few years, a number of scientific studies and media outlets have reported that Toxoplasma Gondii (T. Gondii) infection could increase a person’s risk of experiencing adverse mental health outcomes – including schizophrenia, suicide, and intermittent rage disorder.

Since domestic cats are the primary hosts of T. Gondii (i.e., they provide an environment within which this parasite can reproduce) some people have speculated that cat ownership may put people at increased risk of mental illness, by exposing them to T. Gondii infection. While a handful of small studies have found evidence to support a link between cat ownership and psychosis, most of these investigations had serious methodological limitations (e.g.: relying on recall of past cat ownership, small sample sizes, missing data, lack of control for other explanations), which may have biased their findings.

To tackle these limitations, we used data from a large, longitudinal sample of approximately 5,000 children, a sub-group of 14,000 children born in the former region of Avon, (UK) between 1991 and 1992. Unlike previous studies, we were able to follow people over time, from birth to late adolescence, and address a number of the limitations of previous studies, including controlling for alternative explanations (including socioeconomic status, ethnicity, other pet ownership and over-crowding) and taking into account missing data. We studied whether mothers who owned a cat: 1) while pregnant; 2) when the child was 4 years old; and 3) 10 years old, were more likely to have children who reported psychotic symptoms (e.g.: experiences of visual or auditory hallucinations, and of paranoia) in early (age 13) and late adolescence (age 18).

We found that children who were born and raised in households that included cats at any time period were not at a higher risk of having psychotic symptoms when they were 13 or 18 years old. This finding in a large, representative sample was robust against issues of missing data and alternative explanations. Although most people who experience psychotic symptoms in adolescence will not develop schizophrenia later in life, they can indicate an increased risk for such disorders.

It is important to remember that there is evidence linking T. Gondii exposure in pregnancy to risk of miscarriage and stillbirth or health complications in offspring. We therefore recommend that pregnant women should continue to avoid handling soiled cat litter and other sources of T. Gondii infection (such as raw or undercooked meats or unwashed fruit and vegetables). That said, data from our study suggests that cat ownership during pregnancy or in early childhood does not pose a direct risk for later offspring psychotic symptoms.

Psychosis in the field

Click to visit the study webpage (external)New research led by Dr James Kirkbride from the PsyLife group, Division of Psychiatry, UCL, has shown how psychosis risk varies in more rural populations than previously studied in England. The findings, published last week in the American Journal of Psychiatry, reveal that rural regions see a significant rate of new cases of psychotic disorder in their populations. This is important because service planners need to ensure all people developing a first episode of psychosis can get quick, timely access to specialist mental health services such as Early Intervention teams.

The study was conducted in the East of England, in three counties – Cambridgeshire, Norfolk and Suffolk – and tried to identify all young people (aged between 16 and 35 years old) presenting to mental health services for the first time due to psychosis over a 3.5-year period. During this time, the study identified over 680 people who met diagnostic criteria for first episode psychosis living in this region, corresponding to an incidence rate of 34 new cases per 100,000 people per year.

The study also revealed that the risk of developing psychosis varied by important characteristics of both individuals and their environments. For example, although the study was conducted in a more rural setting than many previous epidemiological studies of this type , the authors found that the rate of disorder still varied according to how densely populated and deprived the environment was. Rates of psychotic disorder were relatively stable in most parts of the region, but rose in the most deprived and most densely populated regions. While this data is in keeping with earlier research , the study extends previous knowledge by suggesting that there may be a threshold effect in operation; below a certain level of population density or deprivation, there is no increase in risk, but once a certain level is reached, risk begins to shift. This research has not previously been possible in studies which have tended to be conducted in more urban environments.

The study also found variation by individual level factors. As previously established, men were almost twice as likely to experience a first episode of psychosis than women, particularly in their late teens and early twenties when risk is highest for both sexes. There was some evidence that rates were also raised in black and minority ethnic groups, but another paper from the same study will address this issue in more detail, and is currently under review.

You can read the full version of these findings here, or read about further overage of the findings from Psychiatric News and Medscape.

Reference

A Big Week for PsyLife

336437537It’s been quite a week for the PsyLife lab. First off, we’re delighted to say that one of our PhD students – Jen Dykxhoorn – successfully passed her PhD upgrade at UCL. While we weren’t surprised by this, it reflects a huge amount of work Jen has put in to her PhD on migration and psychosis in the first year. She’s currently writing up some results from her first study on this topic, which we’ll be submitting soon for publication. Jen has developed a great program of research as part of her PhD over the next 3 years, which we’re very excited about. Congrats Jen! Jen’s research is funded by Mental Health Research UK, with subsidiary funding from the Royal Society and Wellcome Trust.

 

We’re also delighted to announce that another PhD student – Jean Stafford – has joined the group to do a mixed epidemiological and psychological PhD on old age psychosis. She’ll be co-supervised by Dr James Kirkbride and Prof Rob Howard in the Division of Psychiatry. Jean spent 3-months with us last year as part of her MRC-sponsored first year PhD rotation scheme. Welcome along Jean!

 

We also welcome Dr Daria Monteforte from the University of Verona who joins us for a 6-month research visit. Daria is a psychiatrist specialising in psychosis. She’ll be gaining research experience during her visit with us. You can read more about what Daria’s up to here.

 

The PsyLife group would also like to pass on its congratulations to the MSc students who did student projects with us in 2015-16. All the projects we supervised addressed interesting epidemiological and mental health service issues with respect to psychosis, and we were impressed by the overall quality. Hopefully several of these will be submitted for peer-reviewed publication in the coming months. Dawid Gondek begins a PhD in longitudinal epidemiology of healthy ageing at the Institute of Education with Professor George Ploubidis, while Lucy Richardson has joined the REACH study with Professor Craig Morgan at the IoPPN as a Research Assistant. Mohammedi Abdolali continues his clinical work as a psychiatrist, armed with new insights from his MSc experiences. Finally, well done to Tom Steare, who continues his studies in mental health.

 

On a final note, a major publication from the PsyLife group has been published this week in the American Journal of Psychiatry. The paper investigates the epidemiology of first episode psychotic disorders, as seen through Early Intervention in Psychosis services in a rural population in England. Until now, very little epidemiological research has been conducted in EIP settings or in rural populations, and this study is an attempt to fill this gap. The paper has also been covered by Psychiatric News.

More Student Success in the PsyLife Lab

Bio picHere in the PsyLife lab we busy working away on lots of exciting hypotheses regarding how the social environment is linked to a greater risk of experiencing psychosis at a later time point.

Now, one of our first-year PhD students, Jen Dykxhoorn has achieved further recognition for her PhD which will focus on the role of social factors underlying the raised rates of psychotic disorders amongst migrants and their descendants. Jen has been awarded a prestigious UCL Overseas Research Scholarship in support of her PhD.

We’re delighted Jen’s research potential has been recognised at this early stage in her career, and we are excited about the progression she will make in her studies over the next three years. Jen’s PhD research is also supported by the Mental Health Research UK (MHRUK)’s John Grace QC Scholarship. Once again, congratulations to Jen, and stay tuned here for exciting findings from her and the rest of the group.

SIRS Travel Award for PsyLife PhD student!

SIRS meetingThis weekend will see the start of the eagerly awaited 5th Biennial Schizophrenia International Research Society (SIRS) conference, taking place in Florence, Italy. The conference will bring together international researchers from all areas of schizophrenia research to discuss the latest findings from the field. It promises to be an excellent meeting, and two members of the PsyLife group, Dr James Kirkrbide and PhD student Hannah Jongsma, will be presenting some of their findings.

We’re delighted to announce that Hannah has won a prestigious SIRS Young Investigator Travel Award to attend the conference. Congratulations! Hannah is in the second year of her PhD on the role of social and environmental risk factors in schizophrenia and other psychoses. To receive this international award is a major achievement and highlights Hannah’s dedication and growing expertise in the field. Hannah will be presenting her findings on cross-national variation in the incidence of psychotic disorders using data from the EU-GEI study. If you are at the conference, her talk will be on Tuesday 5th April, from 3.15pm, in the session on “Epidemiology: roles for environmental risk factors”. James will be presenting his work on age-at-migration in the same session. Do join us if you can.

See you in Florence!

Ciao!

 

Full list of PsyLife presentations at SIRS 2016

  • Hannah Jongsma: Incidence of psychotic disorders in England, France, Italy, the Netherlands, Spain and Brazil: Data from the EU-GEI study, Tues 5th April, 4.30pm-4.45pm: Symposium: Epidemiology: roles for environmental risk factors
  • James Kirkbride: Age-at-migration and risk of first episode psychosis in England: epidemiological evidence from the SEPEA study, Tues 5th April, 3.45-4pm, Symposium: Epidemiology: roles for environmental risk factors
  • James Kirkbride: (Poster S157): The Epidemiology of first episode psychosis in early intervention  in Psychosis services: findings from the SEPEA study, Poster session 1, Sunday 3rd April, 11am – 1pm.

 

Psychosis incidence in refugees to Sweden – cohort study of 1.3 million people

Working with colleagues at the Karolinska Institute we’ve shown that the risk of schizophrenia and other psychotic disorders is raised in refugees to Sweden by up to 3 times that of the Swedish-born population. This risk, was on average, 66% higher than the risk in other (non-refugee) migrants from the same regions of origin. These findings suggest that the additional psychosocial adversities faced by refugee groups may be important in the aetiology of psychosis. You can see a video abstract highlighting the work here, or read the full article published in the BMJ. This work was jointly conducted by our group at UCL and the Department of Public Health Sciences at the Karolinska Institute.