The effect of ethnic density on psychosis incidence

Members of some ethnic groups have a higher than usual risk of developing a severe mental illness such as schizophrenia or bipolar disorder. Some studies have linked this to how isolated people from some ethnic groups are, so that, for example, black people living in mostly white areas may be more at risk. This has been termed the ethnic density effect. Because these are relatively uncommon diseases it has been difficult to look at any more than one, very crudely defined, ethnic group at a time. Using a very large collection psychiatric records I will be able to compare the experiences of a wide range of ethnic groups and look in more detail at what might be causing this ethnic density effect. It has also been suggested that this effect may be much more relevant to some types of severe mental illness, such as schizophrenia, than others. By accessing such a large collection of health records I will be able to address this question in more detail than has been possible before.

The study will look at how living in a particular type of area can effect one's mental health. This is particularly difficult to research as it is hard to identify the relevant neighbourhood when looking at patient records. Typically studies have relied on the address where someone was living when they were first diagnosed. However, people with a mental illness often change address as they become ill, making it difficult to establish which area is relevant. A number of researchers looking at this problem have concluded that, for research to progress, better methods are needed to assess neighbourhoods effects. The psychiatric records that I will use in this study include information about the areas where patients have lived at different times in their life. This, along with further detailed information about each patient's life history, will allow me for the first time to look much more carefully at how living in a particular neighbourhood may affect someone's mental health.

To find out more about this from the patient's perspective I will also interview people who have suffered a severe mental illness, chosen from ethnic groups and neighbourhoods that most clearly show this ethnic density effect. The results of these interviews will then be used to guide the analysis of patient records that will make up the main part of the study. It has also been argued that, as this is an international phenomena, it is important that studies compare results in more than one country. Therefore I will also do a similar study using health records for patients in the Utrecht region in Holland to see how a different context changes the study results.

The study is intended to find out more about what is causing this increased risk in some ethnic groups. The results of this research will therefore have the potential to help prevent this occurring in the future. By finding out more about what is happening in these groups the study will add to what is generally known about the causes of these diseases and ultimately help inform future treatments and preventative measures.

STUDY AIM
to investigate the effect of ethnic density on the risk of psychosis among black and minority ethnic (BME) groups
STUDY OBJECTIVES
to assess:
1) whether greater ethnic density, at neighbourhood area level, is inversely related to psychosis incidence for members of BME groups, after prior address history is accounted for
2) whether there are significant differences in this effect between ethnic groups,
3) whether this effect is different for sub-groups of psychotic illness (affective / non-affective)
4) whether this differs at different neighbourhood levels
5) how this might differ in different urban areas, both nationally and internationally
6) possible underlying mechanisms behind these effects reflecting, for example, aspects of social cohesion, social support and social alienation.
METHODOLOGY
I will use a mixed methods design:
Study 1 - Initial analysis using detailed psychiatric linked to stratified area census records (covering 180,000 mental health service users in SE London, including detailed free text allowing address history to be tracked prior to illness onset) - meeting objectives 1 - 4.
Study 2 - Using primary care records (covering 900,000 patients in 1 SE London and 3 East London boroughs) to extend the analysis (validating against the above linked psychiatric records) - obj. 1 - 5.
Study 3 - Qualitative study of life history accounts of neighbourhood factors (comparing accounts in high and low ethnic density areas to generate hypotheses as to mechanisms behind ethnic density effect) - obj. 6
Study 4 - Further analysis of linked records (to investigate possible mechanisms behind the ethnic density effect informed by study 1-3) - obj. 6
Study 5 - International comparison study (apply analyses to similar data collected in Netherlands)- obj. 5.
SCIENTIFIC AND MEDICAL OPPORTUNITIES
This has the potential to illuminate mechanisms behind ethnic differences in psychosis that would inform treatment and prevention.

The results of the proposed study will add to what is known about the causes of psychotic illness and therefore be relevant to those concerned with prevention and treatment measures and mental health in general, including: clinicians, counsellors and psychologists, mental health service users and carers and relevant voluntary sector organisations. Ultimately the question "why do some people develop a severe mental illness and not others" is of interest to everyone, not just mental health professionals. The study also has a wider relevance in that it has the potential to tell us something about the nature of social isolation as it is experienced by particular ethnic groups and how this could be pathogenic. The results could therefore inform much wider debates around ethnicity, assimilation and integration that are of interest to policy makers, the social care and voluntary sector and the general public. This is still a relatively new field of research and, so far, the ethnic density effect has been studied in very few ethic groups. Mine will be the first to look at the experience of clinical psychosis among the Indian, Pakistani and Bangladeshi communities in this way and therefore will also be of direct, and immediate, interest to these communities. Through an extensive programme of dissemination activity the study could therefore have an impact within the duration of the fellowship.

Although the study is not directly concerned with an intervention the results of the study could inform future interventions and therefore have an impact in the long term. One area, for example, is that of treatment measures designed to address the social isolation of service users. Although research in this area is still at an early stage, this study intends to reveal factors behind the elevated rates of psychosis relating to the social isolation of particular ethnic groups. What we learn about these factors could then inform relevant interventions . For example, a recent initiative to develop a social capital intervention addressing the social isolation of mental health service users in London (see: http://connectingpeoplestudy.wordpress.com/about/) would directly benefit from the results of this study. This is designed to find out how health and social care workers can assist individuals recovering from psychosis to access social capital. On the basis that initiatives such as this could potentially be put in place within 2 to 3 years the results of my study could inform patient care within the next decade.

The study could also identify communities and areas where service users from particular ethnic groups would benefit from mental health services specifically tailored to their ethnic group or, alternatively, measures to help them access ethnic specific services in other areas.

There are other potential areas where the study could influence patient care. For example, it may be that language fluency plays a role in psychosis risk for some of these groups and therefore attention could be paid to language services for mental health service users. It may be that people from particular religious faiths are more at risk than others, in which case resources could be more effectively targeted at these faith communities. Also public health information designed to improve people's awareness of mental illness and sources of support could be targeted at particular groups identified in the study as most isolated and at risk.

The study could also inform wider community services - where particular groups are highlighted as being vulnerable this study could inform housing policies, travel links, town planning measures and the provision of local ethnic specific resources and communications. By successfully disseminating the results via local health trusts, local authority policy makers and other agencies this could potentially have a long term effect.