Substance use and PTSD in migrants and refugees

Background

Understanding the mental health of migrants and refugees is an important public health issue as over 258 million people are currently living as migrants outside of their birth country. Of these, there are over 25 million refugees which have been forcibly displaced by persecution, war, or violence.

We have seen high rates some mental health problems in migrants, including high rates of post-traumatic stress disorder (PTSD) and psychotic disorders like schizophrenia.

Why did we do this study?

Previous research has also suggested that exposure to traumatic events might be linked to the development of substance use disorders. To explore this further, we looked at the rates of post-traumatic stress disorder (PTSD) in migrants, refugees, and Swedish-born, and looked at the association of PTSD with substance use disorders in these groups.

We also wanted to explore what happened over time to rates of mental health as migrants and refugees lived longer in the host country.

What did we do?

We used data from the Swedish population registers, which includes all individuals living in Sweden, and collect information on age, sex, migration status, education, income, and health care. We included 1.3 million people born between 1984 and 1997.

Exposures: We included people from 5 regions of origin: Sweden; Eastern Europe and Russia; Asia; Middle East and North Africa; and sub-Saharan Africa. We classified all participants by refugee/migrant status:

• refugees
• non-refugee migrants
• Swedish-born

Confounders: We adjusted for Sex, birth year, family income, family employment status, population density, and PTSD diagnosis.

Analysis: We calculated incidence rates per 100,000 person-years by migrant status. We then fitted Cox proportional hazards models for each outcome, estimating unadjusted and adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for each of our exposures.

What did we find?

Initially, both refugees and non-refugee migrants had lower risk of substance use disorders (including alcohol use, cannabis use, and poly-drug use) than the Swedish rates, however their rates converged to that of the Swedish-born population after 10 years in Sweden.

We found that rates of PTSD were higher in refugee and non-refugee migrants than the Swedish-born population, but that the association between substance use and PTSD was stronger in the Swedish-born.

What does it mean?

Our study highlights the high burden of substance use problems in the general population, particularly among those with a history of PTSD. Importantly, the convergence of the low rates of substance use disorders in migrants and refugees with the higher rates in the Swedish-born population over time represent an important public health concern.

Read more

The paper is open access, so anyone can read the full study here in PLOS Medicine: [full text] (https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002944)

Behind the research

While it is exciting every time a paper is published, as it represents years(!) of work, this paper is also a fun academic milestone for me, as this is the first paper that was lead by a MSc student who I supervised! It is extra exciting to see a student create a strong piece of research and go on to pursue her PhD at University of Bergen! Congrats Sam!