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Psychosis, sometimes called schizophrenia, is a psychological state characterised by symptoms such as paranoia and hallucinations. In England, one person in every 100 will be diagnosed with a psychotic disorder at some point in their lives. Disturbingly, evidence gathered from Western nations suggests that immigrants experience psychosis at rates two to five times higher than non-immigrants.

Our recent research and theorising suggests that discrimination and social exclusion may lie at the heart of the immigrant psychosis problem.

We define who we are largely on the basis of the groups to which we belong. This internalisation of our group memberships is referred to as "social identity". Social groups may revolve around common interests and beliefs such as book clubs or political parties, but they may also emerge from social categories such as gender, culture, and ethnicity.

Possessing meaningful and positive social identities has been linked to a range of positive health outcomes, from slower HIV progression among HIV-positive gay men to improved general health and life satisfaction. Lacking strong social identification is also associated with higher rates of reported depression and anxiety, while interventions designed to help people join and identify with groups can help to reverse these effects.

Cultural identity and paranoid delusions

In the US and the UK, recent elections and referendums have been won on the back of demands for tougher immigration policies. Phrases such as "immigration ban", "Muslim ban" and "refugee ban" litter news headlines.

Regardless of the motives behind these policies, such messages seem particularly harmful for immigrants. Anti-immigration sentiment, for example, has been linked to feelings of isolation and depression among Mexican families living in the US.

There is compelling evidence for an association between this kind of racial discrimination and psychosis. However, our work suggests that having strong identification to a particular culture, such as African-Caribbean or Muslim, may counteract the effects of anti-immigration rhetoric and discrimination on psychotic symptoms.

Paranoid delusions – fixed, false beliefs that you are being persecuted by a person or group – are the most common symptom of psychosis. Our research has suggested that weak identification with a particular cultural group leads to the early warning signs of paranoid delusions, including low self-esteem and a reduced sense of control over one's life.

Research by one of us – Richard Bentall – using data from 208 bilingual (English and Arabic) Emirati women attending college in the United Arab Emirates, provides an empirical demonstration of the link between cultural identity and paranoia. The study's participants completed a survey that measured their level of paranoia, as well as their language proficiency and Emirati identification. People who were more paranoid tended to agree with statements such as "I believe that some people want to hurt me deliberately". People with strong Emriati identities agreed with statements like "I feel a bond with Emiratis."

They also completed a computerised task that assessed their implicit preference for both Emirati and American culture, which required them to indicate whether words were positive (for example, "fun") or negative (for example, "pain") as quickly as possible. Before each word was presented, an image associated with either Emirati or American identity briefly flashed up on the screen. For example, an image of a traditional abaya, or cloak (Emirati identity), or the Statue of Liberty (American identity). If people felt positive about Emiratis, they had faster reaction times to positive words preceded by Emirati identity images, and slower reactions times to negative words preceded by Emirati identity images.

We discovered that participants with greater Arabic language proficiency and stronger implicit preferences for Emirati culture were less paranoid. The most paranoid participants were those who indicated English was their dominant language and who displayed an implicit preference for American culture.

These findings suggest that people more connected to their original culture and practices are less likely to become paranoid. Ongoing work that we are doing within neighbourhoods in the UK is indicating a similar effect: people who identify more with their local neighbourhood report fewer paranoid beliefs.

To integrate or separate from your new culture?

So, if strong cultural identities can protect people from developing psychosis, is it best for people to maintain their original cultural identity after immigrating to a new country or to identify with their host culture – or both?

Evidence suggests that immigrants who live near people from their own culture have lower rates of psychosis. Known as the "ethnic density effect", this suggests that maintaining ties to your original culture protects against psychotic symptoms.

You could argue this indicates that distancing yourself from your host culture in favour of your original culture may be beneficial. However, if, as we argue, the risk of psychosis is increased by a person feeling isolated or discriminated against, a better strategy might be to work on increasing tolerance and welcoming immigrants into more social groups.

That said, research has indicated that being discriminated against in some cases enhances cultural identity and well-being. However, other research has shown that higher levels of discrimination are associated with more psychosis, suggesting any positive effects of discrimination are swamped by its negative effects.

When it comes to social identification, it is a case of the more groups the merrier. Possessing multiple social identities has been associated with lower depression and greater resilience in the face of challenges. This implies that identifying with both your original culture and host culture after immigration – through integration – will reap the most mental health benefits.

All this means that if we want to reduce the psychosis burden affecting immigrants, governments and citizens need to increase their efforts to make all people feel welcomed and included, and provide pathways into social groups. The combined body of evidence suggests that anti-immigration rhetoric is likely to foster feelings of isolation and discrimination, and in turn increase immigrant psychosis rates. However, if immigrants feel connected to their original and host culture, and are able to join more social groups, it is likely to counteract this problem.

This article was originally published on The Conversation. Read the original article.